Avoiding Basement Insulation Mistakes

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Avoid Using Fiberglass Insulation In Basements

Basement Insulation Using Foam BoardBasement insulation installed incorrectly is one of the most common Contractor errors I see on a regular. Often times the results are disastrous with severe mold and mildew problems, not to mention the loss of heating bill savings that mounts up over time.

For years contractors have been treating basements much like regular living space. It’s not uncommon to see fiberglass basement insulation in direct contact with foundation walls. Typically here in the Northeast I see several methods including:

  • Plastic vapor barrier against concrete wall, fiberglass insulation inside stud wall, then drywall.
  • Fiberglass insulation inside a “bag” hanging from the rim joist down along the foundation wall.
  • Stud wall filled with fiberglass insulation an inch or two away from the concrete wall.

This may seem like an obvious problem but the fact that I see contractors still using fiberglass insulation in basements leads me to believe that the industry needs to do a better job educating our builders. In order to understand the issues with basement insulation it’s first important to understand the role of vapor barriers and vapor transmission in basements.

Basement Insulation Vapor Barriers

The trick with basement insulation jobs is in understanding where water vapor is being stored and where it’s moving to. Concrete is like a huge sponge which holds water and water vapor for years and years. As the wall dries the water vapor leaves the concrete and tries to penetrate the insulation and wall. This is where water vapor can get trapped in fiberglass and cause serious mold problems. For a more detailed discussion on vapor barriers check out this article.

Closed Cell Foam – Spray or Board Type

Over the years I’ve come to rely on two approaches for basement insulation projects and remodelling including closed cell spray foam and closed cell XPS foam board. When installed in the correct thicknesses these to methods result in a proper vapor barrier and a superior insulation.

Often times we end up insulating basement walls with a hybrid approach. First we install two inches of rigid foam board insulation (closed cell). Then we build a stud wall which holds the foam board in place but also provides room for wiring and HVAC. Depending on the level of insulation needed the stud cavity may be insulated with fiberglass or mineral wool.  To learn more about this method please read this basement insulation article.

Get Educated – Be The Pro!

Let’s face it, we live in a time when the building industry and building science is changing rapidly. In order to stand out in the competition and provide a professional service to your clients you need to stay educated on the latest methods. There are several great publications on this topic including the ones above and ones found at Building Science.

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Todd Fratzel is the editor of Tool Box Buzz and president of Front Steps Media, LLC, a web-based media company focused on the home improvement and construction industries. He’s also... Read more

142 comments on “Avoiding Basement Insulation Mistakes

  1. Mark

    Todd, I read this on your site last year and followed it to the letter. So far, so good. <50 percent humidity in the summer running a dehumidifier, and so easy to heat in the winter that my projector heats the room. Thanks for being so free with the excellent advice. Had I not talked to you, I'm sure I would have made the same mistakes.

    1. Paul

      I have a concern about insulating my basement. I have insulated my basement so far with closed cell rgid boards 1.5 “. Now do I do the floors next with the same r igid boards , plywood on top then my studded walls filled with pink insulation or do I put my studded walls after my rigid foam on the walls and then the floors with rigid foam..
      Now in either case do I leave a gap between my studded wall fiilled with pink and rigid foam wall . Is it also necessary to plastic the studded wall before putting the drywall…

    2. Alex

      I am in the process of preparing my basement for insulation . My basement has an interior perimenter drain leading to a sump pump that works well. I have already taking care of exterior issues such as grading and down spouts. My question is that the basement walls have been previously painted , should i bother trying to add a masonry water proofer prior to insulating and framing if i dont have water leaking through the block foundation? Is controlling the humidity sufficient enough?

  2. Ed

    I have been insulating basements with ridgid foam insulation for over 39 years. A new system is on the market, there are u channels between the 15 1/2 inches of foam insulation, In the u channel is a stud. You plumb all the studs in the u channels and then fix the studs in the channel. You run your electrical through the studs then screw the gyp-rock to the studs. Fiberglass does not have a true R value. I spray foam between the floor joists.

  3. William

    Thanks Todd;
    The more you educate the easier it will be to get jobs based on performance rather than price. As Mark experienced, the right approach means more comfort, safety, and long term cost reduction.

  4. Bob

    Great article I enjoyed the read I’m still getting to grips with the North American issues of severe temperature changes. I have been in Canada for almost 12 years from the UK and there are some fundamental differences.
    This is a great forum.

    Thanks Bob…

  5. Marie G

    OK so in saying to use board for basements, my new home is a 100+ year old block twin home with five stories (including basement and two attics). The long term goal is to insulate as I get renovations done or I need to open up the plaster walls. As a single mom spray would be way beyond my budget; is foam board my best option? FYI the home is balloon frame too which is one of the things I want to fix since I saw neighbor’s house go up quick in a fire.

    1. Joe Sainz

      Marie – foam board can work well in your situation. Be sure that the masonry behind is in very good shape before starting anything, because now is your only chance to work on it.

      Regarding the balloon framing – you can get every nook and cranny filled in with wood, and utilize cans of fire retardant spray foam.

  6. tom

    so i have an eight year old home and i am finishing the basement, there already is r12 and vapour barrier hanging from the top half of the walls…my question is can i keep that there and reinsulate the entire wall or should i take it down?

    1. Joe Sainz

      Tom – I’m guessing that the top half of your walls are wood framed and above grade? If that’s the case, I would leave it in place. If it’s below grade I’d remove and replace. You may need to check with Canadian code too (I’m definitely no expert there!).

  7. Jeffrey Madej

    I am lookinh to install Foam Board on my basement walls. The issue is many foundation walls have a metal clip of some sort that protrudes from the wall every couple feet. How do you normally deal with that? Can they be cut off?

    1. Joe Sainz

      Jeffery – Those sound like snap ties or flat ties. They are designed to break off just below (or flush) with the concrete. Typically they can be removed either by twisting them until they break, or pounding them side to side, or hitting them with a 2 pound sledge. You can also use a grinder if they are giving you trouble. They were used to hold the concrete forms together, and now that they walls are in place, they can be removed.

  8. Bruce Evans

    Todd, I have downloaded all your articles, thank you for the great information on how to add insulation to my Maine home basement. I am below ground, and while I would love to spray, the cost is high compared to the Pink. Any way a DIYer can spray for the between stud insulation or is that contractor work only? Also, two walls of my office add-on will face basement space (less heated) and I want to sound proof these–but Safe’n’Sound™ has no R value. Do I need 2×6 interior facing walls and use sheet rock, blue foam, sound batt, and interior sheet rock? Where would I put a vapor barrier in this instance? Thanks in advance!

    1. Todd Fratzel Post author

      Bruce – Spraying is definitely something left to the PRO’s. As far as interior walls, in most situations fiberglass is fine, I’d go with Kraft faced and put that to the cooler side. Good luck.

      1. Bruce Evans

        Todd – Thank you very much for your fast reply to my post, I appreciate it. I would like to clarify the order, and the application of the Safe n Sound batts if I may. From the basement space towards the inside of the office: sheet rock, Pink with kraft side this way, then my Safe n Sound, then my office sheet rock. Do I need to do anything in between the Pink and sound batts? SnS is meant to cavity “stick” through friction as it has no facing on it. My thought was was 2×6 stud wall to accommodate the two. The office will be used for voice over recording, and so needs the extra sound proofing. Sorry for the extra questions, but you are my final word in terms of materials and approach–so far you are the only one who consistently makes sense! Thanks again, BKE

        1. Todd Fratzel Post author

          When it comes to sound proofing, I’d recommend a bit different approach. Instead of framing with 2×6’s, I would use either 2×6 or 2×8 top and bottom plates. Then use 2×4 studs. Frame the studs flush to the basement side at either 16″ o.c. for 1/2″ rock or 24″ o.c. for 5/8″ rock. Install the fiberglass on that side.

          Then on the office side, frame another 2×4 wall, again 16″ or 24″. Except stagger the layout so these studs fall in the middle of the other side stud bays. Then install your noise insulation on this side and drywall.

          This will create a much better system. Noise is transmitted through vibration, this eliminates the studs from each side from transmitting vibration to the other side. Good luck.

  9. Ryan

    This is a great article – thanks for sharing. I was curious how you would apply your knowledge to a damp basement situation? Due to moisture penetration issues through our basement cement block wall foundation, an interior French drain was installed, which has worked perfectly. We installed a 9mm thick plastic vapor barrier up against the wall so any water that comes in the foundation above the weep holes will not touch the studs or insulation, and will be diverted into the French drain. This has also worked quite well, however in the winter months we are getting condensation on the outside of the vapor barrier, which in turn is making the fiberglass insulation wet. From what we have read, closed-cell spray foam seems to be the answer for insulating in an environment that may experience dampness; however we are curious if we should spray the foam on top of the vapor barrier, or take down the vapor barrier and spray the foam up against the wall? Our concern is that the insulation will be getting damp whether it is applied to the wall or the vapor barrier, and want to ensure the moisture continues to be diverted into the French drain. What setup of insulation might you recommend in this situation?

    1. Todd Fratzel Post author

      Ryan – Seems like you can spray on top of it. However, first you’ll need to make sure the insulation won’t cause a negative effect on the vapor barrier. Water will not hurt closed cell foam.

  10. John O'Connor

    I have a 20 year-old home with an unfinished basement that I want to tidy up with insulation to help heat the floor above. My plan is to spray foam (myself) along the foundation and then put pink insulation under the 1st floor (in between studs in basement ceiling). I’m a novice — is this approach reasonable and if so, what’s the right insulation to buy? House is in Maine Thanks!

    1. Todd Fratzel Post author

      The spray foam should be a closed cell foam and you’ll need 1-1/2 to 2″ in order to create a proper vapor barrier. As for the floor, you can use any type of fiberglass, be sure the vapor barrier goes up against the floor (warm side) then use wire insulation supports to keep it all in place.

  11. Jeremy David

    I have an 8 year semi detached home in toronto Canada. From the floor joist halfway down the poured concrete basement wall there is fibreglass insulation with vapour barrier. All this is above grade. Can I keep it? Thank you.

    1. Todd Fratzel Post author

      Jeremy – I see this detail quite a bit and frankly I don’t like it. I guess the question is whether you plan on leaving the space unfinished or not. If you plan on finishing it I’d remove the fiberglass and get some foam in place first. You might be able to save that and use it for supplemental insulation after foam. Good luck.

  12. Rich


    I am wanting to finish my basement. I have read your article and think that is certainly the way to go. I have a 105 year old home which has a stone foundation which has had 3 course of block added on top of that years ago to raise the house. Since the walls are uneven due to the stone foundation, what would you recommend to do in place of the foam before insulating and hanging drywall?

    1. Todd Fratzel Post author

      Rich – The best approach for stone foundations is having closed cell spray foam applied. Obviously that comes at a price but it’s an investment that I think is worthwhile. Having said that, stone foundations are notorious for leaks and unless you live in an area with a very dry sub-grade I’d be cautious and really make sure you want to invest in finished space.

      If spray foam is out of the question, then if it were my place, I would likely frame walls and install foam to the back of them before tipping them up. The trick if finding a way to seal the corners and other joints after. Good luck.

  13. Matt


    I’ve installed the rigid foam on the walls as well as the top of the foundation against the sill plate. I have used spray foam on the bottom of the rim joist cavities, and used silicone caulk on the top. I taped off all of the seams on the rigid foam. My question now is should I seal the rigid foam board seam against the floor? My plan is to leave a 1″ gap between the rigid foam and my stud wall, then insulate my stud wall cavity with unfaced batts, no vapor barrier. I haven’t decided on a floor method yet, but i’d like to have some type of subfloor so my flooring isn’t directly sitting on the cold concrete.


    1. Todd Fratzel Post author

      Matt – Good question and unfortunately I’m not sure there’s a “right” answer. Ideally you’d seal it up, but the ability to do that with much success can be hard. If your foam has a tight fit then I’d just leave it at that. If you’ve got noticeable gaps then I’d recommend sealing those.

  14. Rick


    Like others here I own a house that was built 100+ years ago and has a concrete block foundation. I was wondering if there is a need to seal the block walls prior to installing the rigid foam insulation? This is done quite often from what I have seen in homes in Michigan. I know during very heavy rains there are points in the walls where I have moisture problems. I have taken and will be taking care of the rest of the external factors that cause this, but I still have concerns.

    Thank you

    1. Todd Fratzel Post author

      Rick – Many people do, I find it to be a “belt & suspenders” approach. If you have the time and money it can’t hurt. I frankly don’t have much faith in those sort of products as it’s like putting a finger in the dam.

  15. Maryann McCandless

    I have a basement built in 1967. Northeast coastal location. The home is new to me. The basement was finishe when I purchased. Sheet rock has been removed. Water problems have been repaired. Insulation was removed from ceiling.

    I now have a dry basement with studded walls with fiberglass batts with paper side out. Maybe 3 or 4 studs have mold.

    Now what. Want to sheet rock. Called contractor. Said fiberglass in rim sill will be comparable to rigid foam cut to fit. Will bid spray foam for. walls and rim joist. I am concerned about long term outgas and cost. He said fiberglass looked good and he could replace the ones that needed to be replaced.

    What is best and most cost effective before sheet rock goes up?

    1. Todd Fratzel Post author


      If the studs are tight to the concrete then it really should be spray foam. I do not recommend Fiberglas for the walls and I’m not a fan for the rim joist area either.

      Foam board or spray foam is what I’d recommend in the rim joist.

      Good luck.

  16. Danielle

    I have a stairway in which the bottom part of the stairway is next to the exterior wall of the house. I know the proper way to drywall over the foundation is to first apply the foam insulation, then build the wall, leave 2 inches before drywall for airflow; however, there is NO room for insulation or even 2x4s to protrude into this area of the stairway (in is already grandfathered in and less than 36 inches wide- the house was built in 1906). what options do I have? can i put shims against the cement and then put drywall over them? I live in desert climate with little rain, we do get some rain and snow but low humidity allows things to dry out quickly. what can I do?

    1. Todd Fratzel Post author

      Without room to insulate I’d probably recommend either just painting the wall or having a texture applied to ‘dress’ it up. Short of moving the stairs you have very few options.

      Good luck.

  17. Michele

    Thanks for this article; it’s helped me narrow down my options significantly. May I ask your advice for my specific situation?

    My basement is mostly concrete (slab and walls), but the upper half of the southeast wall (and the upper half of parts of the adjoining walls) are above grade and consist of studs against … fiberboard? (Construction was in 2000.) The previous owners had fiberglass batts in this space, as well as between the floor joists (basement ceiling). The batts in the walls were either unfaced or faced towards the wall, not the unheated-but-moist room. There was no other vapor barrier for the walls. (The ceiling batts are properly faced towards the warmer upstairs living space.)

    One of my cats was *eating* this stuff, so I had it removed from the walls, and I learned that it had encouraged mold growth along the walls behind the insulation.

    So those walls are now uninsulated, and the basement is freezing. Should I leave them as they are? Use spray foam in those spaces? Wait until I can afford to insulate the concrete walls as well?

    And should I replace the “ceiling” batts with something else (spray?)? If not, is there a fairly cheap barrier I can install to keep the cat away from that portion? (She’s a little too clever at being foolish.)

    Many thanks for any advice!

    1. Todd Fratzel Post author


      For the wood framed portion you can clean the old mold, then insulate the stud bays with foam, fiberglass or cellulose. The key is to install a proper vapor barrier after it’s installed. The ceiling should be fine as is.

    2. Michele

      Sorry, left out two minor details: I’m in New England; and my goal isn’t to make the space livable, it’s to avoid worsening my heating requirements upstairs (or the performance of my water heater).

  18. Thomas

    I live on Northern Border of PA. Trying to finish basement of 7 year old addition w/ wood burner in adjacent basement.
    I offset my wall panel 1″ from Drylocked foundation wall. Before I could drywall the fiberglass kraft side I found moisture on unfaced side.
    I can remove the panels,PT toe board and replace at 1 1/2″ for foam board.
    My concern is – due to exterior insulation board up to ground level, about 50% wall on a slope, will this cause more problems?

    1. Todd Fratzel Post author

      Thomas – Not sure I 100% understand your situation. Let me give you my thoughts on what I’d do.

      Regardless of whether or not there’s any exterior insulation, I’d recommend installing at a very minimum 1-1/2″ XPS foam board (2″ is much better). Then your framing and any additional insulation (fiberglass, cellulose, foam). If you use a kraft faced fiberglass I’d recommend cutting some holes in the paper to let it breath. Finally the drywall. Good luck.

  19. Rudy Showalter

    Hi Todd,

    I have a home 10 years of age. Live in Missouri and the basement is dry. Studs are already installed around the parimeter of the basement. What do you recommend for insulation since the walls are up? Foam spray, Reflectix rolled in between the studs or 2 inch foam board between the studs?

    Thank You Sir!

    1. Todd Fratzel Post author

      How close are the studs to the concrete? If they are tight against the concrete I really can’t recommend much as anything you do will likely end up with a moisture/mold problem down the road. If there’s a small space (1″ min) then you can use spray foam (closed cell only) and seal it pretty well. Short of that I’d recommend you slide the walls forward and get at least 1-1/2″ of closed cell back there.

  20. Rich

    I have a new house with an unfinished lower level. It is a split so half of the walls are concrete foundation below grade. The exterior of the foundation was insulated with closed cell insulation board. Above grade are stud walls with fiberglass insulation. The lower level still seems very cold. Can I insulate the interior concrete wall? Ive heard that if the exterior foundation is insulated then you shouldn’t insulate the interior part of the foundation otherwise the moisture from the concrete has no where to go. I do have proper grading and gutters with diverters. Minnesota cold climate. Please help!!.

    1. Todd Fratzel Post author

      Rich – You certainly can insulate the interior with foam insulation. Not really any different than ICF foundations where the core is concrete and the exterior and interior are foam. Concrete doesn’t need to lose it’s moisture, in fact, it is more than happy being in a wet climate. I have lots more info on this topic here: http://www.homeconstructionimprovement.com/how-to-insulate-basement-walls/

      That article also includes links to other pertinent discussions. Good luck.

  21. Jim G.

    I have a basement that has just been repaired a year ago with steel I beams( 5 and 1/2″ out from wall)running along all 4 walls(roughly spaced between 26″ and 30″ for slightly bowed walls. Fixed bad gutters and grading, have sump pump and basement dry for year. Concrete block walls. Basement(rectangle shape 22’x40′) is split the long way by studded wall ,finished(had to teardown walls for support beams)/unfinished. Small house, want to maximize space, any ideas on how to put up walls/insulation? Stud inbetween beams(almost impossible to get 16″ on center studs for drywall) or put up wall in front of beams(and lose roughly 9 and 1/2″” of living space) and was going to put up fiberglass insulation until I read your post(thank you). On the unfinished basement walls would it pay to put up foam inbetween beams and then..??? paint them? Can u paint them? Money’s somewhat tight. Really want answer on finished side, was going to leave unfinshed side bear.

    1. Todd Fratzel Post author

      Jim – Without seeing a picture it’s pretty hard to say what the best approach is. Definitely no fiberglass with the exception of an interior separation wall. Most likely, the best approach is framing in front of the steel.

      1. Jim G

        I was afraid you were going to say in front of steel beams better, seems alot easier then to hang drywall, but losing roughly 60sq ft of a small basement area. If I use use the pink R10 2″ insulation sheets is that OK on concrete ‘block’ walls(will be put up in 26″to30″ X 7′ strips, and will just glue support it? Some videos online I seen had the builders put up the styrofoam sheets the brace there stud boards right up against it to hold it up, I wouldnt be able to do this because being in front of steel beams I would need 9″stud boards. Is was just tuckpointed last year, should I paint it with waterproofing paint 1st?

    2. Stephen

      Did you ever solve this or come up with a solution? I’ve got an exterior wall with steel i-beam reinforcement, and am starting the planning for refinishing it back to usable space.
      My thinking had been to put up 2×4 studs with top and bottom plates between the steel beams, flush with the face of the beams, so there’s still a gap between the studs and the concrete of course. Then, insulating using closed-cell spray foam in the gaps, encasing the studs and beams. My only concern was the thermal bridging between concrete and steel, as there’d be no break between these materials and the drywall. I imagine this would result in – at best – cold spots on the wall, and at worst condensation problems from the warm interior air hitting the colder steel. My basement wall has rigid foam on the exterior, so it’s not completely bridged to the outside soil, but I think my worry would be condensate forming on the steel interior face. In theory it could dry to the inside since there’s only permeable drywall atop it.
      What did you end up doing? Any thoughts on my approach described above?

    1. Todd Fratzel Post author

      Steve – I’ve never used this product. However, looking at their website I can’t see how this product can solve the issues involved with moisture and thermal insulating. Even if you install a layer of this stuff against the concrete prior to framing, it won’t insulate the concrete surface enough. This product will also be cold, any moisture that gets into the stud cavity will condense against it. I just can’t in good conscience recommend something like this. The old saying still stands true…..”You get what you pay for”. Good luck.

  22. JG

    Great Site, Thanks! I am replacing a shower in a sub-grade basement. I have taken out the old stand alone shower stall and have cleaned down to bare studs. One wall is a poured concrete wall. There were 1 x 3 strips nailed to the concrete and then sheet rock. What should be on my inside studded walls (water-board? what ratings?) How should I treat the concrete wall? I am concerned about moisture from the concrete wall and moisture from the shower side enclosure? Thanks in advance. Keep up the good work. JG

    1. Todd Fratzel Post author

      JG – Are you putting in a stand alone shower or tiling? For the concrete wall, you really need to get at least 1-1/2″ of closed cell foam (continuous). Whether you frame a wall, or use strapping (furring), the key is the foam, properly sealed. The interior wall, that really depends on the type of shower.

  23. Marc

    Todd – I have find the website to be extremely informative. I want to ask your opinion on our basement in Michigan. We have the Superior Wall R5 system, http://www.superiorwalls.com/pages/products/r-5-wall, and I am looking at finishing the walls. The walls have R5 already and the humidity(+70%) can be an issue in Summer. We do use a dehumidifier. I have read by your accounts and others not to use Fiber. My thought is to place another 1″ R5 layer of foam board over the existing R5 foamboard. I have read to “foam in” the edges to the concrete studs. Is that necessary?
    I was not going to add a vapor barrier or anything else. I would then drywall over the wall studs build into the wall. Do you think this is sufficient enough or do I need to go thicker? I have read some others add foam and them un-faced fiber over the foam to bring a higher r value. Lastly, is this the best way to go about it. Thank you!

    1. Todd Fratzel Post author

      Marc – I haven’t been involved with a Superior Wall project so my opinion isn’t backed by any experience with this product. In my opinion you’d want to get up to about R20 as a minimum. Having said that, it seems that foam would be the best approach. The concrete studs have moisture in them, and will for their entire life, so I’d avoid any fiberglass. Yes you can attach the drywall to the stud per the Superior Wall spec’s. Good luck.

  24. alan

    Nice forum. I want to get your suggestion on my specifics before I finish my walkout basement (in KY). There are poured foundation walls below grade and studded walls with unfaced batt insulation above grade. First, what do i do with the concrete walls… poly vapor barrier then frame and unfaced batt -or- xps foamboard then frame (and maybe more unfaced batt)? Second, for the above grade… do i leave as is or do i need to put poly over it? Third, what is best way to sound-proof between basement and level above? Finally, do you have any suggestions on radon systems? should i take it out through roof or out side of house?

    Thanks in advance!

  25. Dan

    I have a new house in WI. The basement insulation system the contractor installed is 2×4 studs with fiberglass batts in between. Most of the studs are 3/4″ away from the concrete, some more some almost touching the concrete. I’m trying to avoid tearing down all the stud walls. Can I cut 1.5″ closed cell foam to fit between studs (replacing fiberglass) and spray foam the seams behind the studs? I’m afraid that may not be enough insulation directly behind the stud, but it would save a lot of work tearing down the walls to put up full sheets of rigid foam. Thanks

    1. Todd Fratzel Post author

      Dan – If it were my home, or one of my clients, I’d slide the wall forward and install a proper layer of insulation. Moving the wall isn’t all that difficult unless there are lots of utilities already installed in the wall. You don’t need to remove each stud, typically you can cut the top and bottom plates “free” of the floor and ceiling framing, tip the wall down, install the insulation, and tip the wall back up.

  26. Ken

    For a basement in Canada ( 10% above grade, 80% below).
    Concrete walls
    1″ Foam
    space or no space ??
    Studs 2×4
    Fiberglass batts between the studs
    Poly ** or no poly. .???

    1. Todd Fratzel Post author

      Ken – At the very least you need 1-1/2″ minimum of foam, being in Canada you’ll likely need at least 2″, more if you can afford it. Be sure all the seams are taped and sealed. Space is optional. NO poly over the fiberglass.

      Good luck.

  27. jason

    So I have a 20o year old cabin in the Adirondacks. The stone foundation leaks horribly and has for many years before me. It comes in and goes out via sump pump. Problem is horrible smells of mold and poor air even sitting on first floor.
    Can I put closed cell boards in floor joist bays and seal w spray at edges to create a barrier from basement air to the rest of house? Maybe spray w paint sprayer all first then enclose w boards then paint all basement again to seal since scrubbing has only done so much

    1. Todd Fratzel Post author

      Jason – Honestly, the first thing I recommend is finding a way to control water. There’s simply practical way of sealing your basement from that amount of moisture.

      1. jason

        Due to grades the only practical way requires an excavator and probably few hundred feet of perforated pipe, clean stone for the trench etc. For my timeline prior to my wife giving birth I must clean the air on the first floor. In time I do plan on dealing w moisture properly for future air issues. But the damage is already done down there and I need to seal us apart before I can clean that air properly.
        So would that create a Barrier fro. The bad air, at least some, and not be a complete waste of money. I can do that by myself in a weekend w/o having to load our excavator and bobcat at work and deliver over an hour to my house w materials also. Frankly I’d be paying someone else’s wages vedpre we even had equipment digging here. But vapir barrier well, I am free.

        1. Todd Fratzel Post author

          Jason – I’ve never dealt with this situation so I’m purely speculating. I guess one approach would be to try and paint all of it with BIN primer. Then install the foam from below and seal it. In many locations, exposed foam is a fire hazard and not allowed by code, so you’d need to consider that as well. It seems some better ventilation down there might help as well. Good luck.

  28. Tamer

    My basement is already framed, should I try to use the 2 inch pink insulation if I can get it in? or should I just use the fiberglass?
    I have one room dedicated for a wine cellar, my plan was to skip any type of insulation and just drywall it. Is that a good idea?

    1. Todd Fratzel Post author

      I would not recommend fiberglass unless you are able to get 1-1/2 to 2″ of foam behind the studs. If it were my house, I’d slide those walls forward and install the foam. I would NOT skip the insulation in the wine cellar.

  29. Natasha

    Hi Todd, I now have stud up, about an inch and two quarters off the wall.just came across this type of insulation. How can I add this w/o moving my walls? Electrical rough and plumbing have been done. I have a walk out basement also. If I do decide to go with this, do I use rigid foam on all concrete walls( below grade)and exterior (walkout)? Plus I notice behind the tub, it looks like my contractor just stuffed fiberglass back there. Should there be something bwtn studs and tub in shower? Thanks

  30. Joe

    I am finishing a basement in southern ontario, Canada.

    I am wondering the correct method of insulating a building a basement wall. If you could outline what exact material I should be using, that would be great! Thanks in advance. Currently, there is insulation with Poly 6 coming halfway down the wall from the top, leaving the bottom half as bare concrete. Should this be removed first? There are just small windows in the basement.

  31. Dan Haugan

    I purchased an older home and the previous owner farmed and insulated the walls (with fiber glass of course). The problem is he put vapour barrier on both sides of the insulation. My question is: will it be fine if I leave it that way or should I gut the whole basement and do it right. Because of the time, expense, the furniture and alliances that need to be moved I am leaning towards leaving it. What r my options and will it make the basement warmer if I change it. Thanks

    1. Todd Fratzel Post author

      Dan – I wouldn’t keep it that way in my home (that’s how I like to put things in perspective). You have a classic double vapor barrier and it has fiberglass in a basement, both No-No’s in my book. Foam would be the approach to use, and the warmth depends on the final effective R value. Good luck.

  32. gerald ring

    I have a tri level home I built it in 1976 recently I decided to replace wall covering in the family room I have furring strips every 16 inches the upper part 2x6s I have 6 inch bats there fiberglass the pink side is facing out vapor barrier in the bottom half I used 1 inch strofoam over the fiberglass and behind the foam I had some termite damage this has all been repaired my question is the fiberglass looks fine to me but does age 1976 come into play I have removed foam an replacing it should I replace fiber glass also? there is no visible moisture from what I can see

    1. Todd Fratzel Post author

      Gerald – Not sure of the details so it’s hard to say. Are you saying you have a wall that the lower half is concrete with furing strips? If so, I really don’t like any fiberglass in contact with the concrete. If it were my home, I’d install foam over the concrete, then possibly fiberglass over that if you can get enough foam to properly seal it. Old fiberglass can work if it’s dry and hasn’t been completely compressed. Good luck..

  33. jeff stengel

    Good summary! When I did my basement I was going to use the foam board but decided to go with framing the walls out of 2×4 steel, about 1″ from the concrete. I then used closed cell spray foam (dual propane sized cans) and sprayed the stud cavities and got behind the studs as well forming a impervious seat from the basement wall to each stud cavity. I then used R19 fiberglass insulation and filled the stud cavities and any other crevasses. Finished with mold/mildew resistant 1/2″ rock. Still smells like a basement probably because the boiler room is not finished on the exterior walls. I know it is well insulated because the lights increase the room temp 5-7 degrees.

  34. shirley

    dear todd– living in central n.y. our winters are brutal. living in a 310sq. ft. house,very open concept radient heat in basement and 1st floor, baseboard heat in 2nd floor. no wall insulation in basement [ouch]. at present researching basement insulation technichs your site appeared the most comprehensive, but was also looking at prodex total— your thoughts on this? much appreciated some thing has to be done before next cold season. thanks.

  35. Sam

    I just bought a new construction home and want to finish the basement soon. I live in a a desert state (Utah), but am always concerned about mold (though the lack of humidity in the air usually, but not always, reduces the chance of mold.). The builder put batt fiberglass insulation and used thick plastic to keep it held against all the below grade walls (diaper style). Obviously, removing all of that will take quite the dumpster and a large amount of money to replace with XPS. First question: is it worth the switch to XPS? Second question: do I put a pressure treated board against the concrete and have the XPS sit on top of that, or does the XPS go all the way from the ceiling joist to the bare concrete floor? Third question: on the building science article, it mentions that XPS is highly flammable, and that gypsum board should be placed for fire protection. My question is, do I need the gypsum, or will Sheetrock do the same job? Will it be just as fire retardant if I attach the drywall to the 2×4 frames that I will build against the XPS, or is the gypsum supposed to go against the XPS and then the 2×4 and then the Sheetrock? Last question: I have several sewer drains that are right up against the concrete (no way to put the XPS behind them) what do I do in that situation?
    Thanks for all the help in advance!!!

    1. Todd Fratzel Post author

      Sam – I’m not familiar with your climate area so it’s hard to say if I’d remove the fiberglass there but my opinion is it should go.

      The foam should go from the slab up to the top of the concrete.

      Foam insulation should be protected from fire. Drywall and gypsum board are the same thing. Building codes vary from region to region so you need to check yours on how much of a thermal barrier is required. Here in NH we need a minimum of 1/2″ gypsum board (30 minute rating) to protect it.

      The gypsum / drywall works regardless of the framing layout.

      Usually we frame around existing utilities.

      Good luck.

  36. Geoff

    Hi Todd,

    Great site and great discussion. Thanks for taking the time to help people. I’m wondering what type of insulation to use around a wood stove that sits in the corner of our basement?

    Some context… Our house is in southern Ontario, and at present it has pink bats inside the basement walls with a black matting separating them from the concrete block foundation. Unsurprisingly it’s gone moldy so we’re going to rip it all out, move the studs to create a 2” gap and add a layer of spray foam insulation to seal the walls.

    I’m expecting to need to move the wood stove a bit to maintain the manufacturers clearances because the walls will be thicker after this, but what sort of insulation should I be using around the wood stove?

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  38. Josh

    Todd –

    I’m getting started on my basement insulation and need some help. Most of the basement sits 4′ outside the ground due to my yard sloping downward towards the back yard. The original builder installed 3/4 foam board to the walls (floor to ceiling) and taped all seams. It’s an R-Matte Plus 3 from Home Depot (R-Matte Plus 3 – 3/4 in. R-5 Polyiso Rigid Foam Insulation Board). I was going to install another 1″ Owens Corning FOAMULAR 150 Tongue and Groove R5 Insulation Board against it…providing a total of 1.75″ for an R value of 10. After that, I was going to install my stud wall right against the Owens Corning board with no batt insulation. I’m also planning to have all of the rafter joists and sill plate spray foamed.

    I’ve read you do not like Polyiso. Is the r-matte on my walls the same thing? Would you recommend taking it all down?
    What do you think about installing the owens corning board up against the Polyiso boards? Will that work and provide enough vapor/moisture barrier?
    Do I need to add batt insulation in addition to the 1.75″ foam boards?

    Thanks in advance!


  39. Tom

    Todd, the information you’re providing in your original article and the advice you’re generously providing in the comments is invaluable – thank you!

    my own personal situation/question I’m hoping to hear from you on:

    We recently had a flood across our entire basement floor(approx 2 inches high). Contractors we have met with have recommended and since started removing the the bottom 2 ft of drywall and batt insulation and the plan is to replace the same new materials (except with mould resistant gysupm). My original set-up is as follows: concrete exterior walls, then ‘house-wrap’, then batt insulation between studs, then vapour barrier and gypsum board.
    Since reading most of the content here, I’m thinking that using batt insulation and the same set-up going forward is going to lead to more moisture problems. Since we only planned to replace the bottom 2′ of dryall and insulation (and they’ve already been removed), is it possible to simply install foam board or spray foam on the same bottom 2′, or is that just cancelled out by continuing to have the batt insulation / vapour barrier combo in the upper 6 feet of the wall?

  40. Tom

    Todd, in reading more of the articles you linked to above I think it’s answered my recent question, that it’s not going to be possible to use the foam board unless I also remove the existing framing – is that right? Is the spray foam still possible?
    Ultimately I’m wondering what the most practical/economical recommendation would be to reduce the moisture and risk of mold without completely demolishing the walls of my already finished basement.
    For reference, my basement is currently finished with concrete exterior walls, then charcoal colored ‘wrap/material’ (there seems to be an inch or two between this wrap and the exterior walls), then stud framing with R12 batt insulation between the studs, then a vapor barrier and finally drywall on top of the vapor barrier.
    We’ve already removed two feet of drywall at the base and I notice that the batt insulation is quite wet in some areas, but only at the very bottom (i.e. the insulation touching the base of the wood framing, which is also moist). The insulation that’s 3 inches or more away from the bottom ‘seems’ to be dry.
    Any thoughts would be greatly appreciated.

  41. Alan Ochieng

    Thank you Sir, for really educating me on insulation matters. I had the misfortune of discovering a leak in my basement and it turned out that the main water shut off valve sprung a leak and soaked the drywall and insulation underneath.Further investigation revealed that there is plenty of poly moisture barrier. And yes, the basement is below grade. Not only is there poly against the block wall, there was also plastic sheeting between insulation and drywall.
    I want to follow your advice and use rigid insulation. Is the SUPER TUFF-R 1/2 4ftX8ft R3.3 acceptable, or should I get a different R value? What do you suggest for insulating around the copper water pipe?

  42. Brandon

    I’ve seen a lot of different information on insulating basements, but your article seems the most complete. I noticed you would never recommend poly in a basement, but I was what you would do in my situation.
    My basement is below grade and contains a 45 foot long french drain against the wall with no poly to force the water to run into the drain. Could I use rigid foam insulation from the sill plate to the trench and expect the water would still make it to the drain and not adversely affect the xps if it is sitting in standing water or should I place poly from the inside side of the trench up the wall a couple of feet to isolate the drain and then place rigid foam on top of the poly?
    I’m concerned that the xps can’t be completely taped at the bottom of the wall and that without poly to catch it, the moisture would move up from the gravel to the 2×4 frame and its enclosed, unfaced BAT insulation which essentially makes all the work I did with the xps useless.
    If you could help I would appreciate it, I’d hate to spend a lot of time and money on a solution that creates another mold problem.

  43. Brad

    When my home was built, the basement concrete exterior walls had 1 inch rigid foamular board attached. All the seams were taped and/or foamed shut. The 2×4 walls were framed in front of the foam with a 1 inch air gap. All electrical, low voltage, and central vac items have already been ran in the walls. Will the 1 inch be enough vapor barrier to just add more batts of insulation, or should I spray foam on top of the rigid foam board? I am located in Northern Indiana.

  44. Marta

    I bought a 1949 900 sq. ft house in the woods. The house is 1 story, cinder block, tar-pebble roof. Half of the house is half into the ground. I guess due to the 16 degree incline on the land.

    The entire house is covered with cheap wood paneling. It is held by 2×2 studs filled with fiberglass insulation directly on the cinder blocks.

    The most in the ground corner (upper right if you were looking at a rectangle) is also where the bedroom is.

    I am doing the work, but I am not super strong.

    It is winter (Jan 2015) the house is the northern Virginia.

    I am neatly removing the paneling and insulation, bearing the cinder-block walls.

    I have read a lot and cannot come to a decision as to what to do exactly to insulate and cover the walls (if possible with something other than drywall because it is heavy).

    I have a great chance to start new and do it correctly. Have well insulated and dry walls. The project at this point is a blank canvas.

    I thought about painting with sealer first. The installing Canadian style panels to insulate and then covering with drywall IF I cannot find something that will be better and easier to work with and that will contribute to the R value for insulation.

    What do you recommend?

    Thank you for your forum and for sharing your knowledge. It is relief to be able to read it and learn.

  45. Don Lee

    I insulated a basement exactly as you described (before reading this by the way) and had a building inspector tell me that i was not allowed to use vapor barrier below grade. I’m pretty frustrated that he doesn’t understand basic building construction nor protecting the homeowner from dangerous mold.

  46. Adam

    Fantastic article.
    Todd, I’m looking to replace the batt insulation we have in our basement with rigid foam however upon the removal of drywall realised we have a carpenter ant problem. We have had the location sprayed and nest destroyed but I remain somewhat worried about using the foam option given the expence and the chance for a repeat infestation (the whole neighbourhood shares this issue). I’ve waterproofed the exterior walls this summer with tar and membrane, do you think batt insulation with a warm side vapour barrier would be sufficient? I live in southern Ontario so humidity and varying temperature is the norm.

  47. Brenda

    Todd – I built a cement patio outside of two cellar windows. They were never sealed. I notice mold between the glass and outside. There isn’t any mold on the windows inside the cellar. I caulked the windows so there isn’t any airflow coming into the basement. What is the best way to seal the windows?

  48. Mike Thompson

    Been reading the comments and believe you can provide an honest solution/comment.
    House is 40-45 yrs old wooden type. No basement, however lower level is split. Botttom 4 feet is cender block, upper is basic 2×4 studs. The junction between the two is a 2×8 or 2×10 wooden plate.
    Location is upstate NY North of Albany. Moved here 4 yrs ago and have found the winters rather cold. Looking to insulate at least the lower level. Can’t seem to find any kind of agreement from the locals on how to go about it. I would like a soultion I can do myself.
    Your comments will be very welcome.
    Mike T

  49. Gary

    Hi Todd.
    Recently gutted and re-framed 75% of my basement, here in Michigan.
    A friend recommended that I use double-sided foil type insulation. Which I did with the walls being 3/4″ to 2″ away from outer wall.
    Now that most of the Drywall is up…I’m second guessing if this is correct?
    Should I have installed additional insulation in between the 2×4’s? If so, what kind and can I do something without tearing the drywall out?

  50. mike

    open or closed cell spray for rim joist and sill? there is foam board on the outside of the house. I’m concerned if I use closed cell, the sill and rim wood won’t be able to breathe and rot. the sill lies directly on the concrete foundation. I am leaving towards open cell for this project. do u agree?

  51. Brian

    I just moved into a house with half the basement finished, they put 2×2 sleepers on the cement floor then plywood . There is no foam on the floor. Just wondering if this is good enough or what my options are to fix it? The basement smells a little damp, I’m sure the walls are not done properly either , but I can take down the drywall and spray foam the walls I just hate to tear everything down and send it to the dump

  52. Anna

    Please help! First time finishing a basement. We have it framed in. New electrical installed and updated. Now comes insulation before hanging drywall. What should we use? After reading this article it sounds as if we should have installed insulation before framing. Any suggestions for what to do since it is already framed? We did use Drylock on the walls before framing…


  53. Mike

    Hi , half my basement is finished with fiberglass with paper backing. It is framed with 2×4 attached top and bottom with treated wood on bottom with sheet rock.
    I want to finish my shop side in the same manner but now question the use of fiberglass ? Should I go with foam board? And thickness?
    I also want to remove batt insulation in the ceiling. What is the safest way? And should I leave insulation out or use foam in ceiling also. I see most people concentrate on walls.
    I would greatly appreciate any help with this . Feeling overwhelmed .
    Thanks again
    P.s humidity in basement at about 55%

  54. TJ

    Hi, I moved into a house that was closed up for 4 years. I lived there previously and knew the basement was humid. Small patches of mold grew because of this. I had the basement stripped before I moved in but I did not see what type the insulation was. It’s framed out from the block wall 6″. Can I use fiberglass or should I use foam board? And what R rating is best?

  55. Lawrence

    Hi everyone,

    Thank you for all the helpful information on insulating a basement. I am about to move into a house where I had the fiber glass insulation removed (based on the sound science advice given by Todd). Therefore, I am looking for a contractor or someone with experience in insulating basement walls with foam boards (more affordable than foam). Can anyone recommend a contractor or someone in the Columbus, Ohio area with experience using foam boards so that I can finish my basement. All the contractors I have spoken to seem to prefer fiberglass insulation because they think it is cheaper and can fit into more corners. Thank you for your help.


  56. Howard

    Spray Foam insulation is something that I’ve been coming across more and more often. Living in a developing neighborhood, I see many unfinished basements. This allows me to see what people are using behind the eventual drywall panels and hardwood floors. I have seen that there’s a lot of spray foam that’s being applied, which from what I’ve heard about it, should make a huge difference to the overall atmosphere in the setting.

  57. Brian W

    My house is 18 years old with a poured concrete basement. The contractor used fiberglass insulation with a plastic barrier on the interior side. It’s held in place by metal fasteners that are driven into the concrete. The fiberglass is in direct contact with the concrete. If I want to finish my basement into a living space should I remove the insulation and put up foam board in its place?

  58. Rickey

    So I’ve already framed out my basement using metal studs. I’m going to be moving forward shortly with electrical, spray painting the ceiling, and then onto the walls. The walls were framed about 2.5″ from the cements walls. I’ve read a lot that air movement is recommended for making sure to not have any mold, that’s why the walls are where they are. In regards to insulating, since I’ve got the air movement, I was expecting that fiberglass insulation between the studs would be sufficient. If it’s 100% not, then would I still be ok with gluing the foam board to the cement walls behind my studs and putting in the pink in between the studs?

  59. Rose

    Just moved into a 10year old mattamy home in Milton ont. we seem to be having an issue with what we believe to be condensation just on a few walls where the cold cellar should have been. Right now there’s the pink insulation halfway down the wall covered by the vapour barrier plastic. The water is only on the bottom part was this insulated correctly and how can I fix this issue? We are currently running a dehumidifier any help would be greatly appreciated:)

  60. Matt PSU

    2 years ago I bought a home with an existing finished basement. The basement also has a 100sqft storage room with the HVAC equipment, plus about 200sqft of 3′ crawl space that is non-insulated. The exterior walls of the finished portion have the plastic barrier and fiberglass behind drywall. However the contractor chose not to insulate the interior walls facing the storage room. Also the door to the storage room is an interior door that is not sealed well. Therefore the storage room and crawlspace are kept at room temp, which is obviously costing $$$. There is no sign of moisture problems (yet). What is the proper way to insulate the interior walls? Plastic sheet and roxul? Also could I be creating more problems than just keeping things as they are?

  61. Greg

    Hello Todd, I have a home that is a rancher and Im working on the basement walls now. It has a block walls, now I bought XPR owens and I have it coming tomorrow. Do I put that straight onto my walls and then stud over top of it? My house was built in 1952 and its solid, but it did have some slight moisture issues, but I dug out front and used hydraulic cement and everything seems good. Any ideas or am I good at what I might start this weekend. Thanks in advance

  62. John


    The basement laundry room walls are insulated above grade with 1 inch white foam board. The joints are not sealed and the foam is exposed. Below grade is the bare cement block wall.

    I want to use the XPS foam boards 2 inch and fibreglass, the question is whether to remove the white foam boards….

  63. Robert Reddington

    The basement in my home was constructed with pre-cast concrete panels, they are top notch and the basement stays dry. I want to finish the space out and am in a dilemma as to how to insulate. The foam boards definitely seem a great way to go but my precast walls have 6″ deep cavities, it has the look of like 18″ on center concrete studs, that’s the precast mould. Should I use the foam panels glued on each of these so called studs (which would leave a 6″ deep air cavity in every cavity), or should I cut 6″ foam strips and follow the concrete?? I hope you can picture what I’m describing. I could email you a pic if needed.

  64. Tadd


    Last year I found the builder put fiberglass insulation on the wall in my basement. I found it to be wet. Upon research I went with Pink rigid foam board against the wall and then studs and then fiberglass. we have not shetrocked yet and it has been sitting like this since last spring. I noticed around my window there was a little moisture on the concrete but I had not filled that in with spray foam yet. I decided to cut a little pink foam out 4 feet from the window and found it wet. I am at a loss. I have the box sill in that part of the basement filled with spray foam. Please help – how do I keep it dry.

  65. joe raffone

    I’m wondering, is it advisable to install rigid board a foot away from a filedstone wall – perhaps by fastening it to the side of the studs facing outside? I ask because I don’t want to pay for spray foam over the field stone, and I worry about the foundation rotting.

    I’d like to frame walls and slide the foam board behind the framing, then put roxul comfort between the studs. I’m not finishing the basement, I just want my floors to be warmer. I plan on sealing my ducts as well, and then wrapping them in insulation to get more comfort on our first floor.

  66. tim

    after using foam board against the outer walls should you use faced or un-faced insulation between the studs?

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  68. sulab

    Hi Todd- I have a unfinished basement which I am in middle of finishing with contractor help. The concrete wall was painted with water proofing paint. The stud wall (2×4) is already installed. Can I still install insulation board on the stud wall or it has to be done on concrete wall. Please advice. I am planning on using RMatte Plus 3 (closed cell polyisocyanurate foam with alluminium foils on both side)

  69. Wendi

    I appreciated your article. My contractors installed wood stud fur wall with batt insulation over 1″ rigid foam insulation over concrete retaining wall. Should I be concerned since the batt insulation was faced? It appears that the vapor barrier is on the drywall side. Sometimes it feels humid in this area so wondering if this is the problem and if we should remedy..

  70. J

    I have a walkout basement on a newer construction which they installed spray foam on the exterior do I need to have a interior vapor barrier as well? Also should I still glue foam in between my concrete wall and 2×4 framing wall?

  71. Brandon

    Hey, I just had the blow in blanket system used on my basement foundation walls in Edmonton Canada. I’m concerned about moisture growth now because the fiberglass is packed in touching the foundation wall. Have you ever used this product for a basement application. The installer told me that it is rated for basements. Any info would help, thanks

  72. Chad Collins

    Hi Todd,
    My Michigan home is 5 years old, poured concrete basement floor/walls. I have installed 2″ rigid foam and wood framing, now ready to install fiberglass insulation. I am seeing so many different opinions on using either faced insulation batts or plastic vapor barrier over unfaced insulation batts. First, should I be using a vapor barrier since I have 2″ rigid already and Second, if so should I be using the faced insulation batts or the plastic vapor barrier? Thanks!

  73. Charles Martin

    Hi Todd,
    We have a below ground basement in Colorado that is unfinished, with a structural concrete floor and concrete walls. The concrete walls are covered with fiberglass insulation backed with plastic. Would you recommend removing that insulation before framing and use the closed cell boards or spray foam?

  74. Steve Z

    Need help. Live in Wisconsin. Finishing basement.

    I have Water proof painted and sealed all basement walls and floor. Framed all walls which have 2″ gap from basement wall also. My questions…

    1) Do I still need to install poly roll as a vapor barrier or am I fine because of water proofed painted walls?

    2) In addition, I was planning to insulate framed walls with “faced insulation”. What side does the facing go? …toward drywall? …toward basement wall?

    Thank you !

  75. Michael Brousseau

    I have poured basement wall with a walkout in back. I used delta basement wrap on the outside to make sure water stayed off of basement wall. It has worked so far and the walls are dry. I have to finish the basement to be in compliance with the new laws on insulation seeing how its a open floor plan to the basement. Will the outside wrap work as a moisture barrier or do I still need to put a Styrofoam barrier on the inside to block the moisture on the studded walls. I live in Michigan so code requires the walls to be insulated to R-15. The building inspector said I could just stud and use Batt insulation but, it I would hate for the insulation to mold or get wet with moisture behind the drywall. let me know what you think as I have to start the project in the next few days to pass the inspection.

  76. Andy L

    Wow this is such an informative site! In part of my basement, I want to put in a 12′ work bench with pegboard behind it. My plan was to put 2″ XPS foam against the concrete foundation wall, then frame out a 2×4 wall and mount the pegboard on top. Now I realize that foam is supposed to be behind some type of fire barrier (like sheetrock).

    I’ve already got the foam board and cut it to size. What’s my best option going forward to avoid a fire hazard? Foam board, furring strips, sheetrock, then studs? Is there a better option? Thanks for your help!!

  77. Corey

    Great Article.
    I was wondering if I could get some advice on my particular situation. I’m finishing my basement in up-state New Hampshire (Franconia Area)
    Currently I have added 1.5″ Rigid foam adhered to the concrete foundation, on top of that I have 2×4 wood framing filled with unfaced Batt insulation. Rim-joists are spray foamed.
    I am currently deciding whether or not to install a poly vapor barrier on top of the framing/batt before I put up the drywall, or should I avoid that and put the drywall up as is.

    The basement is a walkout (1 wall 100% above ground, one fully under and other two 90% under sloping a bit as they approach the exposed wall) Any help is appreciated, thank you!

  78. Joe wiley

    Hello, I’m wanting to insulate my basement ceiling that has dampness. I saw a video where someone used foam boards and put the spray foam around it to hold it in place. it’s supposed to be more cost efficient. Is this solution ok to use or is there another option I should look into

  79. Jeff

    I was wondering what method should be done first? Spray foam sill plate 1st then put up xps foam board on walls or walls 1st then spray foam.
    Any help is appreciated, Thank you.

  80. Joh Bangs


    Basement is dry, exterior walls have been studded already with no insulation or VB on the exterior walls. Can I add batt insulation / paper out between the studs or is my only real option to spray foam the exterior walls. If spray foam how thick should it be? Live in the Boston area

    Thank You

  81. nancy blalock

    Thank you for the information Todd. I live in a cement earth house with the south side above ground. We recently had the south side replaced with new windows, doors and walls. My builder used cement board for the exterior wall (we’ll be doing stucco outside) and I was wondering if cement board, like concrete, soaks up moisture? Do I insulate it with foam boards? should I stay away from fiberglass insulation?

  82. Ed


    I have framed my basement walls, Vapour barrier is installed against the poured concrete basement wall. There is a 5 inch gap to the wooden studs. I am about to put in the insulation and my contractor has recommended pink fibreglass batts between the studs leaving an air gap between the pink and the vapour barrier on the concrete. The tack then clear plastic barrier to go on top. Question – is this OK?

  83. Francisco

    I am remodeling a small 5X7 bathroom in a 1979 home in Northern Virginia. The 5ft wide shower/tub wall was made out of tiled drywall over 1×3 fur, covered with old aluminum foil “insulation” (thin layer of aluminum foil facing the cinder block wall, and a layer of paper facing the drywall, with a thin layer of plastic in between). There is copper piping that goes through the wall at about 4ft to an exterior faucet (lots of cold air coming through). Bottom 3-ft are under ground level. Some 1×3 were molded at old tub level. A contractor recommended replacing the molded 1x3s and covering them with aluminum bubble wrap “insulation” before installing hardie backer boards. Hardie boards will be waterproofed with kerdi membrane. My two questions: 1) should I use 1/2 foam panel instead of bubble wrap? (Would love to use thicker foam but I am concerned about code clearances…. shower is already 28in deep only and with 15 in requirement from toilet to shower and vanity I don’t have any space to move the shower curb)… I’m not sure what would the AL bubble wrap accomplish for insulation. 2) Is it advisable to keep the exterior faucet behind the shower wall, or should I remove it? In either case, I’d seal the hole through wall with expanding foam.

  84. ashley

    Thank you for the article. Any advice on finishing a basement if the exterior of the foundation walls already have waterproofing, R-5 insulation, radon protection under slab? We are in zone 6 and recommends R13/19 insulation but if we add insulation of rigid to the interior and then frame out with drywall will the foundation be able to breathe? Or, are we better off not doing any interior insulation and just frame and finish out. Thanks in advance!!

  85. Chuck

    Hi Todd,

    I have a basement with 10″ thick poured concrete walls with 2″ exterior foam board insulation. I want to build 2″x4″ stud walls and cover with drywall. I am trying to maximize internal area and minimize cost. Since exterior is already insulated, can I use mineral wool between studs on the interior?

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    posts more,”pop”! Your content іss excellent but with imɑges and clips,
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    in itss field. Awesome blog!

  87. Jimmy

    My basement has been dry for sometime (been checking it for 6 months…no water). I glued foam board to the wall and now have water in one corner in particular. What could have caused this?

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