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Waterproofing Deck over occupied Space

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  • #588911
    DIYPro
    Pro

    I am in the process of replacing a deck from the second floor. This is a bad construction from the beginning, which we discovered few years after purchasing the house. When the house was built apparently deck was installed such that 4’x6′ section of it is over the occupied space, another words part of the lower level family room is open to the outside environment. We need to re-enforce the floor joist that is extending from house to under the deck because moisture damaged parts of the board.
    Once the joists are fixed and structurally sound, I was planning to do the following:

    1. Install pressure treated ply wood over the joists
    2. install flashing against the house and wrap the side of the deck with flashing
    3. Waterproof the entire deck including the flashing
    4. Install tongue and groove composite by gluing the compost on the membrane. I do not want to use nails or screws because I do not want to puncture the membrane to ensure the integrity of the waterproofing
    5. Seal the top

    Key thing on this project is to waterproof the floor to ensure moisture will not penetrate and damage the sub-floor.

    I have never did waterproofing over the occupied space that is open to the outside environment. I am not sure if what I outlined above is the right way to fix this deck. If any of you have done similar projects with success, I would appreciate any recommendations you may have. Is the composite tongue and groove be glued on or can it be glowed on?
    Thanks

    #588936
    BeardedCarpenter
    Pro
    Winsted, CT

    I’ve seen a few similar things like this recently: a porch over a basement, and front steps and landings over the basement. It’s a stupid design. It’s already been built so there’s not much that can be done to truly reverse the bad design.

    I think you’re on the right track by basically making a flat roof over the living space. I’ve helped by boss do that a few times. There’s really not much else you can do.

    My one suggestion is to do more research about gluing the composite decking to the rubber. It might work, but something about it makes me hesitate.

    Are you able to go any higher than the current deck height? Whenever we’ve put decking or flooring over rubber, we’ve put down sleeper joists on the rubber (usually pt 2x4s laid flat), and fasten the decking to the joists. The whole thing simply floats on the rubber.

    #588941
    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    Hello Miss DIY Pro. Once you have the framing ripped out and repaired properly I would have a roofing company put down a membrane may be TPO. They should give you a good warranty with a product it’s very good. Then I would do as the gentleman above stated put down sleepers and attach the decking the sleepers. I would do it in sections that could be lifted out in case something with the membrane fails it can be redone or repaired in 20 years.

    #588953
    Austin
    Pro
    Covington, KY

    I have done a couple like this and every time it’s as the way mentioned above. Below the deck surface it’s treated as a flat roof so the roofing company puts a rubber membrane down then a pressure treated 2×4 grid is built and put down as a sleeper and not nailed or screwed in any way and that way the decking material can be fastened to that.

    #589259
    redwood
    Pro

    I’ve done a fair number of these decks over the years. Obviously the membrane, slope and ways to get the water off the roof are the keys. I can’t say it won’t work (but I doubt it), glueing the decking to the membrane does not sound good to me. Sleepers are the most common method, by far.

    Mark E.

    Pioneer, CA

    Working Pro 1972 - 2015
    Member since Jan 22, 2013
    www.creative-redwood-designs.com

    #593392
    Stilla
    Pro

    i agree with all the above contractors. i want to add that flat roofs are prone to ice damming, as the heat from the interior space heats the membrane. the ice that forms just above the membrane will melt, the roof needs enough pitch so it can discharge the water. its best that the water does not drain into a gutter as it will flash freeze, as the gutter is not warmed by the interior spaces. its a tricky fix when it comes to cold weather. in some cases i have had to place heaters in the gutters as there was no cheap resolve.

    #593401
    Stilla
    Pro

    I’ve done a fair number of these decks over the years. Obviously the membrane, slope and ways to get the water off the roof are the keys. I can’t say it won’t work (but I doubt it), glueing the decking to the membrane does not sound good to me. Sleepers are the most common method, by far.

    what are those black cylinders you are using under those huge sleepers, is this a decking system for flat roofs? i have never seen that. i can see they have different shapes, and the finished deck has a number of objects i would think are shims for what i think is a system?

    #593405
    Warren6810
    Moderator
    Akron, OH

    We have done several of those as well. An EPDM membrane is installed by the roofer, then sleepers, then decking. We lay 2×4 treated flat on the membrane and it has worked well.

    #593440
    redwood
    Pro

    I’ve done a fair number of these decks over the years. Obviously the membrane, slope and ways to get the water off the roof are the keys. I can’t say it won’t work (but I doubt it), glueing the decking to the membrane does not sound good to me. Sleepers are the most common method, by far.

    what are those black cylinders you are using under those huge sleepers, is this a decking system for flat roofs? i have never seen that. i can see they have different shapes, and the finished deck has a number of objects i would think are shims for what i think is a system?

    Those are Bison adjustable deck supports. A really neat and quick leveling system, but costly.

    http://www.decksdirect.com/more-deck-products/bison-deck-supports

    Mark E.

    Pioneer, CA

    Working Pro 1972 - 2015
    Member since Jan 22, 2013
    www.creative-redwood-designs.com

    #593462
    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    what are those black cylinders you are using under those huge sleepers, is this a decking system for flat roofs?

    They are often use on slopping concrete and are easy to level out for the deck. As RW said they are pricey but when the plans call for them that the way it goes.

    #594139
    Stilla
    Pro

    what are those black cylinders you are using under those huge sleepers, is this a decking system for flat roofs?

    They are often use on slopping concrete and are easy to level out for the deck. As RW said they are pricey but when the plans call for them that the way it goes.

    I’ve done a fair number of these decks over the years. Obviously the membrane, slope and ways to get the water off the roof are the keys. I can’t say it won’t work (but I doubt it), glueing the decking to the membrane does not sound good to me. Sleepers are the most common method, by far.

    what are those black cylinders you are using under those huge sleepers, is this a decking system for flat roofs? i have never seen that. i can see they have different shapes, and the finished deck has a number of objects i would think are shims for what i think is a system?

    Those are Bison adjustable deck supports. A really neat and quick leveling system, but costly.

    http://www.decksdirect.com/more-deck-products/bison-deck-supports

    That system is really neat.

    #594176
    DIYPro
    Pro

    Thank you everyone for the information. Based on the recommendations, we will do the sleepers. Next critical thing I need to find is the best waterproofing membrane over the occupied space. Please keep in mind that all the support structure used on this project is wood. They are the 2″x12″ joists extending from the 2nd floor of the house. I need to find a product that will waterproof the entire floor below the sleeper floor. Does anyone know what product is the best over the occupied space?

    #594228
    redwood
    Pro

    In reality, I don’t think anyone here can suggest such a product without seeing the site and local. Personally, I had over 38 years exp as a carpentry contractor with a emphasis on outdoor construction. Sorry, but I don’t feel this is a DIY project. It only takes one small error to turn this into a horrific project.

    I would suggest you contact a local roofer, experienced in such projects. The decking you can do yourself.

    Mark E.

    Pioneer, CA

    Working Pro 1972 - 2015
    Member since Jan 22, 2013
    www.creative-redwood-designs.com

    #594299
    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    Sorry, but I don’t feel this is a DIY project.

    RW is right, a good waterproofing specialist is what you need and ask them about TPO (Thermoplastic polyolefin).
    http://firestonebpco.com/roofing/tpo-roofing-systems/

    #594310
    DIYPro
    Pro

    Thank you guys, I will talk to a roofer who has done such projects for waterproofing.

    #645296
    DIYPro
    Pro

    Hello everyone. Some time passed since I posted on this topic because I was tied up with another project. Now I am getting back to this one.

    Considering to use AMES Products designed for roof decks over living space:
    1. Install marine grade plywood over the joists
    2. Tape the joists with Seam Tape
    3. Prime with Super Primer (2 coats)
    4. Apply Elasto Berrier with Contouring Roofing Fabric (2 coats)
    5. Apply Maximum Stretch
    6. Top Code with Safe-T-Deck (2 coats)(This is similar to what they apply to garage floors)
    7. Mount the railing from sides of the deck with Aluminum sections in between

    Has anyone used AMES products? Is there any other product that is better for this application?

    Thank you in advance for your input

    #645340
    jkirk
    Moderator
    halifax, nova scotia

    if you can its best to float rooftop decks and not fasten them.. the framework should allow water to pass through/ under it for run off and have zero penetrations which will leak..

    redwoods design is the best i know of. as for gluing down composite… it wont work, it might hold for a few months after one freeze thaw cycle guarenteed it will loose its bond

    heres a tip, dont fart in a space suit

    #645370

    if you can its best to float rooftop decks and not fasten them.. the framework should allow water to pass through/ under it for run off and have zero penetrations which will leak..

    redwoods design is the best i know of. as for gluing down composite… it wont work, it might hold for a few months after one freeze thaw cycle guarenteed it will loose its bond

    I’m with you on the glue down on the composite decking . With the season change that board will move like crazy .

    Always willing to learn .

    #645382
    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    Hello everyone. Some time passed since I posted on this topic because I was tied up with another project. Now I am getting back to this one.

    Considering to use AMES Products designed for roof decks over living space:
    1. Install marine grade plywood over the joists
    2. Tape the joists with Seam Tape
    3. Prime with Super Primer (2 coats)
    4. Apply Elasto Berrier with Contouring Roofing Fabric (2 coats)
    5. Apply Maximum Stretch
    6. Top Code with Safe-T-Deck (2 coats)(This is similar to what they apply to garage floors)
    7. Mount the railing from sides of the deck with Aluminum sections in between

    Has anyone used AMES products? Is there any other product that is better for this application?

    Thank you in advance for your input

    That sounds like a good plan. I have not used that brand but it should work. I don’t know why the marine grade plywood, man that must be expensive.

    #645397
    smallerstick
    Pro
    North Bay, ON

    It’s been some time since I did a deck over living space, but I had a roofer do a tar and gravel roof with blocks set into the built up roof. The conventional deck was built on top of those sleepers.

    No problems during the time I lived in the house.

    Good luck with the project.

    BE the change you want to see.
    Even if you can’t Be The Pro… Be The Poster you’d want to read.

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