dcsimg

Raising height of raised garden beds

This topic contains 24 replies, has 9 voices, and was last updated by  GTokley 2 months, 2 weeks ago.

Viewing 5 posts - 21 through 25 (of 25 total)
  • Author
    Posts
  • #720483

    CB
    Pro

    Fine.

    Wives are always the boss, so I’ll rethink this to please her.

    This can be done entirely with wood and the lag screws or through bolts of your choice, and it can be made to look as if intentionally designed this way from the outset, although it will take a year or two to look as if built this way from the beginning, due to the weathering of the existing as built.

    In addition to the big 2×12 boards that make up your sides, you will need 288 board feet of 2×4, 96 board feet of 2×6, 96 board feet of 4×4… and for the ultimate in saturated soil weight stability, an optional 288 additional board feet of 4×4… all in the same species of lumber currently being used… for the integrated appearance.

    Setting aside the 288 optional board feet of 4×4 for the moment, let’s first discuss how to make use of the existing posts using the primary list of materials. This design presumes a deep and solid anchoring of the existing short posts, sufficient to resist the additional lateral pressure of 2 times the existing height.

    There are two types of posts in each planter bay. Corner posts and line posts. Let’s begin by building up the line posts.

    Cut eight 2′ long 2x4s. That consumed 16 board feet.

    Sandwich each line post with two of these 2×4’s, such that broad face of the added 2×4 mates directly wihh the 4×4 post, on either side, within the planter box.

    This means that external to the planter box, there will be no visual change, and internal to the planter box, there will be no further encroachment into the growing area beyond the extent that the existing 4x4s already encroach.

    The distinction here is instead of the 2×4 broad faces attaching to the side boards, they are attaching the line posts, serving as splints. You are essentially turning a 4×4 into a simulated 4×8, as seen in cross section from above.

    It will be like the 4×4 were raising it’s two 2×4 arms straight into the air.

    Cut four 1 foot long 4×4’s. That’s four board feet off of the essential material list.

    These short 4×4’s are the filler pieces to place in between the raised arms extending above each line post. At this point, the conversion of the 4×4 post into a simulated 4×8 post is complete. Through bolt the raised arms through the filler 4×4 that is resting directly on top of and inline with the existing 4×4 line post.

    Side screw (if the wife permits) the side boards into the narrow faces of the 2x4s, at even distances inbetween the through bolts that tie the two part post together.

    Then cross bolt the second layer side boards through the upper half of the cribbed line post, again allowing evenly distanced spacing away from the longitudinally oriented through bolts. Repeat for all line posts.

    Now, for the corner posts, the concept is the same, but being corners, the execution and the top cross section profile is different. Instead of simulating a 4×8, we will be simulating a 6×6 post at the corners.

    Cut four 2 foot long 2×6 pieces. Consumes 8 board feet of 2×6.

    Cut four 2 foot long 2×4 pieces. Consumes 8 board feet of 2×4.

    Take note of how the existing side boards are mated to the corner posts. You will want to make the next decisions based on your own sense of style, because you have a choice of which way to orient the 2×6 as well as the 2×4. I would chose a way that works visually in opposition with the way the existing long boards are attached, or better yet, with the way the subsequent long boards will be attached, which I recommend be the opposite of how the existing long boards are attached.

    I call what I am trying to describe a pin wheel pattern.

    With your design decision made, place the broad face of the 2×4 against one side of the existing 4×4 post, and place the broad face of the 2×6 against the other side 90 degrees away, such that the broad face of the 2×6 contacts the existing 4×4 as well as the narrow face of the 2×4 just added.

    At this point, you will have a pocket to drop in another 4×4 filler. Go ahead and cut four more 1 foot pieces of 4×4, consuming another four board feet off of the essential material list.

    Drop the 4×4 pieces in the “pocket” created by the 2×4 and 2×6 arms rising up at 90 degrees from each other… a pocket that will eventually be fully enclosed by the next layer of long boards that you add after the post augmentation is complete.

    As before, cross bolt, or lag screw, but cross bolting is stronger and can be re torqued in subsequent years as the wood shrinks. Space out the perpendicularly opposing cross bolts to leave enough virgin wood material in between clamping sites.

    Unlike the line posts, where the gardening happens, and were the post augmentation made no further encroachment into the growing space… the corner posts will be fatter as a result of turning them into simulated 6x6s. But since these are corners, the encroachment will not impinge on the growing space.

    This entire design is intended to leave the external sides as smooth as the original design, and unlike just tacking 2×4 braces directly to the long boards in the areas between posts, the lateral loads on the secondary layer of long boards are transferred directly to the lever in the ground afforded by the existing posts, again, presuming the existing posts were set well.

    Which brings us to the optional part… the extra 288 board feet of 4×4.

    There are 8 existing posts per planter box, leaving 6 “open” four foot wide areas where no posts exist. You can evenly divide each of these four foot wide open spaces by setting an additional post, 4 feet long, two feet in the ground, two feet above ground.

    By evenly splitting each of the open spans between existing posts, it will look as if posts the 6 new 4×4 line posts (which will be REAL posts) were intermediaries between the simulated 4×8 line posts and simulated 6×6 corner posts.

    The end result will be a very robust raised bed that will not require any tear out of the existing, and will aesthetically match the simple architecture, offering zero evidence on the external face of the augmentation.

    With the line post splints oriented broad face toward the posts, rather than toward the long boards, the wider x4 dimension of the 2×4 is invoked against the bow out load of soil acting on the secondary long board…. rather than the narrower x2 dimension of the brace taking that load.

    #720484

    Sprokitz
    Pro
    Eastern shore of, Pa

    I’d love to use 2×4 verticals as gussets. My wife is the one who is very concerned with appearances and we were looking to have these look like they were built higher to start with by extending the vertical posts. Thanks for all of the suggestions.

    My take, get some rebar and a long auger bit. Bore down in each corner post about 12″ keeping the hole plumb. Cut 4 pieces of new post longer than needed and bore holes in each about 8″ deep. Cut 4 pieces of rebar 19″. Pound one in each existing post, then drive new post sections onto the rebar. Measure and cut new add-on posts to desired height. Dig down and add 2X4’s (3) in between existing 2Xs. Screw new side boards to posts and 2X’s. Fill with your favorite dirt and grab a beer.
    I see no reason why doing that wouldn’t hold the amount additional soil that will be added and that soil will “hide” the existing 2X’s so the wife should be happy

    #720485

    Boschmanbrian
    Pro
    Montreal , QC, Canada

    I’d love to use 2×4 verticals as gussets. My wife is the one who is very concerned with appearances and we were looking to have these look like they were built higher to start with by extending the vertical posts. Thanks for all of the suggestions.

    My take, get some rebar and a long auger bit. Bore down in each corner post about 12″ keeping the hole plumb. Cut 4 pieces of new post longer than needed and bore holes in each about 8″ deep. Cut 4 pieces of rebar 19″. Pound one in each existing post, then drive new post sections onto the rebar. Measure and cut new add-on posts to desired height. Dig down and add 2X4’s (3) in between existing 2Xs. Screw new side boards to posts and 2X’s. Fill with your favorite dirt and grab a beer.
    I see no reason why doing that wouldn’t hold the amount additional soil that will be added and that soil will “hide” the existing 2X’s so the wife should be happy

    That sounds like a good idea again nothing to costly and will keep the look without changing

    #720662

    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    If you want to go the econo route just set a 2x6or 8 or 10 or whet ever on top and use a 2×4 vertical every 3 feet or so as gussets. Pau you’re done.

    Translation please!

    what part??

    Dirty

    A Working Pro since 1988!

    Member since January 26, 2013.

    #720763

    GTokley
    Pro
    Madoc, ON

    I’d love to use 2×4 verticals as gussets. My wife is the one who is very concerned with appearances and we were looking to have these look like they were built higher to start with by extending the vertical posts. Thanks for all of the suggestions.

    My take, get some rebar and a long auger bit. Bore down in each corner post about 12″ keeping the hole plumb. Cut 4 pieces of new post longer than needed and bore holes in each about 8″ deep. Cut 4 pieces of rebar 19″. Pound one in each existing post, then drive new post sections onto the rebar. Measure and cut new add-on posts to desired height. Dig down and add 2X4’s (3) in between existing 2Xs. Screw new side boards to posts and 2X’s. Fill with your favorite dirt and grab a beer.
    I see no reason why doing that wouldn’t hold the amount additional soil that will be added and that soil will “hide” the existing 2X’s so the wife should be happy

    This does sound like a pretty good way of doing it. Doesn’t create alot of work or cost much money.

    Greg

    instagram.com/gregtokley/

Viewing 5 posts - 21 through 25 (of 25 total)

You must be logged in to reply to this topic.

queries. 0.315 seconds