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Thread: State of Sheet Goods

  1. #1

    State of Sheet Goods

    Saw another member's post about a gate which he replaced which kinda prompts this post.
    When we bought our place PO had OSB doors on a corrugated metal add-on shed
    (added on to the 12'x24' metal building that is my shop). Thing was he had the OSB sheathing on
    the back of 2x4 framing. The water ran down the OSB, sat on the bottom rail and result was obvious.
    One of my first projects was removing the doors, stripping all the OSB off which wasn't real hard due to
    extensive rot, and repairing the 2x4 frames and re-sheathing the doors. Went to Home Depot and got
    T-111. Primed it with double coat of prime (and paint) on all edges as well as front and back. Have done at least one re-paint. Exterior Latex Semi-Gloss to try to hold down mildew. Now just a few years down the road I have rot on both doors at the bottom strap hinges. I try to look at the edges of sheets for voids when purchasing but trying for flawless lumber these days means you haven't put anything on the cart.
    Guess my point or question/s are:
    Is it un-realistic to expect an exterior rated sheet good to hold up more than 5 yrs+- when primed and painted properly?
    What are my alternatives in "man-made" Hardi-board sheet good?

  2. #2
    Mike,

    I had to replace the double doors on my shed after 20 years of the bottoms getting soaked when our winter snow melted. The originals were tongue and groove pine with simple battens and diagonals on the back to prevent drooping. The lower end of the doors with the exposed end grain was the problem. They soaked up water, swelled making the doors often difficult to open, and eventually caused rot.

    When I replaced them with new doors I continued with the tongue and groove pine/fir. The difference was that this time I used slotted top and bottom boards about 6" wide. The tongue and groove was tenoned on the ends and slipped into the slots. Soaking the end grain of everything in Minwax Wood Hardener and then priming before assembly made a big difference.
    Dave Anderson

    Chester, NH

  3. #3
    Join Date
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    Quote Originally Posted by Mike Hutchison View Post
    Saw another member's post about a gate which he replaced which kinda prompts this post.
    When we bought our place PO had OSB doors on a corrugated metal add-on shed
    (added on to the 12'x24' metal building that is my shop). Thing was he had the OSB sheathing on
    the back of 2x4 framing. The water ran down the OSB, sat on the bottom rail and result was obvious.
    One of my first projects was removing the doors, stripping all the OSB off which wasn't real hard due to
    extensive rot, and repairing the 2x4 frames and re-sheathing the doors. Went to Home Depot and got
    T-111. Primed it with double coat of prime (and paint) on all edges as well as front and back. Have done at least one re-paint. Exterior Latex Semi-Gloss to try to hold down mildew. Now just a few years down the road I have rot on both doors at the bottom strap hinges. I try to look at the edges of sheets for voids when purchasing but trying for flawless lumber these days means you haven't put anything on the cart.
    Guess my point or question/s are:
    Is it un-realistic to expect an exterior rated sheet good to hold up more than 5 yrs+- when primed and painted properly?
    What are my alternatives in "man-made" Hardi-board sheet good?
    Depends on how wet the plywood gets an how long it stays wet. Anything but marine plywood is not intended to get wet and will eventually delaminate. Good marine PW is very pricey.

    If you can buy US or Canadian made T-111 you stand a better chance of getting effective exterior glue. But even great ext-grade plywood will delaminate if it suffers enough cycles of wet/dry.

    You might want to consider priming and painting the plywood with a very good quality exterior latex paint/primer after cutting but before nailing/screwing the plywood to the frame, allowing it to really soak into the edges, and follow up with a topcoat of latex after installing. Don't forget to caulk the hell out of it. Its easier to give it a really good paintjob before assembly.

    One fix would be what boat builders do: wrap the bottom edge of the plywood in glass mat and polyester resin followed by a good UV proof paint. Ugly.

    Hardi board would work long term, but its a pain to install and quite heavy.

    I made 12' high replacement double doors for a friend's Amish-built horse barn this way. I built a framework with the lower rails/stiles of pressure treated lumber, and covered this with T&G pine boards oriented diagonally similar to what Dave Anderson described. I don't recall the designation of the boards, but they had a moulding detail on the face. I used hot-dipped galvanized clips at the four corners, and hot-dipped galvanized twisted nails (pallet nails or decking nails). I also installed a galvanized drip strip on the exterior bottom of the doors to keep water running down the face of the doors from wetting the bottom of the doors. My friend told me the metal flashing I installed was too flimsy though and it got pretty torn up by farm equipment and horse shenanegins so he installed a replacement made from heavier gauge A-36 bent plate with just a primer coat. It seems to have been effective in protecting the doors from more than just rain/snow according to him.

    Of course, I caulked all the joints thoroughly, and painted it with the best primer and exterior grade latex paint I could find. Scott touched it up every fall until he sold his horses and the property last year. It seems to have held up pretty good, but it has been less than twenty years. The doors are much better made than the barn.... but doors take a lot of abuse so I think it was worth the trouble.

    For what it is worth.

    Stan

  4. #4
    Another option would be the MDO 'sign board' .Plywood covered with impregnated paper fiber.Ive tested it by repeatedly soaking and drying samples and never seen it come apart. Mfg. says to cover the edges but sign makers often don't. It is expensive but cheaper than marine plywood,since it may have small inside voids. I only use the good both sides stuff,stays flatter. Has real high rating for holding paint.

  5. #5
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    Not trying to be overly contrarian, but I think the design is the problem. Reverse the plywood (I would use marine plywood) to keep water from standing on the lower member. Think about how many houses are designed. Water is to run off the siding and then away from the house. Just one man's opinion.
    Shawn

    "no trees were harmed in the creation of this message, however some electrons were temporarily inconvenienced."

    "I resent having to use my brain to do your thinking"

  6. #6
    Input much appreciated as this project is next on the list. Guess I should have stated the first thing that changed on
    the rebuild was the T-111 went on the outside of the framing of doors. Also in the interest of full disclosure I am in
    Florida so there is a lot of rain. In any case, think I will get the edge/s of any plywood covered with 1x4 flat "face frame"
    and maybe look into the Min-Wax Wood hardener.

  7. #7
    Advantech resists rot well; swell is minimal. I have used it for two utility trailer floors that are left outside. Very durable, but I've never tried to paint it.

  8. #8
    If you have some one who sells it around where you live 4x8 PVC board would hold up pretty good. Won't rot anyway. Paint stays on that stuff forever it seems. The downside is the cost but over the long haul it is worth it.

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