bglenden Posted August 3, 2017 Report Share Posted August 3, 2017 I am thinking of building a camping stuff organization system for the bed of my truck out of plywood (metal would be better, but I know how to make stuff out of plywood!). When driving it would be under cover (tonneau) but when camped it would be exposed to the elements, i.e. it could get rained upon fairly steadily for a day or so at a time. How would you guys make it waterproof? Is there some kind of paint/goop that I can put on? I think plywood boats usually have fiberglass layer(s) over them (seems like overkill)? Any suggestions? (I don't care about appearance for this application). My understanding is that marine grade plywood is not actually waterproof (plus, who knows where I'd get it in a small town in the middle of the desert!). Quote Link to comment Share on other sites More sharing options...
rodger. Posted August 3, 2017 Report Share Posted August 3, 2017 Our local HD sells pressure treated plywood. Would that be adequate? Quote Link to comment Share on other sites More sharing options...
bglenden Posted August 3, 2017 Author Report Share Posted August 3, 2017 7 minutes ago, rodger. said: Our local HD sells pressure treated plywood. Would that be adequate? I don't know for a fact, but suspect that while it wouldn't rot it would swell, so it wouldn't be good for having doors and maybe drawers. Quote Link to comment Share on other sites More sharing options...
Popular Post wdwerker Posted August 3, 2017 Popular Post Report Share Posted August 3, 2017 Just use exterior ply and exterior paint. Caulk all joints, inside and out. Design construction to prevent a vertical seam from collecting water. We had a plywood camp kitchen box for camping and the door swung down to be a work surface. The top overhung all sides by an inch or so. It survived for years of use by our custom van club. Just open it up and allow it to dry before storing. Put some feet/spacers underneath so it's not sitting in water on the truck bed. 4 Quote Link to comment Share on other sites More sharing options...
wdwerker Posted August 3, 2017 Report Share Posted August 3, 2017 We used 1/2" and 3/4" yellow pine exterior ply, yellow glue and exterior screws. The piano hinge did rust quickly but still worked fine, just cosmetic appearance. Quote Link to comment Share on other sites More sharing options...
treesner Posted August 3, 2017 Report Share Posted August 3, 2017 i've given some thought to working with ply outdoors. I was thinking finishing the piece in epoxy would probably work well. For my outdoor (solid wood) shave horse the advice was to epoxy the end grain of the feet that touches the ground. 1 Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted August 4, 2017 Report Share Posted August 4, 2017 Steve is on the right track. Build it like a house, so it sheds water, and paint it thoroughly. My grandfather used to keep a "dog box" in the back of his pickup, for going 'coon hunting. He laid a sheet of aluminum over the top, folded over the edges, and tacked it down about 1.5" below the edge. Keeping water from standing on top, and keeping the box from sitting in a puddle, goes a long way. Even without paint. Quote Link to comment Share on other sites More sharing options...
Jean [Fr] Posted August 4, 2017 Report Share Posted August 4, 2017 If you want your outdoor plywood furniture to last, you should use marine grade ply. It worth the extra bucks. There's two different ways to bring up the topic. First method, you want to seal the wood. You need an extra strong finish and no leak at all for the wood to keep its initial moisture level. IMHO paint is not the proper way to go, because it only seals by numbers of coats and you need to maintain the paint each year with some new layers. I prefer UV resistant crystal epoxy. It really seals the wood with a single coat and is lifetime. You can polish the surface several times if you get some unwanted scratches. On the other hand, this is a glossy plastic look some people would not like. Second method, you want to allow the wood to breath. Even if plywood is a stable material, it can last a lot with a light breathy finish and an annual care. You can use hard oil (like teak oil). It's more natural to the touch and it can stand rain and moisture. Apply in at least 3 coats. I like to warm up the oil to 60°C (140°F) for the first applications. It goes deeply into the grain and will protect the wood definitely. The first coat can be heavy, but don't over charge. Do some tests to figure out the right amount. After winter time, just do a light sanding (P240) and apply a new coat of hard oil, and it will last for the year. This is a really fast process and your furniture will look as new. Quote Link to comment Share on other sites More sharing options...
Orbb Posted August 4, 2017 Report Share Posted August 4, 2017 Epoxy on plywood will work. Fiberglass is not necessary unless you need it for strength. 1 Quote Link to comment Share on other sites More sharing options...
Alan G Posted August 4, 2017 Report Share Posted August 4, 2017 I think Marine grade ply and some Epifanes would make that weather proof. Quote Link to comment Share on other sites More sharing options...
GeneT Posted September 7, 2017 Report Share Posted September 7, 2017 You should consider MDO. Will probably need to purchase from a plywood supplier. https://www.andersonplywood.com/395/mdo-medium-density-overlay/ Quote Link to comment Share on other sites More sharing options...
drzaius Posted September 7, 2017 Report Share Posted September 7, 2017 8 hours ago, GeneT said: You should consider MDO. Will probably need to purchase from a plywood supplier. https://www.andersonplywood.com/395/mdo-medium-density-overlay/ +1 on the MDO. I had to replace the jambs on my garage door several years ago & used MDO ply. I sealed the bottom couple of inches with epoxy where it touches the concrete. It's on a north elevation where it never gets any sun & the concrete is almost always wet in winter. So far it looks as good as new. Quote Link to comment Share on other sites More sharing options...
wdwerker Posted September 7, 2017 Report Share Posted September 7, 2017 MDO is awesome stuff ! Around here they call it sign painters board. The MDF faces are made with lots of exterior resin and paints up beautifully. It's heavier than exterior ply & costs more but it's flatter and so easy to finish. Do pay attention to sealing up edges and keep them slightly elevated from sitting in water and it lasts for years in the weather. Quote Link to comment Share on other sites More sharing options...
drzaius Posted September 7, 2017 Report Share Posted September 7, 2017 1 hour ago, wdwerker said: Do pay attention to sealing up edges and keep them slightly elevated from sitting in water and it lasts for years in the weather Yes, I forgot to mention that I painted epoxy on all the edges that are exposed to weather as well. MDO also seem quite a bit stronger than ordinary ply. Quote Link to comment Share on other sites More sharing options...
Ronn W Posted September 7, 2017 Report Share Posted September 7, 2017 Would MDO be a better product ot use for Table saw sleds etc. Even Baltic pirch plywood is not so straight sometimes. 1 Quote Link to comment Share on other sites More sharing options...
drzaius Posted September 7, 2017 Report Share Posted September 7, 2017 3 hours ago, Ronn W said: Would MDO be a better product ot use for Table saw sleds etc. Even Baltic pirch plywood is not so straight sometimes. I've only seen MDO in 3/4" & that's a bit heavy for a sled. I suppose they make it thinner though. Quote Link to comment Share on other sites More sharing options...
wdwerker Posted September 7, 2017 Report Share Posted September 7, 2017 I would think MDO is a bit much for a sled unless you have a scrap on hand. They might make it in 1/2" but I've never seen it. Quote Link to comment Share on other sites More sharing options...
Marmotjr Posted September 8, 2017 Report Share Posted September 8, 2017 The 2 huge doorways we're making at work, the internal structure is all MDO with some mahogany dimensional lumber, and will be encased in mahogany solids for the painting surface. It's really nifty stuff. 1 hour ago, wdwerker said: They might make it in 1/2" but I've never seen it. We have a couple pallets of it in the shop. Doing a quick google search, it appears it's available at Menards..... Quote Link to comment Share on other sites More sharing options...
Coop Posted September 8, 2017 Report Share Posted September 8, 2017 Never heard of this stuff. Is it heavier than ply and if so, approx. how much more? Quote Link to comment Share on other sites More sharing options...
wdwerker Posted September 8, 2017 Report Share Posted September 8, 2017 Maybe 20 % I guess . The stuff I have is quality yellow pine core (damn near voidless ) with maybe 1/8 MDF faces. 1 Quote Link to comment Share on other sites More sharing options...
Marmotjr Posted September 8, 2017 Report Share Posted September 8, 2017 It's basically a ply core, and instead of the outer veneer being wood, it's 1/8"ish of mdf. It's heavy, sturdy, cuts clean like mdf, but holds screws like ply. I've enjoyed working with it. 1 Quote Link to comment Share on other sites More sharing options...
Minnesota Steve Posted September 8, 2017 Report Share Posted September 8, 2017 Marc used this Totalboat Epoxy on his outdoor table when he refinished it in one of his recent videos, followed with epifanes. Watching that Tips from a Shipwright boat build... he used a Totalboat epoxy primer and paint. That looked pretty durable.. Quote Link to comment Share on other sites More sharing options...
drzaius Posted September 8, 2017 Report Share Posted September 8, 2017 I understood that the face layers of MDO consist of phenolic impregnated paper. The stuff I've got in the shop definitely doesn't have MDF as the outside layer. Quote Link to comment Share on other sites More sharing options...
wdwerker Posted September 8, 2017 Report Share Posted September 8, 2017 Laminate is made of high pressure phenolic papers. It's usually 1/32 or less thick. The MDO faces are definitely thicker than that and they have a much higher level of resin in them & they aren't as hard & dense. MDF is kind of like a thicker sheet of paper. So maybe the MDO faces are between the two. There is also HDO which has smoother & harder faces. Some places have exterior MDF or HDF which paints well but I have no idea how long it lasts. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted September 8, 2017 Report Share Posted September 8, 2017 Norm used MDO on all sorts of outdoor projects. Personally, I have never seen it in any of the home centers or lumber yards in my area. Quote Link to comment Share on other sites More sharing options...
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