Non-marine plywood outside

Re: Non-marine plywood outside

William Duffield, on the Cohansey


>Most plywood you can buy nowadays is made with waterproof glue, so all is not lost before you even get out of the gate (Not ParaPly, and not the stuff made from rice noodles that the Chinese use for shipping crates for cast iron woodworking machinery). I prefer a two-step treatment for things I want to use outdoors and want to keep, but for these, I don't start with plywood. First, to seal the surface to keep water from penetrating, I apply a coat of epoxy, usually West System, applied with a brush or roller. After it has started to cure (overnight), I apply a few coats of spar varnish with UV inhibitors. I like Sikken Cetol. You can't use epoxy by itself outdoors, because the UV rays from the sun quickly deteriorate it.

BTW, the finishes I have recommended will cost you a lot more than the plywood. Have you considered a concrete table top, instead of plywood? Later, you could make it look fancier by covering it with ceramic tile.

Re: Non-marine plywood outside

Dave (Arlington, VA)


>Hi William -

Thanks for the recommendations... and I didn't know that the glues nowadays were waterproof, but I assume that you might get some delamination if the end grain around the edges get wet and begins to swell.

Funny you should say...mosiaic - 'cause someone in our family has mentioned this possibility.

It's so sad that the glass top we previously had on our table recently and completely shattered (I believe the engineer lingo on this is "catastrophic failure") into thousands of tiny pieces without any evidence of external forces...e.g. one of my kids baseballs, etc.

Thanks for the ideas!

Dave

Re: Non-marine plywood outside

Dave Thompson


>Hi Dave, I'm not clear whether this item already exists and you need an outdoor varnish, or are making it and are chosing the materials....

MDO (Medium density overlay) is plywood intended to be painted for outdoor use. I have some painted MDO that has been outside exposed for the past two years without any noticible change. It is more expensive than oak veneer plywood, fwiw.

If you already have something made and want to coat it, have you considered marine epoxy? I haven't tried this myself. For my wood front door, I use sparathane, which is like an outdoor polyurethane with UV inhibitors. It's common at most borgs. It holds up well, but probably needs touching up every once in a while.

good luck,

Dave

Re: Non-marine plywood outside

Victor P


>here was my solution...not very elegant, but has held up well for about 16 or 17 years now.

Victor In Houston where we had a brief shower the other day. :>)

What happens when it really rains? ;-)

Dan Donaldson

Re: Non-marine plywood outside

William Duffield, on the Cohansey


>If you've got a cement and mosaic top, at least it won't float off into the neighbor's yard. A matrix of rebar wouldn't hurt either :^)

Re: Non-marine plywood outside

Victor P


>I forgot to mention that the plywood top has a nice thick sheet aluminum as a cover. I had it off last summer to rebuild the seats. The plywood was showing some rot at the corners only, otherwise it was sturdy enough to put back on completely rebuilt base.

Regarding the rain:

We had eight inches of rain in two days. This picture is of our shop property several miles from my house. It usually drains off pretty fast, but a neighbor recently cleared his lot off and the rain washed a bunch of debris into the ditch clogging up an outfall to the flood control ditch about 50 feet from our fence. Once the obstruction was removed our lot and a couple of neighbors on the other side of us drained in about an hour. The worst of the Houston floodng was about three miles north of our shop and made the national news (slow news day).

I was the only one in our small company that managed to make it into work that day.

Regards,

Victor