Exterior Options

[HotRod1]

As someone who builds cedar strip and planked boats I vote for wood if you want that. Use 4oz fiberglass cloth used for boats, it has a tight weave and will disappear when the epoxy is applied. The glass comes 60" wide and any length you want. If you use a slow cure hardener you can get all the bubbles out before it hardens. It makes a mess so put down plastic before you start. West Systems sells all the materials you need. You will end up with the wood sealed and won't have to worry about it. You will need to use a spar varnish on it after the epoxy for uv protection, but that will add to the beauty of the wood.

One more thing, make sure the glass is shipped rolled and never fold it. It is almost impossible to get the creases out once they are there.


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[rruff]

So after doing some reading and more looking, here is my thought. 1/8" birch which will be covered with maps as my wallpaper; 1/4" (??) foam or insulating material; exterior I'm thinking of splurging on this and go with mahogany. So I would use a clear varnish then along with other weather resistant material?? I'm looking at making the doors as well and possibly use a lighter color than mahogany - just to give some character.

If you want the wood look and insulation, I'd go with a sandwich of thin marine ply outside 1/2-1" XPS foam from the big box. Cover with a layer of fiberglass cloth and epoxy, and varnish.

If you like that idea I can suggest places to get the materials.

[dakippen]

So after doing some reading and more looking, here is my thought. 1/8" birch which will be covered with maps as my wallpaper; 1/4" (??) foam or insulating material; exterior I'm thinking of splurging on this and go with mahogany. So I would use a clear varnish then along with other weather resistant material?? I'm looking at making the doors as well and possibly use a lighter color than mahogany - just to give some character.

If you want the wood look and insulation, I'd go with a sandwich of thin marine ply outside 1/2-1" XPS foam from the big box. Cover with a layer of fiberglass cloth and epoxy, and varnish.

If you like that idea I can suggest places to get the materials.

I'm actually going to use mahogany for the exterior - I really like the look and I think when treated properly, it'll be very nice.

[rruff]

I'm actually going to use mahogany for the exterior - I really like the look and I think when treated properly, it'll be very nice.

Sounds nice! Boards, laminate, plywood?

[dakippen]

I'm actually going to use mahogany for the exterior - I really like the look and I think when treated properly, it'll be very nice.

Sounds nice! Boards, laminate, plywood?

Mahogany covered plywood...

[rruff]

Mahogany covered plywood...

So plywood is your shell material, and mahogany boards your external covering?

[dakippen]

Mahogany covered plywood...

So plywood is your shell material, and mahogany boards your external covering?

I went to the lumber yard, asked for mahogany, and it came as the mahogany over plywood, 1/4" thick....

[Atomic77]

Isn't it fun figuring out all these little details? And just as you figure out one another will pop up to take it's place! Enjoy the journey my builder friend...

I think you're on the right track. If I were to make a recommendation, I would go with 1/4" plywood with the mahogany veneer to get the look you want. Study up on some of the techniques on this forum for a sandwich style wall. Don't overbuild it. Two 1/4" pieces of plywood with a plywood skeleton between is a good choice. Foam inside the skeleton. I honestly think you could just sandwich foam and it would be fine. Just haven't personally done it but I've seen it done here. As far as the interior finish, spar varnish will look great. But on the outside don't skimp. You'll regret it. I've seen some failures and trust me you want to do it right the first time. A re-do sucks. Bad. And it's money down the crapper. Study up on epoxy. There's no substitute for a glass and epoxy exterior. I'm a coatings specialist and I wouldn't even think of just varnish or the like for a time honored finish. Go to youtube and check out some of the plank canoes and how they lay up the cloth and epoxy. As someone else already said you'll need a final finish for UV resistance but if you don't use cloth it will craze and check. I've seen it many times and it also sucks. It's easier than you think. You can do it. You'll be glad you did...

[dakippen]

Isn't it fun figuring out all these little details? And just as you figure out one another will pop up to take it's place! Enjoy the journey my builder friend...

I think you're on the right track. If I were to make a recommendation, I would go with 1/4" plywood with the mahogany veneer to get the look you want. Study up on some of the techniques on this forum for a sandwich style wall. Don't overbuild it. Two 1/4" pieces of plywood with a plywood skeleton between is a good choice. Foam inside the skeleton. I honestly think you could just sandwich foam and it would be fine. Just haven't personally done it but I've seen it done here. As far as the interior finish, spar varnish will look great. But on the outside don't skimp. You'll regret it. I've seen some failures and trust me you want to do it right the first time. A re-do sucks. Bad. And it's money down the crapper. Study up on epoxy. There's no substitute for a glass and epoxy exterior. I'm a coatings specialist and I wouldn't even think of just varnish or the like for a time honored finish. Go to youtube and check out some of the plank canoes and how they lay up the cloth and epoxy. As someone else already said you'll need a final finish for UV resistance but if you don't use cloth it will craze and check. I've seen it many times and it also sucks. It's easier than you think. You can do it. You'll be glad you did...

OH jeez - after reading this and doing what I did, I think I'm screwed now. I went with 1/8" plywood with the mahogany - I had it stuck in my head and not sure why but 1/8" would be okay (and my hubby keeps reminding me I was wrong). We have the panels cut, did the epoxy last wkend and it appears to have finally set up. The next step will be a finish with UV protection - I remember reading that was an absolute must. Hubby has no desire to add the glass and as of now, still can't convince him otherwise.

Here is my sandwich wall then - the exterior is the 1/8" mahogany, the 1/2" foam insulation, 1/4" birch plywood for the interior wall. The interior wall will be "wallpapered" with maps.

[Atomic77]

Don't worry yourself... I read where Noseoil suggested 1/8 ply. I said 1/4 only because that's what is available in my area. It's not a true 1/4, more like 3/16 to an 1/8. So I wouldn't get caught up in the manusha of it all. Your plan will work just fine I do believe.

Regarding the epoxy on it's on without the cloth... It's your build and your money. As a lot of projects go, (mine included trust me on that) you do it once, learn from your mistakes, then do it again the right way. Unfortunately, in circumstances such as these, that results in time wasted, money wasted and a lot of stress, usually. With that said, you might just get by with it. But from what I've seen, and I'm sure there are builders here that will speak up, you probably won't get by with it for long and will have to re-do it and epoxy ain't cheap! And if you think doing it the first time is hard, wait until you do it again and have to sand it all down. Sucky Suckerson. And that's putting it lightly. The cloth doesn't just add strength. There's something about the wood and the epoxy that just doesn't play nicely over time. And when I say time, I've seen it check, craze and crack in one season, so... yeah. But again, your time, money and labor. Not mine. Talk him into it. Get it built and do the exterior in one big shot not a panel at a time. Then you'll be happy for years to come. And make sure you sand the epoxy smooth before you top coat it or you won't be happy. Just don't sand through or you'll see it. I think someone already said get the cloth in a roll not folded because you'll see the fold lines, (I think it was this thread, not sure.) Anyway, good luck!

One more thing... I like your map idea! That will be cool. Maybe the side walls and not the end walls just to keep down the busy-ness? My 2 cents.

Study up on some youtube videos of cloth and epoxy over wood. Then make your case. Good luck!

[dakippen]

Don't worry yourself... I read where Noseoil suggested 1/8 ply. I said 1/4 only because that's what is available in my area. It's not a true 1/4, more like 3/16 to an 1/8. So I wouldn't get caught up in the manusha of it all. Your plan will work just fine I do believe.

Regarding the epoxy on it's on without the cloth... It's your build and your money. As a lot of projects go, (mine included trust me on that) you do it once, learn from your mistakes, then do it again the right way. Unfortunately, in circumstances such as these, that results in time wasted, money wasted and a lot of stress, usually. With that said, you might just get by with it. But from what I've seen, and I'm sure there are builders here that will speak up, you probably won't get by with it for long and will have to re-do it and epoxy ain't cheap! And if you think doing it the first time is hard, wait until you do it again and have to sand it all down. Sucky Suckerson. And that's putting it lightly. The cloth doesn't just add strength. There's something about the wood and the epoxy that just doesn't play nicely over time. And when I say time, I've seen it check, craze and crack in one season, so... yeah. But again, your time, money and labor. Not mine. Talk him into it. Get it built and do the exterior in one big shot not a panel at a time. Then you'll be happy for years to come. And make sure you sand the epoxy smooth before you top coat it or you won't be happy. Just don't sand through or you'll see it. I think someone already said get the cloth in a roll not folded because you'll see the fold lines, (I think it was this thread, not sure.) Anyway, good luck!

One more thing... I like your map idea! That will be cool. Maybe the side walls and not the end walls just to keep down the busy-ness? My 2 cents.

Study up on some youtube videos of cloth and epoxy over wood. Then make your case. Good luck!

I'll try and push the glass idea...I personally think it's a good idea, but men can be stubborn. The end walls are actually going to be pine tongue & groove....

[Atomic77]

For what it's worth...

https://youtu.be/MR06qBluKTc

https://youtu.be/EAa6gLYvgqE

[dakippen]

For what it's worth...

https://youtu.be/MR06qBluKTc

Thank you Mike for all your info - it's a real eye opener. IF (and I highly doubt it) I ever do this again, I would probably go with a foamie instead...

Just talked to the hubby - we used the West Penetrating Epoxy (A cpes type??) and then we'll use poly over that. He's concerned that if we add any more layering, my roof covering may not work. He was able to pick up some TPO for FREE which is great, but when it was cut, the cutter didn't allow for hardly any overlap. And since you shouldn't look a gift horse in the mouth....

[rruff]

OH jeez - after reading this and doing what I did, I think I'm screwed now. I went with 1/8" plywood with the mahogany - I had it stuck in my head and not sure why but 1/8" would be okay (and my hubby keeps reminding me I was wrong). We have the panels cut, did the epoxy last wkend and it appears to have finally set up. The next step will be a finish with UV protection - I remember reading that was an absolute must. Hubby has no desire to add the glass and as of now, still can't convince him otherwise.

I made a test piece with faces of the cheapest 1/8" luan, 1" 15 psi XPS foam, 48" long and 15" wide. I weigh 180 lbs, and if I support it on the ends I can jump up and down on it. It's *very* strong and stiff.

If it is glued well, 1/8 is plenty for both faces. I used PL Premium, troweled over the whole surface, and the foam was textured with a carpet seam roller. If you made any "mistakes" it was using 1/4" birch on the inside where 1/8 luan would have been fine.

How much did the exterior plywood cost? Just trying to get a gauge on the quality. If it's good marine ply it might be ok without glass, but glass is definitely better.

EDIT: Just saw that you used a CPES type product. I have no experience with it, but I know it's very expensive and supposed to penetrate, strengthen, and preserve wood quite well. It's possible that it will keep the ply from checking and deteriorating if you have a good UV coat. I think your best bet might be to go on the boat forums and see what they say.

[dakippen]

OH jeez - after reading this and doing what I did, I think I'm screwed now. I went with 1/8" plywood with the mahogany - I had it stuck in my head and not sure why but 1/8" would be okay (and my hubby keeps reminding me I was wrong). We have the panels cut, did the epoxy last wkend and it appears to have finally set up. The next step will be a finish with UV protection - I remember reading that was an absolute must. Hubby has no desire to add the glass and as of now, still can't convince him otherwise.

I made a test piece with faces of the cheapest 1/8" luan, 1" 15 psi XPS foam, 48" long and 15" wide. I weigh 180 lbs, and if I support it on the ends I can jump up and down on it. It's *very* strong and stiff.

If it is glued well, 1/8 is plenty for both faces. I used PL Premium, troweled over the whole surface, and the foam was textured with a carpet seam roller. If you made any "mistakes" it was using 1/4" birch on the inside where 1/8 luan would have been fine.

How much did the exterior plywood cost? Just trying to get a gauge on the quality. If it's good marine ply it might be ok without glass, but glass is definitely better.

EDIT: Just saw that you used a CPES type product. I have no experience with it, but I know it's very expensive and supposed to penetrate, strengthen, and preserve wood quite well. It's possible that it will keep the ply from checking and deteriorating if you have a good UV coat. I think your best bet might be to go on the boat forums and see what they say.

I didn't use marine grade, but it was still $70/sheet. Hubby had done some research on the CPES, we have a guy at work that highly recommended it, so that's what we ended up with.