Another plywood question

[TPMcGinty]

I have read where people have used either one or two layers of 1/8 inch bending plywood for covering the roof. Is using two layers of 1/8" bending plywood better or easier than using one layer of 1/4" bending plywood? Thanks for your time.

[H@nk]

I know it exactly to say in Dutch, but in your language its a little more dificult.
The workebylity is like a beercan and a fender. Is that clear enough?
So the .25 is harder to bend than the .125

[doug hodder]

That's what I did on the front end of the American Tear...2 layers of 1/8" baltic birch give a nice smooth curve and plenty of strength. It's not the bendy ply, just plain 1/8". All exterior roof materials are Baltic Birch on this one. It takes on epoxy much better than lots of other plys. I've used the Home Depot "chi-ply" 1/4" on previous builds...bad decision...the core caused it to explode and made for a lot of body work to hide the crack, and the curve was on a trailer for 2 profile. Just what I've experienced. Doug

[Sam I am]

Ditto what Doug said about the 1/8" Baltic birch. It literally falls around the curves of its own weight! Good for the hatch, since it puts almost no "unbending" force on the hatch framing, thus eliminating the dreaded springback problem that many have encountered with thicker materials! I used two layers of 1/8". One would probably have been strong enough, but two gives it some puncture resistance against flying road debris, etc.
Sam

[madjack]

...first off, when using "bendy" ply...bending 1/4 is not much harder than bending 1/8th...I have bent both to a 4" radius with very little problem...secondly, "bendy" ply has a tendency to want to sag if run flat on a vetical plane...(it is very strong in the bend)...we hadda put our ribs/spars on 8" centers to eleiminate this sag and third, "bendy" ply has a very open grain and will soak up a lotta epoxy/urethane or whatever you use to seal it...FYI...we were using 1/4" "bendy" ply (mainly 'cause we couldn't find 1/8th)...
madjack

p.s. if you are going to skin in AL, then the 1/8th would be sufficient...if goin' "woody" you should consider two layers......MJ

[TPMcGinty]

...first off, when using "bendy" ply...bending 1/4 is not much harder than bending 1/8th...I have bent both to a 4" radius with very little problem...secondly, "bendy" ply has a tendency to want to sag if run flat on a vetical plane...(it is very strong in the bend)...we hadda put our ribs/spars on 8" centers to eleiminate this sag and third, "bendy" ply has a very open grain and will soak up a lotta epoxy/urethane or whatever you use to seal it...FYI...we were using 1/4" "bendy" ply (mainly 'cause we couldn't find 1/8th)...
madjack

p.s. if you are going to skin in AL, then the 1/8th would be sufficient...if goin' "woody" you should consider two layers......MJ

Thanks everyone for your input. Madjack your statement about the tendency of bendy plywood to sag makes me wonder if I should only use the bendy stuff on the bends and the regular stuff on the flat areas.

[madjack]

Tim, we were using 1/4" bendy ply with ribs set on 12" centers...on the flat sections you could see(barely) a sag between the ribs...we decreased the distance between the ribs(to 8.5"s) and the sag went away and we have never seen it return...cost wise, it would be more effective to use regular ply on the flats and the bendy on the curves, but it will work just fine on the flats with the closer spacing on the ribs.....
madjack

[Isalvus]

Tim,
I skinned the entire outside of mine with bend-a-board and just recently decided to do the interior roof with it. I used 3/8" and most places that have the 1/8" or 1/4" should also have the 3/8" (they even make in in 3/4" but its a different animal). Anyway, 3/8 bends just as easily as the others and you only need the one layer and it wouldn't have that sag that madjack found. I found mine for either $25 a sheet or $31 and it is worth every penny. Trust me, it'll make your life a lot easier. Kevin

[TPMcGinty]

Tim,
I skinned the entire outside of mine with bend-a-board and just recently decided to do the interior roof with it. I used 3/8" and most places that have the 1/8" or 1/4" should also have the 3/8" (they even make in in 3/4" but its a different animal). Anyway, 3/8 bends just as easily as the others and you only need the one layer and it wouldn't have that sag that madjack found. I found mine for either $25 a sheet or $31 and it is worth every penny. Trust me, it'll make your life a lot easier. Kevin

Where did you get your bend-a-board? Thanks.

[Isalvus]

I'm near the port of Tampa, FL and there's a place here that wholesales it. They get it directly from overseas and their prices are great, but even at a hardwood place they sell it for about $30. Cabinet making supply shops and boat builders are the biggest users of it, so I would start your search there.

[Isalvus]

oh and FYI there are two types: barrel or column. Barrel bends on the short side (forming a barrel, obviously) or column, bending on the 8 foot side (making a column). My trailer is 62" wide so I bought column every time

[TPMcGinty]

I'm near the port of Tampa, FL and there's a place here that wholesales it. They get it directly from overseas and their prices are great, but even at a hardwood place they sell it for about $30. Cabinet making supply shops and boat builders are the biggest users of it, so I would start your search there.

Darn! Tampa is a little far away from me and probably much warmer. I have looked around hear and the best I can find locally is 1/2". Thanks for your help. I will keep looking.

[TPMcGinty]

oh and FYI there are two types: barrel or column. Barrel bends on the short side (forming a barrel, obviously) or column, bending on the 8 foot side (making a column). My trailer is 62" wide so I bought column every time

Thanks! I had already planned to get the column type since my tear is going to be 5' wide but keep putting out that kind of information. It's nice to know that there are people out there willing to give me their time and experience. Have a great day!

[Senior Ninja]

You might like to check out my method for bending quarter inch plywood in the General Discussion, "Steve's Trailer." I had no problem bending plywood. Strangely that is the number one question I get whenever I take the trailer out for camping. "Say, how did you bend that plywood w/o breakinking it?" A lot of very hot water, a beach towel to hold the heat on the wood and patience worked for me every time.
Steve