Roof Problems

[TD_Dodger]

Hello TD_Dodger,

Sorry to hear that you are having problems. If my metric tape measure isn't lying to me, 2.7mm is close to 1/8". Cutting Kerfs into that thin a panel would be challenging and might not leave enough material to achieve any real strength.

It appears in your photograph that the grain is running the long direction of the sheet. I think if you were to turn the sheet 90 degrees from the way you are trying to install it, it will bend easier. If you do turn the panel, make sure your joints fall on flat surfaces and at a distance far enough from the radius that the is no ongoing stress in the joint(s). You may still need to use moisture or steam to achieve this radius.

On my build, the front radius is 20" and I used two layers of 1/8" Bender-board plywood. This material can be purchased at most better lumber yards and is available with the grain running either the long or short direction of the sheet, depending on your bending needs.

I know how frustrating these things can be. Somewhere in the replies you receive, you'll find a direction that makes sense for you.

Good Luck, Buff

im sorry but i got lost real quick. so the side i have showing on the picture should be on the inside of the tear drop? or the end thats by the galley should be in the front? im sorry but its been a long day so i got lost real quick. lol

[TD_Dodger]

It sounds like your trying to bend it too much without something backing up the outside. I'm not sure if I can explain this right but, from your pictures you are doing two things wrong for bending plywood with the grain in that direction.
1.. Your nails are few and far between, on the curve (and just before and after) you need to nail every couple of inches, not every 8".
2.. No straps, get a couple or a few straps that can be tightened as you nail. this will support the outside of the ply. You see, you have the sides supporting the inside while it bends, but nothing from keeping it from kicking out so it's going to break.
Once you do this, leave it for a few days to take the shape.
Lou

wow thanks alot. this makes sense i dont know why i didnt think of this duhhhhhhhhh simple simple simple lol

[doug hodder]

I don't know where you got your material....but watch some of the import plywood at the big box stores. The Chinese stuff has crap for a core, full of knots and voids and it will break exactly like yours has. At a speciality lumber yard, they will have better materials and last I checked, I was able to get 1/8" luan for like 9$ a sheet. Doug

[NathanL]

Is it real Luan "ply".

They sell this junk around here now with a luan face and back with a fiber core that has like glass strings running thru. It's almost like a minature hollow core dore. It won't bend at all without breaking.

[TD_Dodger]

Is it real Luan "ply".

They sell this junk around here now with a luan face and back with a fiber core that has like glass strings running thru. It's almost like a minature hollow core dore. It won't bend at all without breaking.

you know what now that you mention it im not to sure it is, this one has two different colors. on is darker than the other side.

[Gage]

you know what now that you mention it im not to sure it is, this one has two different colors. on is darker than the other side.

Where did you buy your luan?

[aggie79]

Like what everyone said, the BORG laun many times has a junk core. If you can find door skins at the BORG they are probably okay to use.

It is more expensive, but I used 3mm (1/8") Russian birch (similar to Baltic birch) and bent it around a 6" radius by hand with no pre-wetting, straps, etc.

[NathanL]

Is it real Luan "ply".

They sell this junk around here now with a luan face and back with a fiber core that has like glass strings running thru. It's almost like a minature hollow core dore. It won't bend at all without breaking.

you know what now that you mention it im not to sure it is, this one has two different colors. on is darker than the other side.

Yup. I used some to do the interior walls of my shop and it worked well for the purpose of just covering the insulating and wiring and it was super cheap. But like you mention it had two different types of faces and a core that was made more of peices and had a woven fiber cloth that snaked back and forth to hold it all together inside the core.

I'm not sure exactly what they call it. I got it from a local retailer and paid about $6/sheet and it actually looks pretty good once installed but has no structural strength at all but worked good for my purpose.

[LMarsh]

I found sometimes the sheets would bend well in the 8' direction, and other sheets would bend in the 4' direction. I guess it depends on the plys and the core.

The stuff I got from the box stores bent pretty well but I was doing a tight radius and no matter how much boiling water I used or what technique it would at least crack if not break once it reached a certain point. I used ratchet straps and a 2x4 under them, to even out the pressure, while pouring boiling water on it. The water didn't hurt it at all and did help.

I also tried bendable plywood. It was too thin and too flexible. It had no strength. Expensive too.

Finally at a lumber store I found some 1/8" luan that seemed to have one large inner ply core with the paper thing laminate on both sides. It bent great with no breaking or cracking, except it bent in the 4' length but I was making a 5' teardrop so it didn't matter.

[N6NG]

Ok... so now I'm confused.... Can you or can't you pour boiling water on luan to make it more pliable ? If you do put water on it one time for bending purposes will it ruin the luan once it has dried? I haven't got to that point yet but it's coming up soon so it caught my attention.

Dennis

[synaps3]

Ok... so now I'm confused.... Can you or can't you pour boiling water on luan to make it more pliable ? If you do put water on it one time for bending purposes will it ruin the luan once it has dried? I haven't got to that point yet but it's coming up soon so it caught my attention.

Dennis --

If you find a good grade of Luan, it shouldn't matter.

I wouldn't attempt it with Luan from Lowes, etc otherwise you might get delamination.

I am also speaking from the experience of others... On my build, I plan on cutting kerfs and avoiding water at all costs before I seal the wood. No sense risking it!

- Dave