How thick should the roof be?

[Arne]

I see aluminum as a finished surface, not adding much strength to a tear.

[cracker39]

Where have you found 1/8" luan or birch? The thinnest I have found at HD or Lowes is 1/4" or 5.2mm. I'd rather use two 1/8" if I can get it for the exterior top skin. For my exterior front and back, which are flat pieces, I'll use the 1/4". That will go on the top as well if I can't get the 1/8". I found "sanderply", an inported 5.2mm hardwood plywood, and moisture resistant Luan in 1/4". I'm leaning toward the luan. Anyone have experience with the moisture restant variety? I will finish in a spar varnish sealer, then white enamel or epoxy finish.

I found nice light oak finished panelling for the interior that is about 1/8" thick. There is also plain white paneling that I may use for the ceiling. Either look like it will bend easily. The RV door I am buyng is smooth Polar White on the exterior to match.

[TomS]

Where have you found 1/8" luan or birch?

You can get 1/8 birch from Boulter Plywood in Sommerville, Mass. I've had very good results with their 1/8 bending birch and 3/8 Wacky Wood (2-ply luan). Depending on what you buy, they can roll it up and ship it to you.

[Arne]

I checked 'lumber yerds' in the yellow pages and called around. found a place about 15 miles from me that stocks mahogany..... in 1/8.

[Gage]

BTW you dont need alloy for that strength, I walked up and down on a pce of birch ply with insulation behind, no damage, I had to jump and slam heals on to surface to break, a thin layer of alloy would not help.

Well, beings how your so set on your way of construction and you like to test. Why don't you build a mock Teardrop. Make the sides out of 1/2" ply and probably only needs to be 3 feet high. Then spread them 4 feet and at least 6 feet long, apply a roof like you say and then get up on it and jump up and down in the middle. Then come back and let us know the results. I would like to know. Mater of fact, all would probably like to know.

Thanks for that 200 lb. roof comment Gage. I'm not planning to stand on it but who knows what some neighborhood kid will do.

Toolie, it wasn't planned. One morning at a gathering, my wife and a friend noticed that the Ezup over the tear had come apart in the wind. So our friend just climbed up on the tear and fix'd the Ezup. It happened again later in the day, so I just climbed up on the tear and fix'd it. I don't use that Ezup anymore.

Have a good day.

[cracker39]

Hmmmm...why didn't I think of that. I made some calls and found only one dealer that stocks 1/8" ply about 18 miles away and it's birch at $20.71 per sheet. I'd need 5 sheets to do my top in two plies. That's about $112 with tax. If I do it in 1/4" luan, it will only take 3 sheets and cost me about $44. I don't have a major curve on the roof, just the one sharper bend in the front to cover and the 1/4" should bend around that one. I can't see spending over twice as much for birch when the plywood will be painted. I bounced a boat around a lot and dragged in up on rocks on the beach and didn't even scratch the 1/4" luan I made it out of.

[cracker39]

I certainly hope I don't have to get onto the roof of mine for any reason. I did a lot of standing in a boat I constructed from one thickness of 1/4" luan plywood, but that's a different situation. The boat bottom was on the water, so there was resistance (water) under the floor to counteract the weight (me) on top of it. The plywood did ripple some when running it with an outboard over choppy water, but never flexed or twisted horrizontally or vertically along the bottom or sides. I built that boat because I couldn't buy one like I wanted. It was only 12' long, but nearly 4' wide across the bottom for stability. Just like TD owners, I had other fishermen and even a game warden look at it and ask "Did you build that?". Yep, it made my day.

yeah, I know, I'm always putting in my $.02 worth...sorry about that.

[GeorgeTelford]

Hi Gage

I'll most likely do something like a weekender, so its unlikely that I'll get to test (framing etc) in a tear as such.

But I will say that intelect and experience tells me that with decent framing and solid foam insulation in between the spars there will be no problem. Also having worked with thin aluminium sheet for years I know its not really adding any great strength. Also if you get a ding insheet ply due to stone etc it will be simple to repair and refinish, if an alloy sheet tear gets a ding, the repair will be a major job of work and the cost.........

In caravans and motorhomes 1/4" ply is used as the bed board with no spars or insulation as support and I have never seen one broken yet.

I used 1/2" in a motorhome I put togethor and was then shown what the pro's use 1/4" looks way to flimsy, but it works.

[GeorgeTelford]

Hi Cracker

Thanks for that 1/4" luan is not as tough as beech and your boat story further supports what Mike and I found, that ply alone would be strong enough for a tear roof. Water would not be as good a support base as spars and insulation

I missed your posts while writing my last.

[cracker39]

George, my boat had spruce framing, mostly 3/4" x 1 1/2". I think the bottom cross spars may have been a little wider, maybe 2". The cross spars were about 24 " apart. Then, I had a 3/4" x 3 1/2" keel running along the center of the bottom (underside), so the ply was well braced. The point was that down it's length, you'd think it would twist some, but it didn't. Several pieces of plywood (i.e. boat sides and bottom or sides and top as in the case of a trailer) joined around a frame are plenty sturdy. I don't believe that a trailer with inner (1/8") and outer (1/4) plywood skins on a spruce or hardwood frame will bend or twist. And, although I wouldn't want to stand on it's top, I think it would support my weight with no problems.

[Gage]

Hi Gage
I'll most likely do something like a weekender, so its unlikely that I'll get to test (framing etc) in a tear as such.
But I will say that intelect and experience tells me that with decent framing and solid foam insulation in between the spars there will be no problem. Also having worked with thin aluminium sheet for years I know its not really adding any great strength. Also if you get a ding insheet ply due to stone etc it will be simple to repair and refinish, if an alloy sheet tear gets a ding, the repair will be a major job of work and the cost.........
In caravans and motorhomes 1/4" ply is used as the bed board with no spars or insulation as support and I have never seen one broken yet.
I used 1/2" in a motorhome I put togethor and was then shown what the pro's use 1/4" looks way to flimsy, but it works.

Excuse me, but arn't we suppose to be talking about a Generic Benroy with a single sheet of 1/8" (and spars). Now you come back to me with installation added and I assume you plan on covering the installation with another piece of 1/8". So tell me, how thick is that going to be? The way I read your post, your saying the same thing that I've been saying. I need to go back and read that again. "But I will say that intelect and experience tells me that with decent framing and solid foam insulation in between the spars there will be no problem." Yep, that's what you said.

Have a good day.

[GeorgeTelford]

Hi Gage

Yes we were discussing that and as far as I can see nothing as changed

Looking at the drawing in the generic thread shown below it looks like there will be spars and insulation in between, this thread was discussing using a single sheet on the outside and would it be strong enough?



After we (Mike and I) experimented, Mike decided that a single layer would work ok

and I quote

My recomendation as I posted in the generic build thread today was either 1 layer of baltic birch or two layers of luan. (All 1/8" of course). This is designed to be painted....

I just needed a rock solid option for the generic build...

no-one actually dissed your method Mike even gives you an honourable mention

There are other options of course... such as the way Gage did it, or the way Steve did it.

I have never been against your method, the only reason I mentioned it at all was that it had little/nothing to do with the original question.

Would you like to have a wager on whethor I am right or not?

[mikeschn]

Okay, I think we can put this to rest now...

We have a recommendation, and I even have drawings... I thank everyone that helped come up with the answer.

Mike...

[cracker39]

Mike, I've made up my mind...don't confuse me with facts!!!



(of course, my mind is unstable and subject to severe changes)

[Gage]

Aw man Mike, I just got the other post (from the other thread) and your start post of this thread copied and ready to throw it out plus a finial statement..... I wonder where I can go now and have more fun beings how I can't work for a while. That's another story. ( starting to sound like Shrug)

I'm out of here, have a good day.