Roof Question

[Fiferguy]

I apologize in advance if this question has been asked before, but I searched for about a half hour and I couldn't find it.

How much does the roof sheeting contribute to the structural integrity of the TD? Or does the majority of it come from the roof spars?

Right now, I'm planning on using 2x2s for my roof spars with 1.5" foam insulation. On the inside, I'm going to use 1/8" wood sheeting, but I'm trying to decide if the outside truly needs 1/4" sheeting, or if 1/8" will suffice. I'm planning on sealing and painting the entire exterior of the TD, and probably painting the inside as well.

So I guess my question is this: using the idea above, is 1/8" exterior sheeting enough, or does it really need to be 1/4"?

Thanks in advance! And if this has already been answered, if you can point me in the right way I'd really appreciate it.

[Wolfgang92025]

For what its worth, I used 1/8" ply inside and outside for my roof and its plenty strong.

[danlott]

The plywood adds the majority of the strength, but it is both the plywood and spars that work together to provide the strength. 1/8 inch plywood on the interior should be fine. If you are covering the exterior with aluminium then 1/8 inch plywood should be fine, but if you are only sealing and painting then I would use 2 layers of 1/8 inch plywood.

Dan

[jonw]

If you're covering the roof with aluminum you dont need to have plywood underneath it except at the hatch.

[markhusbands]

If you're covering the roof with aluminum you dont need to have plywood underneath it except at the hatch.

It seems like that'd be true IF you use .04 and IF you make sure there are no flat spots. And avoid putting anything heavy on the roof.

[Jdw2717]

I used 1/8" birch on top and 1/8" birch for the inside roof with 1.5" x 1.5" stringers and foam insulation. It works great and is really stiff. Also used oil based primer and latex exterior paint (mine lives in the garage when not in use) for the exterior and latex paint inside.

[Fiferguy]

Thanks for the replies. I just wondered if this was another one of those places that we tend to over-engineer everything. It doesn't seem to me like the roof will be supporting any significant weight, other than the wind when travelling and weather. The only thing I plan on putting in the roof is wiring and a vent w/ a fan. It seems to me that with enough spars that it wouldn't be an issue--I'm planning on 12 inch centers on the flats and 8 inch or 6 inch centers on the curves. Depends on what it looks like when I start to build, and where I need to join sheets together.

[Tinbasher]

I think the double skin might create a " torsion box" adding more strength than you might think.

[Fiferguy]

I think the double skin might create a " torsion box" adding more strength than you might think.

That's exactly what I was thinking--similar to a wing on an airplane.

[desertmoose]

Mine has a roof made of (from the inside out) 1/8 hardboard paneling, 1-1/2" polyurethane insulation between the spars, 1/8 tempered one side hardboard (masonite) with canvas/ paint on top for weatherproofing.

I actually have sat on it while installing the vent. It's a lot stronger than you'd think.

A year and a half now, without any problems or concerns.

Sam

[woodywrkng]

I used spars of 1 x 1 1/2 poplar, spaced every nine inches, with 1/8 plywood inside and out. .040 aluminum for the roof. When I attached the outside plywood, as well as the aluminum, I used two cast iron Ford cylinder heads and three 40 pound bags of kitty litter to hold everything flat. The roof wasn't affected at all.

[citylights]

I used spars of 1 x 1 1/2 poplar, spaced every nine inches, with 1/8 plywood inside and out. .040 aluminum for the roof. When I attached the outside plywood, as well as the aluminum, I used two cast iron Ford cylinder heads and three 40 pound bags of kitty litter to hold everything flat. The roof wasn't affected at all.

In a pinch, you could use that roof as a CAR hauler! Holy, 9-inch on center... And I thought mine was overbuilt.

I used all the same except 2x2 spars at about 18 inch o.c. And I haven't got the aluminum skin on yet. And I will be putting a roof rack on mine to park kayaks on top.

[Fiferguy]

I should also say that I don't really like the look of the aluminum skins (not that the trailers look bad, just don't want it for mine), so I won't be skinning it at all. This is going to be mostly a wood build, with some foam, plexiglass, and glue thrown in there just for fun, and covered in a few coats of paint.

[citylights]

I should also say that I don't really like the look of the aluminum skins (not that the trailers look bad, just don't want it for mine), so I won't be skinning it at all. This is going to be mostly a wood build, with some foam, plexiglass, and glue thrown in there just for fun, and covered in a few coats of paint.

With no aluminum skin, I would be worried about puncture on a 1/8th skin. A rambunctious teenager could put an elbow through that, one wrong move with a fishing pole, one errant tree branch...

[desertmoose]

I should also say that I don't really like the look of the aluminum skins (not that the trailers look bad, just don't want it for mine), so I won't be skinning it at all. This is going to be mostly a wood build, with some foam, plexiglass, and glue thrown in there just for fun, and covered in a few coats of paint.

if you're wanting a painted finish, consider putting canvas down first. We really like how ours turned out. All edges are completely sealed, and the canvas give a great surface for the paint.

Take a look at our build journal and photobucket account for pictures.

Sam