5x9 Hybrid

[TJinPgh]

As an aside to that, I would be curious to see if anybody had ever done any tests on whether or not a curved roof is any less prone to sagging than a flat one.

It's been my experience that structural panels rarely flex in both directions at the same time. At least, not on their own.

Might well be possible to go thinner on a roof with a curve.

[GPW]

The curve is stronger, much as corrugated tin is stronger than a flat sheet ... an arch stronger than a box ... old technology ...

[atahoekid]

Wish I had thought of that during my build. I had to work pretty hard to make sure my flat roof didn't sag (2" foam, 7 feet wide). I ended up putting 1 x 3's on the flat to prevent the sag. A little arch in the roof would probably have made the added support unnecessary but probably would have made the seam between the nose and the roofline harder to manage

[TJinPgh]

Well, unfortunately, anything bigger than a 4x8 with a flat roof is going to have a seam in the roof somewhere unless you're skinning with aluminum or something that you can get in a wider width.

[GPW]

TJ, Not to Worry !!! A seam is just another place for a “reinforcing strip” ... Got 2 seams in my roof ... no problems !!!

[KCStudly]

Oh the power of the mighty arch....... and GG to stick the foam together.

TPCE, as many of you know, has a gentle arch throughout the whole roof lengthwise. 5ft wide (flat from side to side...well, 64 inch really) with integral spars buried in the foam at the roof vent, and structural support from the cabinet face frames underneath front and rear. I don't expect any problems... but who knows, "ain't got there yet".

[atahoekid]

Oh the power of the mighty arch....... and GG to stick the foam together.

TPCE, as many of you know, has a gentle arch throughout the whole roof lengthwise. 5ft wide (flat from side to side...well, 64 inch really) with integral spars buried in the foam at the roof vent, and structural support from the cabinet face frames underneath front and rear. I don't expect any problems... but who knows, "ain't got there yet".

Well, I hope you don't have any problems cuz that's how I planned and built my roof (without the arch). So far, I am amazed by the structural strength. I think you'll find your foamie amazingly rigid.

[Wobbly Wheels]

I took the arch out of my roof, mostly because it looked awful. The center section was about 4X6 and had a healthy curve across its width - about 3" higher in the center. I won't be walking around up there so I opted for the easier glassing of a flat panel.
I have an array of four 15W solar panels to go up there, but they will be mounted flat on glassed foam rails that carry the loading out to the side walls.

That said, I'm also using glass rather than canvas so potential seam problems aren't an issue.