roof spar size

[adlibdrama]

How big do the roof spars need to be? I was thinking 3/4x1. Is that going to be strong enough? It will have a layer of 1/8 ply inside and out and the voids filled with XPS. I don't plan on climbing around on the top of the thing, but would like to keep my options open for adding a boat/bike/cargo rack to the roof later on.

Dennis

[mikeschn]

I typically suggest using 1x2's which actually measure 3/4" x 1 1/2".

Look at the generic benroy plans up there in the menu. You'll see my spar recommendations, as well as the build direction.

Mike...

[prohandyman]

I use pine 2 x 2's, especially if I was planning on a roof rack of any kind. And maybe even 2 x 2 spacer between the spars along the top of the walls for additional support! You might be safe with something smaller if your rack attached to the sides, if your sides were something like 3/4 ply, then the rack would provide support. IMHO

[Ageless]

Agreed; use the sidewalls to support a rack.

[bobhenry]

I use pine 2 x 2's, especially if I was planning on a roof rack of any kind. And maybe even 2 x 2 spacer between the spars along the top of the walls for additional support! You might be safe with something smaller if your rack attached to the sides, if your sides were something like 3/4 ply, then the rack would provide support. IMHO

I'm with dan I cut the 2x2 spars ( 1 1/2" x 1 1/2 ") out of #1 southern yellow pine 2x10's or 2x12's. The southern yellow pine is about 50% stronger than the spruce pine fir and being #1 grade there are fewer knots to weaken the member.

I am sure being in Canada the idea of a bit more insulation room is not a bad thing either.

As to the roof rack plan now My 2x2's become a 2x4 at the hatch where it is carrying more load, I installed a handicap rail in Chubby to help in moving around in the tear ( and very glad I did ) I actually placed 3 spars side by side by side and screwed and glued them to act as one before attaching the rail.



I would plan for the rack in advance and reinforce where needed. There is nothing in the world more sickening than the muffeled crack of bones trapped in the layers of your finished tear.

[boomboomtulum]

Another who used 2x2's. Consider the space gained to glue, screw and attach things to like cabinets int. and ex. plywood. The extra strength through the 2x2 is not a huge extra weight but if you plan on some external racks even attached tho the sides, that is how I would go.
Dave

[Mike Angeles]

I used 2 1x2's of Poplar, glued together with apposing grain for strength.

Mike