The Forestry Forum

Hi all - another beginner here.  Forgive me if I have some of terminology incorrect.

I'm building a 10x16 woodshed with a design that incorporates a king post trust supporting a ridge beam.  All posts and beams, etc... are 6"x6".  Rafters are 4"x6" cedar 4' oc with 7:12 slope.  Snow loads about 50 psi.  My plan is to use cedar shingles. 

What are my options for sheathing the roof?  I was thinking of having 2x4 purlins on 2' centers.  Purlins would be laid flat over the top of the rafters and would be covered with t/g 1x6 cedar.  The 1x6's would be covered with felt and cedar shingles.  I'm concerned flat 2x4 purlins would bow if they span 4' between rafters.

Alternatively, is there a type of sheathing or other boards you'd suggest I run perpendicular to the rafters and put the cedar shingles directly on top of, thereby eliminating the need for purlins?  I'd kind of like it to be all-cedar or at least nothing I have to maintain to any great degree while still looking nice.

Thank you for any help you could give.
Cheers.

I ran some of the numbers on the 2x4 at 2' oc spanning 4' and they failed.
I'd either move them closer together or make more rafters.

Hawth,

I recently designed a small pavillion that has three bents with king post trusses that carry a ridge beam.  The trusses are within the outside bent posts, and there are top-plates for both side walls.  I then used 4x6 common rafters 2 ft o.c. which rest on the ridge beam at the roof peak, and on the top-plates at the eaves.  This allows me to use 1x8 decking for the roof.

I would recommend using the 1x6 cedar, but allow a 1 1/2" spacing between the roof deck boards.  This will allow air movement behind the cedar shingle and give them a chance to dry out after it rains.  Many barns that were roofed with sawn cedar shingles have this spacing so that the roof would last longer and wouldn't need to be replaced as often.


Rooster

I'd go with Jim's suggestion of moving the 2x4s closer together and nail the shingles directly on them.
Are these store bought 2x4s and what length shingle are you planning on using?