I’m going to build a covered porch on my house. My plan is to use 4″x6″ western red cedar for the roof rafters on 24″ centers. Then my plan was to use 1 x 6 T&G western red cedar for the roof sheathing. I was concerned that the 1 x 6 would not be strong enough on 24″ centers so I also planned to put 1/2″ CDX plywood on top of the 1 x 6 and then shingles. My question is will I have a problem with seasonal movement of the solid cedar 1 x 6 and the plywood nailed to the top of it which will have very little if any seasonal movement? Any advice would be greatly appreciated. Thank you.
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On the surface, I think if you use adhesive like PL premium between the two, you'll have no problem.
But since you say nothing about your climate zone and live loads required for your roof locally, I can't comment with any sort of accuracy
Do not glue the CDX to the cedar boards. As you said, solid wood will move, plywood won't, somethings got to give and it will be the cedar in the form of cracking. The CDX is a good idea primarily for nail length. I guess you don't want nails sticking through the cedar. Watch out when nailing drip edge, flashings, starter courses, paper. Nails that don't protrude on layers of shingles might with thin materials.
I use the glue precisely to stop it from moving independent of each other
What's the span on your 4x6?
I would use 2x doug fir for your rafters 16" o.c. then use 5/4 x 4" TK cedar decking for your sheathing.
It will cost less and look great from the under side.
forget using plywood on top of the sheathing.
Glad to see you back!
That is a real nice looking roof!
Yoo Hoo Eugene!
So where are you located man?
Located in Northern ILL, about 100 miles west of Chicago and 15 miles south of Wisconsin state line. Want to thank everyone for all the advice given.
That is an area where you need to consider snow loads. I don't have tables for WRC structural but I don't think you would want to span more than about 8' with that layout