Venting framing for Vaulted Ceiling
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Hi everyone,
I am planning a vaulted ceiling for my home addition and I like the ceiling assembly described recently in the June edition “A New Take on Insulating a Roof” which basically builds up the vent space with flat 2×4 fillers over the rafters.
However, the Canadian codes (NBC and Ontario at least) require 2-1/2″ of space between the insulation and underside of sheathing (clause 9.19.1.3). I assume the easiest way to build this is to put 2×3’s on edge on top of the rafters, instead of the 2×4’s on the flat?
Has anyone done this or do you think the 2×3’s on edge will split often when installing long structural screws?
Thanks, James
Replies
I wouldn't use 2x3. Impossible to find any of reasonable quality. Nailing through the narrow edge will likely split the 2x3.
You could build up the sleepers out of ply or OSB.
What long structural screws?
Yeah ply or OSB would could work... just a lot cuts and pieces to handle up to the roof.
For structural screws I was thinking of a ±4" GSS RSK or something by FastenMaster. Pre-drilling might help, and could be done on the ground at least.
Sorry, meant to say, what are the structural screws for? Other than the truss screws used instead of hurricane ties, I don't see any areas where regular nails are not sufficient.
Ah, I gotcha. I was just thinking structural screws over nails through the to possibly reduce the chance of splitting. Or perhaps could be regular screws?
You could still use 2 x 4s. Simply cut spacer 2 x 4s to raise the primary 2 x4 the required 2 1/2 inches (3" with this method). A 3" or 4" inch length spaced every foot.?? Pre-make on the ground. Faster than ripping up sheets of OSB and likely cheaper too.
I'd use 2x3s and 4 in. GRKs or Spax screws.
Thanks for the feedback! I am going to try drilling screws through the 2x3's (on the ground) and see if they split. If they do, then I really like the spacers as Suburbanguy suggested. It has the added benefit of some cross ventilation between bays as well... maybe not needed with a ridge vent, but I don't think it hurts. Agreed that it is likely cheaper (and certainly less work) than ripping OSB.
structural screws that can be used in place of lag screws to cut down on the time and effort put into drilling.