I have a post frame building that was recently constructed where the post and joists have 8 foot on center spacing. The building is 38' x 54' and we had a 2nd floor built on the North end of it which measures 38' x 30. This 2nd floor is to be a framed in and finished "living space". I didn't consider how I was supposed to do a drywall ceiling on the 2nd floor when the trusses are so far apart.
I was considering using 1×3" 16' furring strips to span over 2 trusses at 16" on center. I'm afraid that an 8' span will still sag with drywall on it.
My other idea was to put 2×4 8', 16" on center, in between the joists with hangers like these
Would either of these ideas work with what I have? Are there better options?
Best Answer
Assuming you go with the idea of hanging 2x4 ceiling joists, you might consider using a top-mount hanger.
This would take advantage of the fact that the truss members are also a standard 2x size to save time; top-mount hangers would "automatically" be square and located in the correct vertical position.
Example: Simpson HU26TF for 2x6s.
(You could use a 2x6 hanger for 2x4 joists)
Having recently installed scores of the regular kind I think you would appreciate the time savings.
That said, I'm not sure if your truss loading specifications are for bottom-mounted loads? E.g., something like snow load obviously assumes the truss is loaded from the top. So I would double check that detail.EDIT: Ecnerwal commented that the BCDL=8 PSF is the load rating applicable here.
A sheet of drywall which is 32 sqft weighs around 50 lbs plus you'd need 3 2x4s per sheet, each at ~10 lbs. So the total = 80 lbs / 32 sqft = 2.5 PSF.
So assuming that 8 PSF is accurate you should be well clear.
Final thought - the trusses should be spaced evenly, but might bow a bit in the middle. Before you cut all your joist material I would measure each bay at both ends and look for any irregularities. I never assume anything wood is actually rectangular or consistent.