||03-13-2013 10:47 AM
How to (safely) a cut a ceiling joist
I have a 1971 single-story ranch house with a hip roof. Last fall, when I had it re-roofed, I had the roofers install a 20"x20" roof jack for a downdraft swamp cooler. It's in the middle of a 24" O.C. rafter bay.
Below the cooler, I have 16" O.C. ceiling joists, and of course one of those joists is directly below the swamp cooler so it will need to be cut to allow the duct to come down.
I know it's odd, but there is no truss in this area (near a hip). My HVAC guy who will be doing the ducting recommends just cutting a 20" section out of the offending ceiling joist, but I think it needs reinforcement. Should I simply head off the cut joist by installing perpendicular blocking between the neighboring joists, or should I run two new joists 24" O.C adjacent to the duct opening and parallel to the existing joists?
Also, do I dare use a recip saw to cut the joist? Since this is 1971 construction, the drywall ceiling might be nailed up instead of screwed, and I'd hate to pop nail heads all over my ceiling or crack a taped seam (some of the taped seams are already iffy)...