So here’s the background story: The house was built in 1975, and the garage has its own trusses not common to the living space. The drywall ceiling started to come loose, with one sheet hitting the floor. But missed the cats.
The drywall was originally nailed in place directly to the trusses, and 45 years of uninsulated expansion and contraction has taken its toll.
At this time 2/3 of the drywall ceiling has been removed, furring strips are being installed perpendicular to the trusses with coated wood screws, and wainscoting is being installed and completed with the first 8’ x 20’ section.
The sagging problem was discovered when installing the second run of furring strips. Trusses are 2”x4” pine with old style round hole truss plates at the joints. The trusses run in the 20’ measurement, and at 14’ there is a splice that is sagging. Above the splice is a 1’ long board across the splice.
Correction: the trusses run in the 24’ measurement.
Researching on how to repair I have come across multiple methods. One is to bolt 1/2” x 4” angle, four foot long on either side of the splice attached with bolts. Second method is 2”x4” board four foot long attached on either side with either screws or bolts every 6 inches, and banded in four places along the brace.
There are eight trusses that need strengthened, which will require leapfrogging with two jacks to bring the splices back in alignment. Two others were installed 180 out from the rest, and those splices are already covered by new ceiling.
My concern is the horizontal drilling of the existing trusses as nowhere have I found what diameter screws or bolts to use. I do not want to weaken the existing truss by drilling/removing wood.
So has anyone here had the experience of mitigating sagging trusses?