We recently had our home reroofed with asphalt shingles (40 yr Certainteed) The roofers added 1/2 in. plywood over our existing plank decking.
Our living room is a large open room with a fireplace in the center of the room. In the attic, the area above the living room has 18 foot 2 X 6 rafters spaced 16 in or so apart that do not have any supports running down to the ceiling joists. I believe this is because there are not any load bearing walls to support this. The rest of the house does have supports running down to the ceiling joists.
We have noticed that the roof above the living room has a slight sag, probably not noticeable to anyone but ourselves. Here's my question...
a) will the sag worsen?
b) are there any ways to strengthen the rafters and eliminate the sag?