The house is constructed with 2×4 trusses, 24 inch on center. The trusses span an open area 27 ft long with no support in between so the ceiling is sagged in the middle and the roof ridge is sagged as well.
I jacked up the ceiling to where it should be and installed (2) 2×10’s on each side of the center truss supports in the attic. However, after removing jacks the ceiling came back down almost to where it was previously.
The 2×10’s are approx. 18 ft long with end support only since I don’t want to have a post in the middle of my living room.
My question is:
Will adding more 2×10’s to the 4 existing help and if so how many in total would be required ? Or is there a better solution ? Thank you
Best Answer
This is very common for older stick framed homes that were not engineered and the code very minimal. The reason is obvious, it is not constructed strong enough
What you did with the 2x10's is called 'sistering' or 'sistered.' The way that you did it does not add strength to the roof structure as a whole, as you have learned.
Answered directly and simply
Yes
Answered more fully aka 'How' or 'What' is a better solution
It's complicated. It depends on the particulars of your roof framing, the wall layout of your home, and other issues. It involves not just the old framing member sizes, locations, wood species etc, it also includes the connections of the members and other things like constructability issues (how to get members into place at minimal cost)
Generally this is a project for a structural engineer. I'm guessing that you may note like that idea, for reasons. But there is no answers to be found here, from friends, and probably not from contractors, it's simply too complicated an issue.
There is ONE option that might be plausible for your situation: you can make the ridge into a post and beam system. This reduces the rafter spans in half. You'd need a beam of course, and posts, and footings (the existing foundation also surely not able to take these new point loads)