Roof Ridge Sag

I have a two story home that is 120 Yrs old. The roof ridge has sagged about 6". The rafters are about 36" on center with full size 2x4, 2x6 ridge board and 1x8 collars. The knee walls are both leaning in the same direction. The building is 24' wide and the rafters will span 9 and a half foot to the ridge board, the room is 16'. I am planning on jacking the roof by nailing a 2x6 just under the ridge attaching the top of both rafters covering the three center rafters at a time. Lay a 4x4 under the short collars beneath the ridge and another 4x4 from the jack lifting it about a quarter to half inch a day. If it comes back then support the kneewalls and put a wall back in.
Will this work or can you give me a better idea of what to do ?
Thank You
micki

 

I would probably do something along those lines myself. With those old homes a sagging roof may go all the way to the foundation. Be ready to switch plans in the middle of the project of necessary. Good Luck

 

Jack the Contractor, What am I looking for to happen if it goes to the foundation and then do what ?
Thank You

 

Look at the outside walls there at the plate line . You might want to pull them in at the same time as you jack up the ridge beam.


ED

 

Micki:

With years of experience in sagging ridge beams, I have found that there are usually only a couple of causes. If a rafter or truss is not broke, then usually it is some structural problem other then the roof. However in your case, with 36" rafter spacing and only 2x4 rafters, it is possible that some of them have sprung, or kicked out. However if you find this is not the case, then you will have a structure problem on one of the lower floors or foundation. Now, if you cannot get the ridge up by your methods, then the next best thing would be to re-roof your ridge and build it up level from the outside, then reshingle.\
Good Luck