Kenton made a good point. My reply was geared toward the probable cause and did not address any possible solutions.
Without seeing the entire attic and support framework I cannot suggest a fix for your problem over the internet. If the problem is related to the issues I listed there will be no cheap solution. Long term sagging of lumber also involves plastic deformation of the wood fibers which cannot be totally reversed.
Sistering on both sides of an already over spanned rafter only adds more dead load to an overloaded rafter. Ideally you probably will need some additional support at mid-span of the sagged rafters. There are a few ways of doing that but each method is customized bases upon your framing situation and interior wall support locations. Sagging over large span areas like a garage may require a support beam in the attic to support the ceiling joist and any diagonal braces installed to support the rafters.
My main point is you need to identify the root cause of the problem before you spend money trying to fix the symptom.
Sistering the whole length, from plate to ridge or wall to wall is the only way to do it without adding additional dead load to the sagged or damaged rafter. The only problem with that is the constructibility issues with getting a 16-foot or longer 2x6 into the attic and into place. In a case like this you will have to jack the bowed rafter back to it’s original position in order to get the new rafter in place. Then with a considerable amount of sweat, sledge hammers and hydraulic jacks you may get it in. All to often the contractor or more likely the homeowner’s brother-in-law takes a short cut and trims the end of the new rafter to make the installation easier which now no longer transfers the loads properly. On the plus side this particular house has what appears to be a fairly large attic area so there may be some room to work.
From the picture the ridge line has sagged which indicates the fix will involve multiple rafters and a significant amount of work. If you leave the ridge line “as is” any new full length rafter will be slightly shorter than the original. Jacking up the ridge line will cause the existing sagged rafters to pull away from the ridge board. Working in a confined space is very time consuming and any contractor who has been in the business for a few years has learned this the hard way. So in order to recoup his labor costs the bids will be high enough to make the home owner sit down and think twice about tackling this project. Again without actually looking at this house I am only guessing on the extent of the problem.
I see upper and lower cord with no bracing. It might help to if you add gussets cord intersections to brace it all together.
Here is a photo.
Also Mr.Mayo they can bring even thing in through the gable end vents. If non make a hole at both ends to add ventilation if needed if not close it up after.
If you use jacks to straighten out the work many factors have to be taken into considerations.
You will be applying forces to the ceiling components ( joists, wall framing, plaster ) and you must set up jigs to compensate for the loads.
Also jig ( 8 foot ) to be seated and cup in place that rafter you single out to straighten. Then sister it in place, and gusset all cords together.
Its tricky as you mention.
Mr Hetzel.
Cambers often form with the use of logs being handled wrong at the mill also. BUT
When trees grow on mountain sides, scientist have noted that those are the timbers that tend to curve during humid days, freezing conditions and fluctuations in temperature and weather drying out or lack of humidity,etc.
The word camber.
Sheeting looks inadequate also to K.
I see several variables at work in that photo.
You have inside photos of that home Kenton so we may see the interior rafter design ?
Hello,
We have finished framing our 20x30’ building. We have 10’ walls and one single lam beam (18” x7”x 30’) as a ridge. There is no attic- all ceilings are cathedral. We used 2x10’ rafters on 16” centers to span a 12’ wide roof plane on each side of the ridge beam. We have approx. 23 rafters for each side
We find on one eave wall side, our 2x10 rafters are uneven on the top plane by as much as 1.5” high.
What can we do before mounting the 5/8” roof decking?
F Yockers
I might just do that and while I’m at it I will unsubscribe from this Forum if other replies will be as mean spirited as yours.
Have a good day and I hope the homes you inspect will encounter a better attitude from you.
F Yockers
Measure twice, cut once. Your roof is now out of plane. You either absorb the problem with your sheathing and it look like crap or you take it down, IMO. But for the record, we are not a DIY forum.
