nealtw
Contractor retired
Yes I understand that but it would still be 20 ft from the gables so that would not be close enough. You would still have a problem somewhat less.
Sagging Roof on Shop
- Thread starter Cooter85
- Start date
Help Support House Repair Talk:
nealtw
Contractor retired
No, collar and rafter ties are both called for, for a reason. even if you could hold the top together, the rafters sag and let the walls out.
When you build it you only have so many choices.
Stiff walls like balloon framing.
Ridge beam
Trusses.
Rafter ties, the floor would do this if the walls were stiff.
I just talked to an engineer about installing a beam.
He said the same as I thought the roof has to be brought back into shape first.
He said he has called for beams and inspected the beams after they were installed and didn't know how they get the roof back in shape.
The rafters will only sag if they are undersize. They are free to bow in any roof with the ends fixed and connected to the floor joist. I do agree this framing of the knee wall should never been set on the floor like that and not ties to the first floor framing balloon or other. But in this roof the collars were not enough or most likely not connected well enough for the spread.
My feeling is the rafter size is fine.
nealtw
Contractor retired
OK but all rafter roofs have both rafter and collar ties, you won't find an engineer that would approve what he has.
Vaulted trusses always have the inside at a lesser pitch. The lower member acts as both the collar and the rafter tie.
The reason that an engineer would not approve what he has, is because of the knee walls, which have rotated.
In conventional framing when the ceiling joist are perpendicular to the rafters, collar ties are common and an acceptable practice.
nealtw
Contractor retired
Yes ceiling joists are rafter ties.
Of course the strongest place to put the collar is by making it the ceiling joist for the floor below. My house has rafters and no upper collar tie just the ceiling joist and it has been standing 150 years.
This building was designed with 2 serious flaws. 1 is the ceiling joists running 90 to the rafters and 2 the knee wall is not solidly supported from the first floor framing to prevent it from rolling out such as balloon framing may have done by putting the studs in bending. It well could have still rolled out though just from the first floor plate and could have been a bigger problem. Something has to react the outward force and the only thing in the design to do that is the collars that have proved to be not enough or not attached well enough.
You are correct none of this may be to code or pass approval.
The question remains he has two problems one being how to correct the structure and two what is the correct fix within his budget hopefully and two that will still give him a useful area. All that has to be done in a safe manner and the end result should remain safe.
This building was designed with 2 serious flaws. 1 is the ceiling joists running 90 to the rafters and 2 the knee wall is not solidly supported from the first floor framing to prevent it from rolling out such as balloon framing may have done by putting the studs in bending. It well could have still rolled out though just from the first floor plate and could have been a bigger problem. Something has to react the outward force and the only thing in the design to do that is the collars that have proved to be not enough or not attached well enough.
You are correct none of this may be to code or pass approval.
The question remains he has two problems one being how to correct the structure and two what is the correct fix within his budget hopefully and two that will still give him a useful area. All that has to be done in a safe manner and the end result should remain safe.
nealtw
Contractor retired
Even with your joists going the other way , your sub floor is holding it and you have intersecting walls up and down,.
