Can you straighten a 24 by 24 garage roof?

SDE · Mar 22, 2018

Thank you, I will give Dad's address, can you have it done by June?

The shingles are in really bad shape and need to be replaced, but if you put a string on the West peak and run it diagonally down to the lower East end you will see that there is at least a two inch depression or dip in part of the roof. Maybe even more than that. If you look from the eves to the peak it is very noticeable. My brothers and I feel that to fix this, we will need to remove the entire roof and rebuild it from the upper plate. The 2 by 6 trusses are on 4ft centers, with a 2 by 4 between them, going from the peak to the upper plate. This is what most likely has caused this problem.

Do you think that a complete rebuild is the easier than attempting to straighten it? Unless the weather becomes a factor, I have the time to do it this Spring or summer.
TY
SDE

ss55 · Mar 22, 2018

I would look at the trusses and walls for bows, joints that have pulled apart and broken beams. One or more triangle structures is failing.

showcrop · Mar 22, 2018

More info please. how big is the garage? what is the span? more specifically where is the sagging area? how big is the sagging area? Has it had a heavy snow load?

JDEM · Mar 22, 2018

I have straightened many. Make sure the rafters are fixed and/or reinforced. Run some 2 X 4s length-wise spaced 24" on center and shim them so the roof is flat. Then put on steel roofing.

SDE · Mar 22, 2018

The garage is twenty-four feet by twenty-four feet. There are not any posts in the center of the garage. The worst area of sagging is about seven to nine feet from the west end and is about eight feet from the peak. From inside the garage, we can not see any of the plywood having pulled away from the trusses. i did not see any sagging of the plywood and so i would assume that one or more of the trusses is sagging. How do you jack one or two of them up and get them locked in to place, without them getting to high or settling back down to low?
SDE

JDEM · Mar 22, 2018

Like this.

Grandpa's Fords · Mar 22, 2018

If you are going to hire this done or do it yourself you may have to consider that the roof deflection is only part of the problem. that deflection has to push to somewhere else most likely the outside walls.
So to correct you will be correct the walls then rebuilding the roof.
Price whole garage replacement, many lumber yards sell packages that can be modified to your needs. A good contractor can fix the issue but the labor may be more than the cost of a new structure.
From your description that's what I can gather.
Good Luck!

544hydro · Mar 22, 2018

Is there a ridge beam? Are the rafters 2x4? That's what I ran into once on a sagging roof. We put in a ridge been and added 2x6 rafters and resheeted and shingled.

showcrop · Mar 22, 2018

(quoted from post at 05:13:43 03/22/18) Is there a ridge beam? Are the rafters 2x4? That's what I ran into once on a sagging roof. We put in a ridge been and added 2x6 rafters and resheeted and shingled.

SDE stated that it is a trussed roof.

showcrop · Mar 22, 2018

It sounds like you need to get up on your step ladder and examine the trusses in that area. It would be very hard for the main chord to deflect like that without one or more of the internal braces coming loose and moving. I bet that a closer look will tell the tale.

Russ from MN · Mar 22, 2018

Yes it can be fixed, but first you have to figure out where the problem really is. stretch a string down the ridge, and then down each rafter. I fixed one similar last summer, used a come-a-long to pull the walls back together, and then stretched a cable across tight to keep them in place and left it there.

jm. · Mar 22, 2018

JDEM What keeps condensation from forming on the underside of the metal and then rotting out the two by fours. Around here we have to put insulation under the tin or won,t last 10 years like you are doing.

DPittman · Mar 22, 2018

All good responses save one thing that hasn't been addressed, how many layers of shingles? If there are 2 to 3 layers it will straighten a whole lot quicker with all that weight off. Then it's just a matter of keeping it straight after new covering is applied. Wondering if I could do that with my body? DP

ss55 · Mar 22, 2018

SDE,
Can you confirm if your dad's garage is built with prefabricated trusses or is it built with rafters? Prefabricated trusses are factory made, usually fastened together with heavy gauge sheet metal plates that are pressed into the wood at every junction. Rafters are stick built on-site usually nailed together.

It is common for a rafters to come apart, the walls spread apart (bow out) under the weak rafter, and the rafter and roof sag as the walls spread. It is less common for trusses to fail, but it happens, usually a beam breaks more often than a joint pull apart.

A common repair is the pull the walls back into place with a cable or additional lumber.

David G · Mar 22, 2018

Sagging is do to slipping somewhere in the rafter.

Run a string down your outside walls, and then down the center under the rafters, that should show you where the issue is.

Personally, I would correct ore replace structure over putting straight roof over sagged.

gregww · Mar 22, 2018

(quoted from post at 03:52:05 03/22/18) Thank you, I will give Dad's address, can you have it done by June?

The shingles are in really bad shape and need to be replaced, but if you put a string on the West peak and run it diagonally down to the lower East end you will see that there is at least a two inch depression or dip in part of the roof. Maybe even more than that. If you look from the eves to the peak it is very noticeable. My brothers and I feel that to fix this, we will need to remove the entire roof and rebuild it from the upper plate. The 2 by 6 trusses are on 4ft centers, with a 2 by 4 between them, going from the peak to the upper plate. This is what most likely has caused this problem.

Do you think that a complete rebuild is the easier than attempting to straighten it? Unless the weather becomes a factor, I have the time to do it this Spring or summer.
TY
SDE

find it hard to believe that 2X6 trusses failed in this wat over a 24' span. Are they actually "W" trusses or just rafters? Is there a 2X4 (kingpin) at the center of each truss? A kingpin, (what we call them locally) is a 2X4 or 2X6 placed verticaly from the bottom chord to the top chord. (horizontal members) While I would not recommend 8" spacing, it would work if 2x4 perlins were placed on top of 2X6 trusses rather than between them. As others have noted, if it sank, something else, like the side walls have to have moved outward. If this s the case, putting tin on top of all this, without first correcting the initial p[problem, could cause complete failure. I don't know where you are located, and you don't mention your potential snow load. In repeat what I said earlier. A 2X6 TRUSS would hardly fail over a 24' span. I can see where 2X4 perlins placed between the trusses could dip, but not a true truss.

gregww · Mar 22, 2018

Pics from inside and out might help if possible. Greg

Crazy Horse · Mar 22, 2018

SDE ...... not sure if you have really confirmed for sure it is a trussed roof system. The term "truss" can be used loosely at times. Also, is it a factory engineered truss or something that somebody scabbed together themselves in their back yard, can you guess by looking at them? Someone mentioned the wall bowing out, a good check. I don't think a real engineered factory-made truss should sag from my limited experience.

Stephen Newell · Mar 22, 2018

You see a lot of houses with depressions more than that. Unless it really bothers someone I would leave it alone and replace the shingles if it needs it. To fix it would either involve tearing off the entire roof and reframe it or re-enforce what is there with steel. Either way it would be a lot of work.

whereswaldo · Mar 22, 2018

A real truss won't spread. He's describing a 'King' post truss. If the walls are bowing, then the bottom chord is coming apart. My in-laws had a garage built in 1975 and only a year later the roof was sagging.(not a truss) I bought a couple cheap 'come-a-longs' and pulled the eave walls back together. This was in 1975 and it's still standing, lol. Those cables are so tight you could have played a tune on them.

ss55 · Mar 22, 2018

If your dad's shingles are poor enough to have leaked for a long time, and the sheeting is unsupported across four foot sections, it's possible that the sheeting is weak enough to sag several inches on its own. That does not explain the sagging ridge line, that is probably a different structural problem.

Look over the trusses and the underside of the roof well before you tear anything apart or order materials. Try pushing up on the sagging spots from below with a long 2x4 to see how much they give. When you tear off the old shingles, be careful to warn everyone on the roof about the soft spots or mark them well so no one falls through the roof. A rescue call, ambulance ride and a visit to the emergency room could easily cost more than the replacement roof.

Crazy Horse · Mar 22, 2018

Waldo ..... good comment. I made a set of king post trusses years ago but it was for a small building, the bottom stringer was 14' long on a 12' wide building (one foot overhand at each end) ..... but there was no join in the middle of the bottom stringer where the king post (I assume that is what you would call that center vertical part of the truss) was located. I suspect the bigger the building and the bigger the truss, the more important it is to be designed and built properly, that only makes sense.

Spook · Mar 22, 2018

I suspect it?s not a real truss. I?ve used a come along to pull things straight, pushed up the ridge, and added collar ties, rather than cables.

showcrop · Mar 22, 2018

(quoted from post at 06:47:59 03/22/18) SDE,
Can you confirm if your dad's garage is built with prefabricated trusses or is it built with rafters? Prefabricated trusses are factory made, usually fastened together with heavy gauge sheet metal plates that are pressed into the wood at every junction. Rafters are stick built on-site usually nailed together.

It is common for a rafters to come apart, the walls spread apart (bow out) under the weak rafter, and the rafter and roof sag as the walls spread. It is less common for trusses to fail, but it happens, usually a beam breaks more often than a joint pull apart.

A common repair is the pull the walls back into place with a cable or additional lumber.

SS55, SDE stated that it has 2x6 trusses 4 feet apart.

SDE · Mar 22, 2018

I used the word truss, but I should have said that they were rafters. My Dad hired a new to the trade individual to build this garage. It was his first job. I do believe that he built them also. The ridge line is very close to being straight. You have to look pretty close to see that it has a slight sag that is just above where the worst sag is located. We have not checked the walls for straightness, but no one has noticed it to be out of alignment. We walk past the corner and along the side of the garage to go to the house.

I have found that I will find a job easier to do if I take enough time to mental prepare for it. So I was hoping to be able to use some one else's expertise.
My brother's will want to do the rebuild and I wanted to check and see if I had another option. Dad will be paying for it,and I want to have this looking good enough that it does not prevent the property from being sold after he is gone.

TY
SDE

Frank 41 · Mar 22, 2018

The easiest way is to find the square root of 24 and go from there.

Can you straighten a 24 by 24 garage roof?

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Well-known Member

Member

Similar threads