Sagging roof question

1775 Views 8 Replies 6 Participants Last post by paintdrying, Dec 20, 2012

han0522

Discussion Starter · Dec 18, 2012

Hello all,

I'm new to these forums and I'm a new home owner. I've been in this home for ~6 months. It has a shop/shed in the backyard that is at least 10 years old (couldn't find the records) that is in need of some repairs; mainly, replacing the siding, the door (bottom is rotted), and the roof. I have some ideas on how to fix the first two but am seeking advice on the roof.

As you can tell, the roof sags in the middle and the two long walls (the structure is ~20 ft x 40 ft) are being pushed out slightly so they are out of plumb. The reason is obvious in that the roof has rafters but no horizontal joists, as seen from these images:

Here are some additional pictures of the rafters:

I figure the roof structure needs horizontal joists to keep the roof level and to keep the roof from pushing the walls out.

My question is is there some way to "jack" up the roof and install horizontal joists to repair the above problem? If so, is this something an individual can do with limited experience or do I need to hire a roof contractor?

Thanks for any help,
Chris

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shazapple

· #2 · Dec 18, 2012

Yes, this can be done if you are confident in your abilities. Some bottle jacks and thick posts/beams to distribute the load, maybe some comealongs to help pull the walls in. Check to see how much sag there is in the rafter itself.

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jagans

· #3 · Dec 18, 2012 (Edited)

First of all, using 2 x 4's for rafters is limp. They should at least be 2 x6's The ridge pole should be 2 inches deeper than the rafters. All this notwithstanding, the real problem is that whoever built this place the collar beams way too high. What you need to have is known as tied rafters. Lika a collar beam, but only one third up on the rafters, not way up top like yours are.

First, put a strongback on the outside of the two long walls. Run a 5/8 inch Eye Bolt through the strongback at 1/3 and 2/3 the length of the wall and put a couple of large flatwashers and a nut on the outside. Eye inside. Hook two comealongs up inside and start cranking the walls in as you jack the ridge up with a T. Jack and pull the walls a little past straight. (so they are actually bowed in a bit. Use a string line for this. Id say a 3/4 inch should do it Install the tied rafters 2 x 6's on every set of rafters and bolt with 2- 5/8 HD Galvy bolts on each one, on each end flat washer on both sides. Tighten till wood is dimpled the depth of washer. (Air Tool Work Good Here) Remove jack and cables. Check your ridge, you will probably have split the ridge caps, and will have to replace them. Were it me I think I would sister a 2x6 at least on every other set of rafters, and probably all of them. 2 x 4's are limp for rafters. Oh, I said that already. Sorry

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Windows on Wash

· #4 · Dec 18, 2012

+2

Seems almost easier to rebuild the roof assembly with better materials than to try and fix it.

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jagans

· #5 · Dec 18, 2012

Yeah, I think you are correct Eric. Very good point. Sometimes I miss the forest for the trees.

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Windows on Wash

· #6 · Dec 19, 2012

jagans said:
Yeah, I think you are correct Eric. Very good point. Sometimes I miss the forest for the trees.

Check your email James....

Eric

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tinner666

· #7 · Dec 19, 2012

As a side note, if you do try to raise it for some reason, you can pull the walls in some while jacking the ridge. If is complicated to do without hurting somebody though.
If you do it, DO NOT use bottle jacks. We used too and always checked for plum. That didn't matter one day. The bottom of the 4x4 shot out, or the jack tipped, or something. The 8' 4x4 went through 2 walls removing one stud and bouncing off another wall and came back into the room we were in. Somehow, it went between two of us going one way and then between two others coming back. No, we could not follow it with our eyes. We only had the skid marks and holes in the walls for clues. They move fast when they feel the need, I guess.

We only use floor jacks now.

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han0522

Discussion Starter · #8 · Dec 19, 2012

tinner666 said:
As a side note, if you do try to raise it for some reason, you can pull the walls in some while jacking the ridge. If is complicated to do without hurting somebody though.
If you do it, DO NOT use bottle jacks. We used too and always checked for plum. That didn't matter one day. The bottom of the 4x4 shot out, or the jack tipped, or something. The 8' 4x4 went through 2 walls removing one stud and bouncing off another wall and came back into the room we were in. Somehow, it went between two of us going one way and then between two others coming back. No, we could not follow it with our eyes. We only had the skid marks and holes in the walls for clues. They move fast when they feel the need, I guess.

We only use floor jacks now.

Yikes

.

Thanks for the advice everyone! I'm going to look the building over this weekend and see how comfortable I am with jacking the roof up while pulling the walls in. Hopefully I will be. Otherwise we might opt for having the roof replaced.

Thanks again!
chris

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paintdrying

· #9 · Dec 20, 2012

Your problems sound cosmetic to me. You could just as well leave the shed alone, it would be fine as a standing structure. If that place was on my property I would dis assemble it, pour a new slab and build a whole new building. It is one way or the other, do not bother patching what you have.

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