Sagging Roof Insight

[Large Wooden Badger]

Just purchased a lake house, built in 1977, shallow roof pitch.

Has an attached 2 stall garage, added fairly recently.  Ridge line is sagging a couple of inches, as is the field on the front of the house.

Appears to be 2x6 ridge board and rafters consistent with the rest of the house, but there are no purlins or other support.  Only the garage is sagging.

Whats my best course of action?

Would I be better off running a beam of sufficient size some distance under the ridge and then jacking up the ridge and putting in supports to the new beam, or build like a stud wall under the ridge as it currently is?

Then my guess for the sagging field would be to add a purlin along the front.  The back is fine, as the roof is truncated and only goes about halfway down and is supported by a wall.

The walls are not bowed, I've already checked that.

Looking for ideas, I don't want to tear it off and start over.

[Mr_Mike]

You need to move the load to the walls and then to ground. A stud wall in the attic will not achieve the desired result unless you put in sheer walls or diagonals. i.e. a truss. May as well just use a truss or truss-like thing in the first place.

The ultimate ideal would be to replace the ridge beam with one of sufficient size. But, you'd pretty much have to tear off the roof.

I think that adding a sufficient beam under the existing and then crippling up to the existing ridge would be easiest. Due care in running the load to ground on each end being necessary.

Logistically, you would de-skin a gable end and slide in the beam. Prop up the existing ridge beam and cut the columns down. Insert new beam and cripple the existing into place.

[Large Wooden Badger]

That sounds good, that was my original intention.  Its sad they didn't spend the extra hundred dollars to do it right in the first place.

Whats weird is they decked the whole thing with OSB like they were going to use it for storage, and then finished the garage leaving no access.

Would have cost less to do the structure correctly then to deck the whole thing.  I have no way of getting into it without going through drywall and OSB first, I have just enough room to get a flashlight and camera in from the house attic to see what I am up against.

[Mr_Mike]

Well, is it a firebreak? If not, cut a attic stair in it.

[Mr_Mike]

Alternate, add a ridge-like beam at mid-span of the long rafters. That will require new columns to ground in the walls, but might be easier to do.

[tomsteve]

 Ridge line is sagging a couple of inches, as is the field on the front of the house

what is the "fieild?"

got some pics? theyd prolly help us help you a little better

[Mr_Mike]

More thoughts. You have a ridge board, not a ridge beam. I assume you have collar ties and/or ceiling joists to pull the walls in?

[Snipe Hunter]

What is the pitch of the roof? Shingles? Rolled Roofing?

You can download Pitch Gauge on your phone and it measures your pitch simply by taking a picture of the side.

Tell me about the field in front of your house

[Cooler]

A second set of horizontal rafters higher up from the first may prevent the roof from sagging.  Use a ratcheting webbing to try to pull them back in line.  It should raise the ridge back in place.  Then nail in horizontal rafters to keep them from spreading again.

How many layers of asphalt shingles are on the roof? If it is more than two then it might be the weight that is the culprit.

[Large Wooden Badger]

sorry all, I stepped away and forgot to check back.  I only have a couple of limited pictures






That one upright board doesn't appear to be any kind of support, I'm not sure what purpose its serving.