Roof issue

[Paesano]

No, not Gampel. Since everyone is asking home questions I figured I would throw mine out there. First, I must disclose that I live in rural upstate NY and no one knows how to build a damn house up here. The skilled labor sucks. I miss the old Italian carpenters of southern CT.

So now my roof. I have never seen this issue before and I am baffled as to what they did wrong. I want to figure it out before contracting someone to fix it because I don't trust anyone up here to figure it out. Our house faces west and the ridge of the roof runs north/south. In other words, the water runs down toward the front and back walls of the house. The house was built in 1997 but we bought it in 2000. It has a ridge vent and soffit vents. Air flow is not blocked and insulation appears to be decent. The problem is that I am getting sagging between the trusses. It is only happening on the west or front side of the roof and only near the peak. The sagging is occuring from the peak down about three feet. The other side of the roof is fine and most of the west side is fine too. It is sagging in a few places but not between every truss. It is hard to say how much it is sagging but it varies. The worst might be 2 or 3 inches.

Any ideas?

 

[Dove]

Are the sagging areas viewable from an attic space?

 

[Paesano]

I do have access and the areas that sag only show up as more light coming in from the ridge vent area. But I haven't tried to get a really close look yet. Maneuvering through the trusses is a PITA. I'm not as flexible as I used to be. But if there is something I could do to gather more info, I will suck it up and work my way over to the worst areas. The biggest fear is slipping and putting my foot through the foyer ceiling.

 

[tdrink]

What is the truss spacing on center? How thick is your roof deck? Plywood or OSB?

Are there little clips that bridge the deck between the trusses?

Builders are allowed to use roof decks that are, imo, overspanned. They put H clips between the sheets so the sheets are less likely to distort at the edges but that doesn't help the top edge of the uppermost sheet. That spot also gets the most heat and can get some rain and snow on it that gets driven through the ridge vent.

 

[Dove]

6 years ago we were house hunting and there was a house that had a sag that really got my attention. The area was over a large open space in the house. They had an open kitchen/living room with high ceilings.

It was just assumed that the spaces between the rafters were farther apart than today's building code allows. And over time the plywood sheets sagged.

 

[pnow15]

Is your roof leaking? Well, if it ain't broke, down fix it.
Or you could try adding more trusses, which might required some clever handiwork.
You might consider adding jacks to the to lift the sag or hold it in place if he roof has an attic floor under it.
Heck, I had to put a system of jacks and four by fours under my Florida house to keep it from sagging in the middle due to settlement.