Sagging roof question

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  #1  
Old 03-16-19, 09:32 AM
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Sagging roof question

This question may possibly be a rhetorical one. As some of you know I am replacing the fascia and trim along the front of my home. The reason being is because the proper flashing was never put up and some of the wood rotted. I am doing this before I get roofers here to put up an new roof. I just took the rotted gutter fascia board off above the garage. My roof is sagging above the garage and that needs to be addressed by the roofers. Anyways, I am wondering if I should bother putting up the new fascia or not since it would be getting fastened into these sagging rafters? I would hate to do all this work just to have it be taken down, but I do not really want to pay the roofers to put it up either, as I am already going to have them put on the drip edge. What do you think? I am getting some estimates next week and want to get the new roof asap. Thanks,
 
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Old 03-16-19, 09:48 AM
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Perhaps I should just put up the pine board fascia with limited fasteners for now and see what the roofers say before putting the flashing and gutter back up. Seems logical
 
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Old 03-16-19, 10:16 AM
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We don't know why or where it's sagging or how they intend to fix it, so it's hard to say.
 
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Old 03-16-19, 10:21 AM
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How is your roof sagging. When facing the front of the house does the fascia bow downward? Or, are your roof rafters sagging so there is a dip between the fascia and roof's peak?

Here are instructions for posting pictures.
 
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Old 03-16-19, 10:21 AM
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Thanks. It is the rafters that are sagging so they will need to be sistered. Also a couple pieces of sheathing will need to be replaced due to water damage from not having a drip edge.
 
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Old 03-16-19, 10:30 AM
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Might be tough to see the sag from the pics. it is above the garage smack in the middle.

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Last edited by PJmax; 04-07-19 at 08:51 PM. Reason: reoriented/cropped/enhanced/resized pictures
  #7  
Old 03-16-19, 10:46 AM
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Fixing a roof like that is more complicated than you think. And I doubt it will ever be perfectly flat unless it's completely rebuilt. Sistering a bowed rafter will usually just succeed in making the bow a little better. The sag and the weight of the roof will usually just bow the new rafter as well.

But yes, if they intend to sister the full length of the joist, the fascia needs to be left off, because the new rafter need to be cut to length to match the existing ones, inserted up through the fascia, then rolled upright with a bar between the rafters and then be slid (beat over) until its next to the old rafter. They might be able to do it from inside if they make the new rafters as short as possible.

Rather than sister, I imagine that it would be better and easier to just install a beam crosswise under the existing rafters at the midpoint in their span. This beam would sit on the top plate of the left and right walls, be blocked within the wall so that it can't roll, then above the beam, a top plate would be installed across the bottom of the rafters and each rafter could be braced up individually off of the beam. If it was done that way, the soffit and fascia could be done anytime.
 
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Old 03-16-19, 11:02 AM
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Thanks. I like the idea of the cross beam. This is a 50 year old house and I tend to think that the sagging is due to years of settling, but I am no expert. I think I am just going to attach the pine board with as little screws as possible for now to keep critters and weather our of my garage for the time being. When I am getting my estimates I will ask if they would sister or cross beam, and see how that goes. I cannot wait until this is done and I can find something else to stress me out.
 
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Old 03-16-19, 11:10 AM
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Not all roofers work on framing, some will just limit their carpentry work to replacing decking as needed. Just something to keep in mind.
 
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Old 03-16-19, 11:19 AM
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thanks for that info marksr
 
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Old 03-16-19, 11:27 AM
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FWIW, I wouldn't let most roofers frame a doghouse.
 
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Old 03-16-19, 12:06 PM
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LOL. Aw man! That is a chilling reality. I would figure this is something roofers run into constantly.
 
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Old 04-07-19, 08:31 PM
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Hi folks. I think I am going to try to fix these sagging rafters myself before I get the new roof. I took some pics from inside the garage. Excuse the mess. My home was built in 1969 and he rafters in the garage extend the whole length of the roof without any bracing. This is why the roof is sagging a bit. There are some ceiling joists running from wall plate to wall plate in from the middle to the back of the garage (I am storing extra wood and trim pieces on them. The most forward one to the garage door is where I was thinking of bracing. Should I sister this joist and brace from there? Also, how will this type of bracing raise the sag? Will it raise the sag or just support the rafters? More questions after these.
 
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Old 04-07-19, 08:42 PM
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well I'm exceeding my attachment quota. Any suggestions?
 
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Old 04-07-19, 08:52 PM
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I took care of your attachments. They were gigantic. Try to size them a little smaller.
I go thru and check them anyway.
 
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Old 04-08-19, 06:12 AM
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Generally adding bracing to an already sagging roof can't push out all the sag but it can usually take some of it out. One thing you need to be concerned about is the bottom of your braces. What are they resting on? Will that member start to sag when you put a load on it. I've seen where people install braces to solve a roof sag but end up putting a sag in the ceilings below because they just ran bracing down to a ceiling joist spanning a room.
 
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Old 04-08-19, 08:46 PM
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Thank you PJMAX. Must be the high res on the phone. Yes Pilot, I see what you are saying and I do not want that to happen. Maybe i shouldnt sister that 2x6 beam and just put another right in front of it. Here are some pics. Excuse the mess. I have a bunch of stuff in here. I apologize for the angles of the photos as well. It's a small garage.

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Last edited by PJmax; 04-09-19 at 06:18 PM. Reason: cropped/resized/enhanced pictures
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Old 04-08-19, 09:01 PM
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When I said "beam" in post #7, here is what I meant... a "beam" is a structural component, a "header", with strength sufficient to resist deflection... something that can help carry your roof load... that you could then build off of to correct the sag.. The size of the header needs to increase with both the span and the amount of weight. A beefy beam could be a double or triple 2x12. The biggest factor in your case is the span... the distance of the beam from end to end. You have provided no info on that. I assume from your first photo that it is maybe 11 or 12 feet. Please provide that info.

A single 2x6 is not a beam, it's a ceiling joist, and even if you double it, a 2x6 that spans 12 feet is not a big enough beam since that is over spanned- a 2x6 header is weak and cannot resist that kind of deflection.

I will tell you right now, (since we now have more photos to look at) the other reason you have a sag is that your roof has no rafter ties to tie the front and back walls of the garage together. In all likelihood your ridge has also sagged because with no rafter ties, your rafters are pushing out on the front and rear exterior walls, bowing the top plates outward, creating a dip in the ridge, a bow in the fascia, both separate problems from the bow from rafters being over spanned. Carefully measuring the length of the garage from top plate to top plate (checking it on the ends, comparing that measurement to the length down the middle) would confirm this.
 
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Old 04-09-19, 05:33 AM
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Since you don't have anywhere good to simply brace down to I would consider sistering the roof rafters top to bottom and possible add some collar ties further down. Best would be collar ties all the way down at ceiling level. For something unorthodox you could build trusses in place.

 
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Old 04-10-19, 07:32 PM
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Pilot Dane- thanks. XSleeper, I will get the measurements tomorrow. The other side of the roof over the garage is not sagging because it is properly braced in the attic (along with the rest of the roof). As far as I can tell ridge isn't sagged either. The problem appears to be confined to the one side which goes over the garage, right smack in the middle of the rafters. The ridge is pretty much where the garage ends and turns into my laundry room. Because of this there is really nowhere for me to put rafter ties since i cannot access more than about 4 ft of the rafters on the other side of the ridge. I'm guessing this is why they are not present and why i am having this problem. I will take some more pics tomorrow so you can see what I am talking about, but I'm pretty sure my walls are not being pushed out. Thanks for the info. I learned a lot and now I know what to look for as I am better understanding what is going on here. Sorry I'm being so slow and confusing in explaining this. This is all new to me.
 
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Old 04-11-19, 06:02 AM
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What condition is your roof? Will it need re-shingling anytime soon? That would be a great time to address the sag.
 
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Old 04-11-19, 11:02 AM
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Roof is getting replaced ASAP, which is why I'm trying to figure this out. The folks I'm using for the roof do all types of construction, however I am trying to do this part myself if possible. Here are some more pics. This is where my garage ends and turns into my house. The other pic is in my attic showing how everything is braced on the other side of the ridge that is not over my garage.

My garage width from wall to wall is 140", a little under 12ft. I'm going to have to get creative to measure my rafter span so that will be coming soon.

Thanks.

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dmbktts voted this post useful.

Last edited by PJmax; 05-07-19 at 12:47 PM. Reason: resized pictures
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Old 05-07-19, 12:39 PM
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Any update?
My house was built around the same time and we have the same issue.
Seriously looking at your pics is like looking at my own "attic" area.
We want to re-roof within the year too so I would love to hear if you resolved this.
Thanks!
 
 

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