# Sagging rafters



## ruissar (Jul 3, 2012)

I have a customer that wants a sagging section of roof jacked back up. Its a very tall, steep roof and there is a section of rafters without braces, that section is right over the span of the living room, which is why there are no braces I take it.. I was thinking either span a beam from the top of one living room wall to the other and brace the roof off of that or just span a beam across the rafters themselves using lag bolts and maybe the sag will be corrected when tightening the bolts, any advice?


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## Calidecks (Nov 19, 2011)

ruissar said:


> I have a customer that wants a sagging section of roof jacked back up. Its a very tall, steep roof and there is a section of rafters without braces, that section is right over the span of the living room, which is why there are no braces I take it.. I was thinking either span a beam from the top of one living room wall to the other and brace the roof off of that or just span a beam across the rafters themselves using lag bolts and maybe the sag will be corrected when tightening the bolts, any advice?


Are there ceiling joists?


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## Jaws (Dec 20, 2010)

Pic is worth a thousand words. 

Probably have to add beams or atleast double/tripple some ceiling joists, depending on spans, to the ceiling in the living room to brace some perlins to.


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## Jaws (Dec 20, 2010)

If there is ceiling joists. Is it a vaulted ceiling?


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## griz (Nov 26, 2009)

ruissar said:


> I have a customer that wants a sagging section of roof jacked back up. Its a very tall, steep roof and there is a section of rafters without braces, that section is right over the span of the living room, which is why there are no braces I take it.. I was thinking either span a beam from the top of one living room wall to the other and brace the roof off of that or just span a beam across the rafters themselves using lag bolts and maybe the sag will be corrected when tightening the bolts, any advice?


Due to the terminology you are using I would question whether you should be attempting this repair.

You referring to collar ties?

Why would you use lag bolts? 

How would tightening the bolts straighten the rafters?


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## Jaws (Dec 20, 2010)

griz said:


> Due to the terminology you are using I would question whether you should be attempting this repair.
> 
> You referring to collar ties?
> 
> ...


Have to agree. I was typing a negative response about the lags when I caught this.


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## Calidecks (Nov 19, 2011)

Not to mention, if for some reason (not sure how) tightening blots straightens sagging rafters, then you would have a lot of weight on lag bolts, not good.


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## CarpenterSFO (Dec 12, 2012)

I think the O.P.'s theory is to set a purlin, unsupported, and use lag bolts to snug it up to the un-sagged roof joists at the end.

To the O.P.: talk to the engineer you usually work with, get a knowledgeable answer based on the exact conditions, and go pull a permit, using your ability as a licensed contractor. If you're not careful, and you just try one of your existing ideas, you might pitch a beam through the living room ceiling, or shove the living room walls apart, or wreck the roof, which has gotten used to that sag, or kill someone, etc., etc. That purlin might give way a month or a year from now.


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## Calidecks (Nov 19, 2011)

CarpenterSFO said:


> I think the O.P.'s theory is to set a purlin, unsupported, and use lag bolts to snug it up to the un-sagged roof joists at the end.
> 
> To the O.P.: talk to the engineer you usually work with, get a knowledgeable answer based on the exact conditions, and go pull a permit, using your ability as a licensed contractor. If you're not careful, and you just try one of your existing ideas, you might pitch a beam through the living room ceiling, or shove the living room walls apart, or wreck the roof, which has gotten used to that sag, or kill someone, etc., etc. That purlin might give way a month or a year from now.


Exactly if those are collar ties like Griz questioned, you might want to consider what that will do to the walls if you put a load on them.


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## Bigheadnick (Jan 14, 2013)

Really is hard to brainstorm solutions without a picture of the problem. Are we talking about the ridge sagging along with walls bowing outward or are we talking about midspan rafter sag? Or something else I'm not picking up? If its the former then I would suggest jacking the ridge and simultaneously pulling the walls in using a string and block to check it off then add the collar ties or ceiling joist (u didnt explain which it is) where missing or in the case of vaulted ceiling a few exposed beams. If it is in fact ceiling joist I would add collar ties as well(typically1/3 up the beam). In the case of the latter, You're hands are pretty tied unless you want to rip off the entire roof and use new wider lumber for rafter stock. U could prevent further sagging by sistering up new rafters to the existing but u may run into load issues. As mentioned before, in either case talk to an engineer.

Also other things to consider are the inevitable damage to the inside walls when u do anything(ie drywall/finish/windows all possibly cracking actually likely cracking) the span of the room which will determine the weight of the beams putting more load on the walls as others mentioned etc... Pictures ! we need pictures!


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## ruissar (Jul 3, 2012)

Sorry I couldn't figure our how to post a pic, I've added the picture up top


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## jlsconstruction (Apr 26, 2011)

Just add collar ties purlins and braces. I found a pic to help you, if your not going to consult an engineer.


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## greg24k (May 19, 2007)

At this point I doubt you will get the sag out, because that lumber is old unless you do a structurally designed repair,i.e notching the rafters, straighting them out and sister them up which is a big job. 

If there is no wall beneath the ceiling, and you try to jack rafters up and use Purlin Bracing you will have a sag in the ceiling, because the bracing should rest on top of a bearing wall...and if they rest on the ceiling joist alone, they pass that load to the ceiling causing a sag.

You should also have collar ties at least 1/3 of the distance down from the ridge before the wall pushes out.

It looks like there was a slate roof before, and it was removed, then plywood was installed over the furring strips to accommodate new shingle roof.


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## jlsconstruction (Apr 26, 2011)

Could have been shakes I see houses like that all the time


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## 18withtools (Jan 13, 2013)

I think your in over your head when it comes to the engineering and planning part. I would be to, we gotta learn sometime but I would consult a pro engineer to learn, not just guys on the web. There are so many variables an not just a pic can show.


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## ScipioAfricanus (Sep 13, 2008)

18withtools said:


> I think your in over your head when it comes to the engineering and planning part. I would be to, we gotta learn sometime but I would consult a pro engineer to learn, not just guys on the web. There are so many variables an not just a pic can show.


As true as this is, not all framing solutions require an engineered solution.
The IRC has specifications for framing that any knowledgeable designer, Archy, carpenter etc. can design a solution for.
This particular situation looks like it needs an engineered solution but I can't tell for sure from just a picture.

Andy.


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## KennMacMoragh (Sep 16, 2008)

ScipioAfricanus said:


> As true as this is, not all framing solutions require an engineered solution.
> The IRC has specifications for framing that any knowledgeable designer, Archy, carpenter etc. can design a solution for.
> This particular situation looks like it needs an engineered solution but I can't tell for sure from just a picture.
> 
> Andy.


It's up to the building department. He needs to talk to the building inspector and ask that question. My most recent job similar to this the inspector came to the site and offered a solution, told me I didn't need an engineer. Basically he said run a T brace across the span with supports running to the ceiling joists.

Another time I had one of these jobs in a different town and they required everything to be engineered and approved. This one required a full beam going all the way across. It's also important to understand what the word "approved" means. It means approved by the building official, not the engineer. Half way through the job we called the engineer to make adjustments on the design. It all looked good except the inspector wouldn't sign it off, it's got to go through them first.


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## greg24k (May 19, 2007)

KennMacMoragh said:


> It's up to the building department. He needs to talk to the building inspector and ask that question. My most recent job similar to this the inspector came to the site and offered a solution, told me I didn't need an engineer. Basically he said run a T brace across the span with supports running to the ceiling joists.
> 
> Another time I had one of these jobs in a different town and they required everything to be engineered and approved. This one required a full beam going all the way across. It's also important to understand what the word "approved" means. It means approved by the building official, not the engineer. Half way through the job we called the engineer to make adjustments on the design. It all looked good except the inspector wouldn't sign it off, it's got to go through them first.


I never met a building inspector who would say you don't need an engineer or Architect when it comes to structural situation, and say "just put a few braces here and there...". If he is wrong and something happens, that is a major lawsuit and I doubt this guys will strap themselves to pull that wagon. 
They can make a suggestion that you can take to your Architect or Engineer, but in the end they need that stamped letter or repair detail which they must review and approve.


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## ohiohomedoctor (Dec 26, 2010)

Strip the shingles and add plani patch to the low parts....


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