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Discussion Starter #1
Last year, I purchased a home that has a covered patio.. The cover consists of a lean-to, and it's sagging about 1" or so over a 12 1/2 ft span.

The roof pitch is right at 1/12.. so, it's pretty flat.

The span is 12.5ft, from where it attaches to the house, to the header. The span is composed of 2x6 pressure treated pine (not sure what grade), on 16" centers.

The cover is 15ft wide, with (3) 4x6 posts supporting the load. They are 7.5ft apart, and have double 2x6's nailed/glued together as the header. There is no evidence of sagging with the header.

The roof is 15x32's plywood, with a layer of tar paper, and shingles on top of that.

Everything that I've read, says that 2x6 pine should be fine for this on 16" centers with a span of 12ft. Why is this thing sagging so much? It's only 2 years old.

More importantly.. what can I do to fix the problem? I'd like to close the patio in, and put a ceiling in place, so going with 2x8's or bigger is out of the question. There simply isn't enough room overhead. Can I jack up the roof with bottle jacks, and nail/glue another 2x6 onto each existing one? Will this be enough support? Should I use a different type of wood?

Any help would be appreciated.. I don't know a great deal about the math involved.. but, I am capable of using a saw, hammer, and a nail gun. :)

Travis
 

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What part of the country do you live in?
Snow?

Is the sagging point just in the middle where the circle is, so the two rakes are okay?

If so, you may be able to jack that area up and sister on a couple more rafters.
 

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I agree with cleve. I would also put on an appropriate roof covering for that 1 in 12 pitch. Shingles are not designed to work on a nearly flat roof. I wouldn't be surprised if you find out that wood up there is waterlogged, adding a considerable amount of weight, compounding the sagging issue.
 

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Discussion Starter #5
Sorry.. Forgot about the location.. I'm in South Louisiana, so snow isn't a factor.

I considered the same for the singles, but the wood is bone dry. It looks like they used some sort of sealant as they laid the shingles down (not just the sealant strip on the single itself). Also, it hasn't rained here in over a month, so things are nice and crispy.

The roof sags all the way across.. The rake is the portion that hangs over past the header, right? If so, that is fine. It's only 12" or so.

I thought about using (3) 2x6's in the center, glued/screwed together, where it rests directly on the middle 4x6 post. Then, double up the others. Would this be adequate? What type of lumber should I use?

Travis
 

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Discussion Starter #6
Guess I'm going to try double 2x6's, glued and screwed together, with a strip of plywood between them. I'll do that every other 2x6, and see how that works out.

Travis
 

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...the wood is bone dry. It looks like they used some sort of sealant as they laid the shingles down (not just the sealant strip on the single itself). Also, it hasn't rained here in over a month, so things are nice and crispy.
Check it after a good rain and see if it is still dry. If it sagged after getting wet, it won't go back after it dries. A continuous bead of sealant across the shingles prevents any moisture that may get underneath from escaping.

The roof sags all the way across.. The rake is the portion that hangs over past the header, right? If so, that is fine. It's only 12" or so.
The rakes run from the house to the header-the slanted part on the sides. What you describe is the eave--the lowest part of the roof. So the rakes are sagging too?

I thought about using (3) 2x6's in the center, glued/screwed together, where it rests directly on the middle 4x6 post. Then, double up the others. Would this be adequate? What type of lumber should I use?
One would think 2x6 rafters would be adequate across a 12.5 foot span supporting nothing but a roof. Shingling a 1/12 pitch, on the other hand, is a fool's errand. Sistering the rafters would certainly not hurt anything, check the new rafters for a crown and put the proud side up. If there is another reason it's sagging, that is not addressed, it will probably sag again in a few years. Just my opinion.

Post some pics of the rakes, eave, underside and top--perhaps someone here can see what's going on.
 

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Discussion Starter #8 (Edited)
Thanks for the advice..

I'll put a pair of water hoses/sprinklers up there today, and hit it for an hour or so. I've checked it before though, after a good/heavy rain, and the plywood is bone dry. The underside isn't closed in, so it's easy to see/get to.

If it IS getting moisture under the shingles, and I decide to remove them. What's the best/lightest thing I can put up there to cover the plywood, that doesn't look like crap?

The rakes are sagging as well.. but, not quite as much, because the 2x6's are doubled up on the outer posts, so it's beefier there. They might be sagging 1/4" or so.. which should be acceptable, right?

Thanks again..

Travis
 

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Discussion Starter #10
Yeah, but ALL of them? lol..

I'll take some pics tomorrow. I went to Home Depot today, and got some 2x6's, plywood, and Liquid Nails, so I can make a few beams.
 

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15/32" 3 ply ..I'd say that's to thin for 1/12' slope ...especially because you would want to cover that up with a torch down ...right ? Shingles are out of the question ...gotta be min of 2/12 slope for the shingles.

It's sagging beacuse they used PT lumber ..they probably framed it when was wet...so it settled down ..It never goes up.
 

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Discussion Starter #14
I hit it with sprinklers for 2 hours yesterday.. It's was bone dry. I even went as far as to spray a heavy stream of water in one spot (right at a plywood seam), from a foot away, for about a minute straight, and it didn't leak. Even if it DID leak past the shingles, how would it get past the tar paper?

The wood is pressure treated, as I stated in my first post. It is number 2 choice PT pine. I'm not sure if it was wet when they framed it or not.

Tearing it apart isn't an option. I WILL make it go back straight, whether that requires the use of laminated beams, or steel I-beams. One way or another, it will straighten out.
 

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Maybe it was built with the sag. Run a string across near where it si attached to the house to see if the sag is present there as well.
 

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Discussion Starter #17
It was hard to get a pic that showed the string that I ran..



If you look at the 3rd rafter, down from the top, you can see the string. It sags about 1 inch in the center across the span.

Travis
 

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" That's not nice".
It wasn’t meant to be and now seeing the picture of what looks to be the rafters toe nailed into the existing fascia it would surprise me even less.

Sistering another 2x6 would help. I’d build a jack wall under the low point to lift the roof. Sister the rafter and remove the wall one rafter at a time as you proceed.
 

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It wasn’t meant to be and now seeing the picture of what looks to be the rafters toe nailed into the existing fascia it would surprise me even less.

Sistering another 2x6 would help. I’d build a jack wall under the low point to lift the roof. Sister the rafter and remove the wall one rafter at a time as you proceed.
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