# Damaged roof sheathing, looking for suggestions



## mtuozzo (Mar 6, 2017)

Hello all, I'm new to the forums and this is my first post. So please let me know if I violate any forum rules that I missed. I did search to see if a similar thread already exists before starting a new thread but I didn't find one.

I purchased a home July of last year. It is a raised rancher built in 1970. It really is a beautiful home and we are very pleased with it. However, like any home, there are things that need to be done. Fortunately the roof is relatively new so I shouldn't need a new roof for some time. However, there is a roof repair that I feel is necessary and I'm looking for some good approaches to repair it.

In a nutshell, it's obvious to me that when the roof was installed and the last section of sheathing was cut to fit at the edge of the roof, some idiot decided to cut the sheathing laying on top of the second to last section of sheathing with the saw blade too deep. And of course the idiot cut right through that brand new section of sheathing that was just installed. Cut it almost all the way up, not quite center between the two trusses. Why they didn't replace it when they made that mistake is beyond me. There's no way they didn't know it happened. Regardless, we own the house, have no idea who the roofer was and are stuck with. The sheathing overall is in good condition, no rot or deterioration. Just the cut and sag to contend with.

I wouldn't be too worried about it except that there is an obvious sag right where the cut is. There are no leaks, just a sag. My concern is that it's obviously weaker where the cut is or it wouldn't be sagging, and after some aging in years to come and a good enough snowfall someday that section of roof may give way making a real mess. I'm the type that would rather fix it now and avoid the mess.

I'm looking for recommendations on how to reinforce the sheathing at the cut. I'd prefer to avoid removing the shingles and replacing the section of sheathing if possible. I'd also like to avoid any nails or screws through the roof so I don't have to worry about potential leaks. I'd rather structurally reinforce it in the attic using the truss system for bracing. I do realize the "best" or "right" way to fix it is to replace the damaged sheathing. I'm hoping there is an "acceptable" way to reinforce it from the attic that is less invasive than tearing up a section of the roof and replacing it.

I've attempted to attach a picture of the damage from the inside, a picture of the sag from the roof line, and a picture of the truss system visible in the attic. Disregard the comment in the roof truss picture about "Modified and cut truss". The pictures are the home inspector's comments in the home inspection report. The damaged section is not at this modified and cut truss. It is at the far end of the attic in the truss picture. I'm including the truss picture to provide a visual of what I have to work with for bracing and support.


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## Bondo (Dec 8, 2007)

> I'm looking for recommendations on how to reinforce the sheathing at the cut. I'd prefer to avoid removing the shingles and replacing the section of sheathing if possible.


Ayuh,.... What I would do is,....
In the attic, lay a couple 2xs across the ceilin' joists below the cut in the sheathin', givin' ya a work area, 'n something solid to jack off from,...
Cut 4, or 6, 2x4s to fit inside the roof rafters, to bridge the area under the cut in the sheathing,.....
Position a 2x4 across the cut, rafter to rafter, jack it up to where it's supposed to be, then screw or nail the 2x4 in place from the adjoinin' rafter bays, through the rafters,...
Continue til the 2x4s are bracin' the sheathing up where it's supposed to be, go have a cold one, 'n call it a day,....

I'd think a 2x4 per foot of cut through the sheathin' oughta be more than plenty,...


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## Windows on Wash (Aug 30, 2011)

+1

Is the area of impact directly above that whole house fan?


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## craig11152 (Jun 20, 2015)

Bondo has the plan. 

An alternative would be 2 2x4 that run between the trusses. One at the top of the cut, one at the bottom then a 2x4 that runs up the cut sort of like you were framing for a skylight. But Bondo's is easier and will work just fine.


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## mtuozzo (Mar 6, 2017)

Windows on Wash said:


> +1
> 
> Is the area of impact directly above that whole house fan?


Negative. It's over a bedroom with at most a light fixture, insulation and Sheetrock beneath it.


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## mtuozzo (Mar 6, 2017)

Thanks for the input. I was thinking along the same lines, although I wasn't sure if 2x4 would be good enough or if I should go with whatever the trusses are (2x6 or whatever).

I honestly have no idea how I'm gonna jack it up though. That's a tall jack height with no real floor for stable support, a roof pitch angle at the top and changing length as I move up/down the cut. 

What a pain. I still cannot believe someone cut the sheathing like that and just left it. It would've taken them 10 minutes or less to remove and replace it when it happened. Now it's gonna take me hours to deal with it from the attic side. Blows my mind.


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## Bondo (Dec 8, 2007)

> I honestly have no idea how I'm gonna jack it up though.* That's a tall jack height with no real floor for stable support, a roof pitch angle at the top and changing length as I move up/down the cut. *


Ayuh,.... I envision the 2x4s layin' flat against the sheathin',...
With several pieces of 2xs, long enough to catch a couple ceilin' joists, build a bridge to jack off from,...
Stack a pile of wood blockin' on yer bridge high enough to support a jack under the flat 2x4 against the sheathin',....
Jack it up, screw the 2x4 in place, move down the roof, remove some blockin' from under yer jack, 'n repeat,...
It shouldn't take a 'ell of alota jack pressure,...

Nobody said it's _Easy_,....
If it was, everybody would be doin' it,...


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## Yodaman (Mar 9, 2015)

Something doesn't look right. The sag on the top side appears to be more substantial than just the saw cut from the underside. From the underside damage, we should expect the sag to be contained within one rafter bay, or 16 to 24".
Looking at the top, it appears the sag is more like 3, 4 or more feet wide.


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## Gary in WA (Mar 11, 2009)

I agree, that is a deep, long sag....

IMHO, being a framer- Craig's way is far superior to just adding some between truss blocking to carry the end of sheets, fine for top/bottom weakness areas. The plywood strength axis spans across the trusses- not with the trusses, hence original install direction; http://www.pfsteco.com/techtips/pdf/tt_plywooddesigncapacities

A 2x4 block at each end of a 2x4 square-cut rafter would bring the weakened plywood back to end joint full bearing- as the trusses do. Add both blocks a little past the cuts on each end to reach undisturbed wood so you can toe-nail the block forcing it up to flush the bottom edge with the trusses- measure blocks and trusses before starting- may find trusses are 3-5/8" thick, new blocks are 3-1/2". So blocks are now tight to sheathing at trusses (with maybe an 1/8" gap or so) and back nail the blocks at ends through trusses. Then, add the rafter under both cuts and toe0-nail both ends to force the cut sheathing back up where it belongs. If you add one 3" toe-nail and continue hammering (not forcefully- like an auto body man would), the 2x will move upward in small increments, working both ends of rafter one after another in small gains. may want to utility knife the splinters off the areas that bigger splinters won't lay back evenly with pressure. Do not brace off the 2x bottom chord as you could easily end this repair project by fixing a ceiling screw (more likely nail due to age of build) pop after done in attic. 

Gary


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## mtuozzo (Mar 6, 2017)

Reading the recent responses I was thinking it's not that deep and long of a sag. But now that I look at the pictures again I seem to recall the cut sheathing was on the front side of the house, while the roof sag picture is of the back side of the house. I'll have to climb back up in the attic and get a bit of a refresh on the situation just to make sure my recollection is wrong, vs more issues than I realized.

Thanks for all the input!!


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## carpdad (Oct 11, 2010)

I wouldn't try to make the roof deck flat again. Follow the 2x4 plan. Predrill a toe screw hole on both sides and screw it in and screws should press the 2x tight against the deck. It may, in fact, push the warped plywood up and create a hump. I don't see any nails in the plywood. Make sure later date that the shingles are nailed in adequately.


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