# Why Leaking Roof under Dormer / hole in OSB!!!



## MB1 (Dec 13, 2011)

Ok, please hold back the jokes and take it easy on me as I describe my issue...this is my first post  I've heard good things about this group, so here it goes:

I have been getting some discoloration in my living room ceiling starting just below where dormer meets the main roof (a flat, not A framed dormer). I inspected the area of the main roof right under the shingled dormer and found the OSB rotted out. (good fire starter and sawdust) 

The valley is completely shingled where the dormer meets the main roof and there is little slope where the water should be running off from the valley to the main roof.

What I'm not sure is whether the water is coming through the bottom corner under the flashing, or pooling somewhere and coming in under the main roof between the corner of the valley and wall of the dormer (or maybe it doesn't matter?). 

Any suggestions on how to figure this out, so I can identify my problem area before patching the damaged area below? [Being a newbie to roof repair, I'm trying to avoid tearing up more than I need to]

Thank you in advance for any advice!


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## rossfingal (Mar 20, 2011)

Hi!
Posting some pictures would help! 

rossfingal


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## MB1 (Dec 13, 2011)

Thanks. Will get them on Tues, weather permitting.


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## rossfingal (Mar 20, 2011)

Good!


rossfingal


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## titanoman (Nov 27, 2011)

On a dry day take a hose to it and see if that tells you anything.

Sent from a Samsung Galaxy S2


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## Roofmaster417 (Jun 9, 2010)

I have seen the same when a valley isn't laced with the first shingle entering the valley.

If the last piece of step flashing closing the dormer wall is improper.

If the apron that meets the lace is short.

If the laced shingle is too short into the valley.


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## MB1 (Dec 13, 2011)

*Pictures/HELP!!!! Need to patch roof!!!*

Here are the photos of my leaking roof/dormer...ugly ay?  The leak problem is the corner furthest from view. (5 more detailed photos) I appreciate any comments. At this point, I need to patch this up ASAP to prevent leaking given rain is expected on Thursday. Any suggestions on how to do that so I don't get water in the house? (I'm in San Jose, CA) The short term fix need not be pretty given it only needs to be temporary since I will replace the entire roof soon (I will start a separate thread on this. I need input why the roof is failing...My 8 year old shingles have spidering/cracks everywhere except the top 3 rows below the ridge...not sure if that is a venting and/or product issue, as well as overexposed shingle issue per the "professional" roofers that looked at my roof today.

P.S. As you can see, I did not want to pour water on my roof today to locate where the water is coming in given the hole and laminate flooring below.

Thank you all for your help!!!!

-Marcum


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## titanoman (Nov 27, 2011)

What a mess. All that has to be torn off, then woven and flashed properly.


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## joecaption (Nov 30, 2011)

I also see what looks like where that metal looking roof dumps all it's water right up againt the "dormers" fashia. Not a great plan.
Looks like a drunkun salor did the weaving on those shingles.
If they had of been 30 year shingles they may not have leaked because there's no tabs for water to get under every few inches. I would have also used strorm and ice shield in those valleys.


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## MB1 (Dec 13, 2011)

So, short term, how do I "patch" this up until I get my new roof? One roofer today suggested that I just get something like roof leak stopper (rubberized roof patch) and a trowel, and just cover the entire valley and under the dormer (once I put the shingles back, and add some mesh backing to the hole). Do you think that may be a temporary fix for the next 7-30 days?

Thank you!


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## MB1 (Dec 13, 2011)

PS. Joe, I think the metal looking stuff you are referring to is the 1x2 inch pvc drip edge?


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## titanoman (Nov 27, 2011)

MB1 said:


> So, short term, how do I "patch" this up until I get my new roof? One roofer today suggested that I just get something like roof leak stopper (rubberized roof patch) and a trowel, and just cover the entire valley and under the dormer (once I put the shingles back, and add some mesh backing to the hole). Do you think that may be a temporary fix for the next 7-30 days?
> 
> Thank you!


Just keep in mind whatever you put
down is going to have to be ripped back out in 7-30 days.


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## MB1 (Dec 13, 2011)

Titanoman, are you implying that patching the entire dormer area with the goop is going to create a problem for the roofer coming in? Is this stuff going to do the trick, or is there a better approach short term?


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## titanoman (Nov 27, 2011)

MB1 said:


> Titanoman, are you implying that patching the entire dormer area with the goop is going to create a problem for the roofer coming in? Is this stuff going to do the trick, or is there a better approach short term?


I wouldn't do anything to it if you're going to put a new roof on it within a month.


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## MB1 (Dec 13, 2011)

???? There is rain in the forecast and I have a hole in my roof....I have to do something to keep the water out....am I missing your humor somewhere?


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## titanoman (Nov 27, 2011)

MB1 said:


> ???? There is rain in the forecast and I have a hole in my roof....I have to do something to keep the water out....am I missing your humor somewhere?


No humor intended. Has it been leaking for a while? Maybe you can tarp it off for now, securing it with 2x4 nailers.


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## MB1 (Dec 13, 2011)

There hasn't been much rain since I noticed the problem. But now that I've disturbed the area and cleaned out the OSB, it seems fairly exposed. And, I'll be out of town a week over the holiday. Not much comfort with a hole in the roof!


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## titanoman (Nov 27, 2011)

Didn't you say you had a roofer friend? He would know how to lay some plastic, tucking it under shingles where he can, and some stickers where needed (1x or 2x nailers).


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## joecaption (Nov 30, 2011)

http://roofing.owenscorning.com/homeowner/thingsyoushouldknow/needaroof.aspx
If you know what brand and color of shingles your going to have them install then just buy a bundle and slide a few in under the ones you have now.
DO NOT USE THREE TAB SHINGLES AGAIN>


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## justincase123 (Oct 24, 2010)

Looks like a few pieces of step flashing slipped under the edge of the shingles where they meet the fascia and up the fascia board to cover the gap may help some and maybe a roll of flashing tape for any other areas. Still only temporary and may not keep all the water out, but it may help.


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## MB1 (Dec 13, 2011)

Unfortunately, I do not have a roofer friend. Joe, I was going to go with Certainteed's Landmark 30 year product. Is that 3 tab? Ok product? Any reason why you are recommending not going with a 3 tab?

As for sliding shingles under, I think that may work (along with some step flashing with metal shingles along the facia board; however, if water is pooling and getting under the dormer roof, then it will hit the big hole (where the OSB is missing). Even if I shove shingles up there, water will get under them. My thought was to get some metal shingles, caulk the heck out of them on the bottom with Silicone, and shove them up under the dormer where it meets the main roof. Then patch the area with roofing cement and stepping medal shingles down integrated with the stepped metal shingles down below the original (of course as a temporary patch).

My worry is that I will dam the area with the caulk and bring more water in. Which brings me back to applying roof patch to the entire area to keep water from getting in (if that would work), or tarp it


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## justincase123 (Oct 24, 2010)

You may cover the big holes with a roll of regular aluminum flashing which you can get up to about 20" wide or so . You can see if that will work but it will have to be lapped correctly and slipped under shingles so water doesn't run under it, of course that is assuming the old osb will hold a roofing nail to put it on with.


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## tinner666 (Mar 14, 2005)

Not sure what you'll be using to fix that 'mess', but I'll point out one 'oops' and give you one tip.

The 'oops' is that this is a perfect example of why shingles, or anything else for that matter should extend past the drip-edge. What ever you method you use, metal, SBS, or whatever, be sure and extand past that 'valley outlet' at least 4", and hopefully you will have managed to give that exit a little bit of slope. If it's dead level there, it'll leak anyway without heroic efforts.


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## tinner666 (Mar 14, 2005)

The closest similar pic I had was this. This was a roof butted into a wall. The end extends past about 2" from mit's closest contact point in the bottom and the flap of metal is there for the water to follow it and not wick back under the pan.


By heroic efforts, you'd remove enough wood to install a large metal pan under that eave, flashed into the wall of the dormer, and extending well up the roof under the bottom of that 'valley' you have there. Done correctly it would catch any water that wicks back there.

The way it is now, that piece of step flashing under the valley is correct, BUT, the valley by not extending beyond the dripedge is allowing lots of water to run behind it and the fascia. That's why the rotted wood.


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## MB1 (Dec 13, 2011)

Unfortunately, the OSB isn't going to hold a nail in this area around the facia.

Tinner, thanks for the tip although I am not sure I follow it. Are you suggesting that the Dormer Roof get extended out to each side further or narrowed? Also, with regards to your comment on the drip edge, are you saying that the shingles should extend over the drip edge? If so, by how much?

Thank you!


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## rossfingal (Mar 20, 2011)

The crickets/saddles (the two, triangular sections of roof, behind the front of the dormer) are not extended far enough out to the sides of the dormer.
That creates an almost, "flat" area of roof at the bottom of the valleys.
Also, the shingles were not "woven" correctly.

rossfingal


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## MB1 (Dec 13, 2011)

Tinner, ok, thank you for your last comment which clarified this for me. The two installers I have talked to just want to install valley flashing (I think a W piece) that dumps the water beyond this corner (at the facia board/drip.) Is that likely going to work in this situation?


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## tinner666 (Mar 14, 2005)

No 'W' there. It's not all it's cracked up to be. A large sheet 3'x4' of galvalume with the edges hemmed, and cleated in place, after trimming to fit the structure correctly is what I'd use as Plan A. Start shingle around the edges leaving 80% or more exposed.
Plan B would be 3-4 layers, staggered, of SBS mod-bit.
Plan C would be dimensional shingles but that's another plan all together. I'd probably be starting off on Plan C and be at Plan N by time I got that one finished.


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## tinner666 (Mar 14, 2005)

Oh, the Heroic effort with that catch pan underneath would be 'A given' no matter what else I decided to do above it. Plan on doing both sides that way.


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## tinner666 (Mar 14, 2005)

PS, roof cement wouldn't be a part in any of my plans. I have to get to sleep now. Hope that helps clear it up.


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## tinner666 (Mar 14, 2005)

I like an inch and a quarter to 1-1/2". It's very old school and how water was kept from wicking in before the advent of miracle felt. Cut the tabs off 3-tab shingles and install them rightside up so the sealer strip is right at the edge and 6-nail them as low as possible. 
Look closely at the pic and see how far back the water wicked. Also notice the ice stays off the fascia too. It keeps water in the gutters instead of behind them too.


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## justincase123 (Oct 24, 2010)

I will add my personal opinion and tons of years of experience, When you get ready to put a new roof on, unless those dormers are serving you a usefull service, looks like they may be for decoration only, I would loose them, let the roofers throw a few rafters in, sheet over with osb and shingle without those babies, it will save you a ton of headaches and if the city says anything about it, tell them the wind blew them off.


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## MB1 (Dec 13, 2011)

LOL....

Unfortunately, I love those dormers. They give the room a vaulted look and add a lot of light during the day. I've talked to a few others in the neighborhood with the same configuration, and they are not having this issue. Probably just dumb luck as I can see they have similar shingling and flashing details.


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