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Dragon 01-09-2009 11:25 AM

Strange Winter Roof Leak
1 Attachment(s)
Of course this happened on the day my family was coming over to celebrate Christmas with us. While cooking the meal prior to their arrival water started dripping down out of the exhaust hood above our gas cook top. A pretty steady dripping of water that was not quite a continuous drizzle. This occurred just before noon.

The weather conditions were that we had just gotten a bunch of snow earlier in the week but it had all pretty much melted the day before and it had been lightly raining off and on that morning. Going outside to look at the roof showed the roof completely clear of all snow & ice. All you could see were wet shingles. No damage was visible.

I then went up into the attic to see what I could find about what was happening. Crawling through the roof trusses while trying to not compact the blown in insulation was a challenge. I made it over to the area where the water was coming through into the kitchen and found that while the water was coming down through the exhaust hood that the duct work and exhaust fan were not where the water was coming through the roof itself.

The water was coming right through the plywood where there was a nail penetration. This was then dripping straight down into teh insulation and onto the top of the ceiling right where the hood duct penetrates into the kitchen below. I brought up a bucket and placed it under the leak to catch the water. It dripped for a couple of more hours and then stopped. All together I collected about a gallon of water & then it stopped and no further water came through. (The Hood vent has a remote blower unit that is mounted on the roof.)

House/roof info: The house is only a year old. 50 year shingles on the roof laid over ½ inch plywood. Soffit/Ridge venting. Blown in insulation R50 or better. There are two rows of the rubber ice dam membrane protecting the bottom 6ft of the roof line. House located in South East Wisconsin.

The leak occurred above the line where the ice dam rubber membrane is affixed to the roof right in the middle of a sheet of plywood. Attached is a picture of the leak as it was occurring. The water is coming through from the uppermost nail penetration and then running down a couple of inches till it hits the lower nail and then running down that nail to drip into the house.

My thoughts are that this leak occurred due to some kind of freak mini ice dam under the shingles. Water must have become trapped under the shingles and dripped in until it was a gone or the dam finally melted through and the water went down the roof to the gutter. What is strange is that there was no visible ice or snow on the roof when this happened. Anyone experienced something like this? There have also never been any typical ice dams occurring anywhere else on this roof, no icicles etc. either last year or this year.

It has rained lightly once since then and no water appeared to come though. Snowing today so I’ll get another chance to see if this was a one time fluke or not.

I am thinking as a preventative measure I want to thicken up the insulation in that area to prevent any heat coming up out of the kitchen and off the duct work of the Hood exhaust from getting to the roof in that area. Although if this is the case I don’t know why this wasn’t an issue last winter. I also want to get up on the roof and inspect that area closely for damage but that will have to wait for now due to the snow.

My luck in this situation is that it occurred right above the hood exhaust so the water was noticed immediately. Otherwise the water would have done damage to the ceiling drywall. The leak location also leads me to suspect heat leakage from the hood vent area may be the issue. But the hood duct itself is insulated and the majority of the duct is buried under the blown in insulation. ????

What do you all think? Any additional guidance or input on action I should take would be appreciated?

tinner666 01-09-2009 02:48 PM

That 8 or 16cc nail sticking through the deck in the middle of nowhere raises eyebrows. I'll hazard a guess that a nail backed out, or a shingle cracked. Of worse, the nail is in a keyway, or shingle joint.

Michael Thomas 01-09-2009 02:58 PM

I'm curious about two things;

1) The presence of that single nail, and the fishhook pattern of the leak following the adjacent nails.

2) The absence of nail penetrations above that point.

Slyfox 01-09-2009 03:40 PM

With a nail penetrating the decking that much it will suck moisture through even if it's not popped up or in the key way of the shingles and it doe's not require any type of damning either.
Why is it there* beats me, is the roof slope steep?,
maybe it's a poorly placed scaffolding nail?

The temps outside are cold enough for snow,
the temps inside the attic/crawl space are much warmer,
the head of the spike 'freezing' transfers moisture through to the body of the spike 'much warmer' and a syphon effect of moisture occurs.

Pull the spike, place a roofing nail into the hole and dab some roof cement on it, do not use caulking other than roof cement in a tube, other caulking such as silicone will not adhere to the backing of the shingles and will prevent the tab from fully re-sealing.

For the nailing pattern, any 50 yr' shingle I ever installed required a min- of an 1 1/4" fasteners, and with those type of fasteners in that type of decking you should be able to see a clear pattern coming through,
being that you can't I would have to guess they used 1" fasteners and possibly even less fasteners than required by specs.

No way to say anything for sure with out a physical inspection,
one year old home may still be with in the time frame of a warranty,
but even if it's not, if you keep your cool and ask the builder to have their roofer come and check it out more often than not they will.

Dragon 01-13-2009 09:13 AM

Thanks for the feedback.

There is about 10 inches of snow up there now so an exterior rooftop inspection will have to wait for a bit. Although I have walked the roof previously and there were no visible nail heads to be seen. I'll have to look closer once the snow is gone. When it melts I'll have another chance to see if it leaks again. The roof itself is not steep, it is a 5/12 pitch if I recall correctly.

I am going to go up to inspect again inside the attic and I'll take a few more photos of the bottom of the decking when I do. What would you want to see pictures of? The ones included before were pretty close up to get a shot of the leak.

I'll try for a wider view to get a shot of the nail pattern and see if there are any other larger nails coming through. I'll also try for a shot that shows the duct work of the hood fan. in that area.

Let me know what else I should be looking for.

It is 1 year and 9 months since we took posesion of the house. Unless there is some really big problem that affects the entire roof system I do not expect the builder to be very responsive. Their standard comment to any issue raised previously was "That's normal". This left it to me to gather data and do the research and layout proof that what I was saying was an actual issue. Once I did that the response changed to one of grudging acceptance of my position and they addressed the issue. But any issue I did not have hard info on they always tried to brush aside.

Based on what info I have now I expect they would claim that this is an Isolated one time leak due to weather conditions beyond their control and they are not responsible to address it.

Anyways, I appreciate the feedback and assistance in knowing what to look for!

the roofing god 01-15-2009 05:41 AM

definitely smaller roof nails were used ,at 250% magnification ,you can see nail tips there-The larger nail seems driven flush(maybe from a roof bracket?) When the roof is clear ,take pictures of the vent area,and post them

Dragon 01-23-2009 11:39 AM

3 Attachment(s)
I went up to check if there was anymore leaking and take a few more pictures to post here.

There was no water in the bucket I left up there so that's good. But we have not had a long warm thaw yet to see if the leak was going to happen again.

In the first picture you can see the bucket on the left hanging right below where the leak occured. On the low left you can just make out the duct work in the insulation for the Hood vent. The duct comes up through the ceiling right below the bucket, snakes over to the right just out of frame and then turns back to go up and out the roof as seen on right center side.

This hood vent has a roof mounted exterior blower unit, a Broan EB9. What appeared to be a single nail in my first series of pictures is really a bunch of nails surrounding the perimeter of the blower unit.

Were these used to secure the unit or re-attach shingels after the blower was installed? Don't know....

The shingle nails show a regular pattern from the inside of the interior. They penetrate the roof deck about a 1/4 inch, give or take. Close up photo below showing the pattern and the penetration.

The roof is still covered in snow so no exterior inspection yet. I am also going to check to see if I have a photo in my archive from construction showing that area of the roof.

Any comments on the new pics?


the roofing god 01-24-2009 04:06 AM

the inside is only used to mark out the space on the roof that may have problems,unless you show a protrusion leaking,you can`t tell anything from the attic like that

Dragon 02-08-2009 08:24 AM

4 Attachment(s)
Very nice weather this weekend & I was able to get up onto the roof to take a look at things.

A very quick visual inspection does not appear to show any problems like obvious nails or damage to the shingles. Here are some pictures of the area in question. The leak I originally posted on occurred in the area between the skylight and the exterior mounted vent van.

Closer inspection shows bumps in the shingles. Look close; can you see the raised shingles with the slight shadow underneath? Hmmmmmm……

Now what do you think? (Closer pics in the next post)

Dragon 02-08-2009 08:31 AM

4 Attachment(s)
So below are close up photos of the shingles. I lifted up the tabs where you could see a bump in the shingle and this is what I found. The pictures are from four different locations.

The nails are not set flush & it is not just the area in question. The photos in the previous post showing the shadows under the shingle was taken further down from where the leak occurd. I'd guess the bad nails occur every 2-5 feet across the entire roof.

What is your opinion that the raised head allowed the water to penetrate through?

How do these improperly set nails affect my shingle warranty?

As always your feedback & recommendations are greatly appreciated.

the roofing god 02-09-2009 03:36 AM

That`s horrible ,all of those nails will push thru the shingles when they get hot in summer,they also should be inside the double white lines you see,Knock `em all down,and add more where they`re not in the lines,be careful not to put any nails within 6" of the seams

Dragon 02-10-2009 08:53 AM

Seeing that this roof was installed almost 2 years ago what are the odds the builder and or roofing sub would be inclined to come out and address this?

It also appears that this will affect the warranty on the shingles themselves due to improper installation. Should this be the avenue I use to approach the builder with?

For those of you that are GC's & contractors, how would you want to be approached by a former client regarding this & how would you react?

Some searches online indicate that just pounding down the nails is not the best idea. IE hammer damage to the shingles trying to get the nail properly flush, etc.

What can I expect as possible solutions offered buy the builder/sub?


Ed the Roofer 02-11-2009 05:40 PM


Originally Posted by Dragon (Post 228158)
Seeing that this roof was installed almost 2 years ago what are the odds the builder and or roofing sub would be inclined to come out and address this?

It also appears that this will affect the warranty on the shingles themselves due to improper installation. Should this be the avenue I use to approach the builder with?

For those of you that are GC's & contractors, how would you want to be approached by a former client regarding this & how would you react?

Some searches online indicate that just pounding down the nails is not the best idea. IE hammer damage to the shingles trying to get the nail properly flush, etc.

What can I expect as possible solutions offered buy the builder/sub?


The Builder and the New Construction (cough-cough) Roofing Contractor typically only have a One Year Warranty.

But, most people are unaware that the time periiod gets extended for certain issues, which I believe that this would fall under that logic.

You would have to Lift the tabs before nailing the unseated roofing nails flush to the shingle surface.

Lift up a good amount of tabs and see how many tabs are similarly affected and take photos.

You can get that Kids sidewalk chalk, which will wash off, to write numbers on top of the shingles.

Show all of those numbers and affected shingles in a written report to the builder, who did not follow up to see if his roofer did the job per spec.


Dragon 10-09-2009 11:07 AM

An update is overdue on this thread so here it is. Grab a cup as it is lengthy.

After the first leak described in the preceding part of this thread we had another leak. This time the water started coming out of the ceiling fan in our half bath at a pretty steady rate.

I contacted the builder and the response was positive. They made arrangements for the roofing sub-contractor to come out and see what was happening.

The roofer determined that the first leak was being caused by a nail that had backed out that had been installed within an inch of the seam of two adjoining shingles. The roofer caulked the nail hole and it has not leaked since.

The second leak was being caused by improperly installed (i.e. none) flashing at the roof vent of the bathroom vent. The roofer caulked between the roof vent and the shingles and it has not leaked since.

The roofers immediate observation was, “who installed these roof vents?” As to him the quality was sub-par and he could tell that they had not been installed by his crew. In fact the roof was shingled by his crew completely and the install of the roof vents (3 bathroom, 1 dryer and the kitchen hood) was probably done by the plumbers and or HVAC crews after the roof was put on.

Further inspection by the roofer showed very poor flashing on the install of the vents (which was causing the leaks). The roofer said if his crew would have done the installs when the roof went on each vent would have had its own surround of Ice & Water shield etc. which was obviously not there.

That was the leaks, now on to the popped up nails.

The roofer had no concrete explanation for these. He tried to say that it was the fact that plywood was used instead of OSB for the deck and that the plywood was causing the problems with the nails. I called horse-hockey on that as plywood has been around and used for roof decks for quite some time and the reason it has gone out or regular use for roof decks is simply due to cost. The plywood on the roof is ½ inch Exposure rated plywood, not anything chincy.

Then he tried to blame the problems on the ventilation for the roof saying he though there was not enough soffit ventilation. I asked him what he was basing that determination on? Did he do a calculation using the length of the ridge vent, number and sqft of the soffit vents in relation to the overall square footage of the attic space? His reply was “ummm no, I don’t even know how to do that calculation.” I replied with “If you didn’t do that then how can you know what you are claiming about the ventilation is accurate?” His reply “I do a lot of roofs and I think you need more soffit ventilation, if it was my house I would.”

So no determination as to what is causing the problem. The roofer and 3 of his guys then spent a little over an hour on the roof pounding down raised nails and caulking ones that had already poked through the top shingle layer.

As they prepared to leave I asked right to the roofers face “Did you get them all? Referring to the popped nails, his answer “Yes, we got them all.” He also said that they would come out in August to check the roof for anymore pops before winter set in.

I was able to get back up on the roof the following day to check things out. It was obvious that they had not gotten them all. Within seconds of getting onto the roof I was able to spot one after the other backed out nails and nails poking through the top layer. Grrrrrrr…..

I called the builder, emailed photos, The roofer was back a couple days later and they spent a number of additional hours up on the roof. I could not be there then so I don’t know exactly how much time was spent although I do know it was not for the entire day.

I had a baby boy in the mean time and time to monkey around with looking at the roof checking their work fell off the list of things to check on.

So that was in the spring. Summer comes and goes. August comes and goes and I do not hear back from the roofer for the follow up check he said he would come out to do.

I get back up on the roof and it is pretty obvious that there are still nails backed out and there are still nails that have poked though the top layer that have not been addressed.

I contact the builder and outline things to him and ask him if he can have someone from there side come out and look at what is occurring. He does. I meet with one of his project managers and we look at the roof both from the top and from underneath. I had about 15min in the morning to get up on the roof before the meeting and was able to use Ed the Roofers suggestion and marked out a number of areas with sidewalk chalk. That was very helpful in saving time looking around and focusing attention on the problems. The rep did not say much to me as what he thinks is going on other than, “I have a pretty good idea of what is happening. We’ll be in touch”

I’m thinking, Yea! Finally.

I am contacted by the builder. He is going to bring out the roofer, materials supplier, and an independent builder as a Mediator and they all want to look at the roof. He says at some point during the visit I may be asked to leave as they discuss the issues.

They come, they look, they think it is not as bad as they though it was…….. The inspection reveals that the nails used are longer than what was required by CertainTeed for installation. Nail penetration through the roof deck deemed adequate. So at this time they are not going to do anything so drastic and expensive as to re-roof the house, which I had been thinking might be possible.

So the tentative action plan from them is:
- The roofer is going to come back and go row by row on the shingles and pound back in backed out nails and caulk the shingles that have nails that have poked through the top layer of the shingles. The roofer will also remove the improperly installed vents, and flash them properly.
- A moisture & temperature monitor will be installed in the attic and checked this winter and spring to see if there is something going on in the attic.
- Repair the interior drywall damaged by the leaks
- Backfill blown insulation wetted and tramped down in attic

At this time there is no determination as to what caused/is causing the problem with the nails backing out. Will be waiting to see what the moisture & temp meter tells us.

And that is where it stands.

Comments & Feedback?

ShortEdged 10-09-2009 11:47 AM

Can you explain what was wrong with the dryer vent flashing in this pic?
Are the nails that are popping out the extra long ones? If so, they may not have the teeth groves all the way up the nails (slick shafts). If that is the case, can slip up easily and may have been like that since day one from using the nail gun a little to fast or not the right air pressure.

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