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strange Roof leak

63dot

63dot

macrumors 603
Original poster
Jun 12, 2006
5,269
339
norcal
I live in a standard house with a slanted roof, vs. the flat roofed, leaky place I used to be in.

For many years, there are almost no leaks in this '50s built house, but when it rains, and the wind blows from a certain direction only, I get a few drops of a leak and then I won't see it again for a year or more. It's only on north side of the house and I am on the West coast of the USA.

What could be causing this?

One roofer said this is common and happens to slanted roofs even when they are brand new.
 
Leaks should not just happen and be "common". Leaks are caused by poor workmanship or bad materials. that being said, the next time it rains, and you get this leak, go up into the attic and see what is. The insulation should be damp over the leak so look up. You'll see the source. If not, pull it up and see if it's wet under the insulation. If not, then it's probably not the roof. It could be the siding/brick or whatever is facing your house. It could be blowing up from under the eves/facia. If the leak is near a window, it could be poor sealing. Water can get in almost anywhere if you let it. Without more info from you, I couldn't hazard a guess.

Find someone else to inspect rather than that guy.
 
MultiM said:
Leaks should not just happen and be "common". Leaks are caused by poor workmanship or bad materials. that being said, the next time it rains, and you get this leak, go up into the attic and see what is. The insulation should be damp over the leak so look up. You'll see the source. If not, pull it up and see if it's wet under the insulation. If not, then it's probably not the roof. It could be the siding/brick or whatever is facing your house. It could be blowing up from under the eves/facia. If the leak is near a window, it could be poor sealing. Water can get in almost anywhere if you let it. Without more info from you, I couldn't hazard a guess.

Find someone else to inspect rather than that guy.
Click to expand...

Thanks for the info.

Come to think of it, that guy belongs to the biggest, and really the only roofing company that isn't a family business with a few workers, so his motivation is to redo my whole roof. They do the roofs of all the schools, churches, government buildings and they think big and fast.

Too many around here have claimed their work is bad, and they remind me of the Wal-Mart of roofing businesses in my county. I could see how "thier" work would have common issues with leaks right after they put a roof in. He also told me they have "redos" since it's a very tricky thing to put in a roof that can keep "all" water out. Either he is telling the truth or he is a master salesman from a very large company. ;)

When I get that leak again, whether this year or three years from now, I will have to go up into the attic and find the source. It only lasts for a few minutes and I will have to get to the source before it dries. I don't look forward to it, but it's the only way I will find this very intermittent and elusive source.
 
I live on the east coast and here we get lots of rain and having a foot or more of snow on your slanted roof isn't uncommon in the winter. Your roof should be plywood bottom, then a waterproof liner, and then a final layer of shingles. The previous writer was correct... your roof should not leak ever.

Besides waiting for the next heavy rain. Could you try using a garden hose to simulate the rain coming in from the side you think is causing the leaks. You could have a friend use the hose while you go up into the attic and see where the leak is coming from. This way you could do it in the daylight, on a nice day... when it is convenient for you.
 
I had the same problem when I brought my house. During a thunderstorm, sometimes it would leak, most of the times not. It had be baffled, for a weeks until I paid attention to the wind direction. I leaked only with a stiff north wind. I climbed onto the roof and discovered that the whole shingle above the leaking area was loose.:eek: When the wind blows hard enough to lift the shingle, rain water gets driven into the gap.
Piss poor workmanship, no doubt. The nailing pattern was a dead giveaway as well as the uneven spacing of the shingles (the rows would vary from 5.5" to 6.5":eek::eek::eek:) I applied some roofing cement to hold down the loose shingle temporarily until I could replace the roof.
There's a good chance the OP's roof has the same problem.
 
My only thinking on how it happens is slanted roof use the shingles overlaying each other and when the wind blows the right direct it can start shoving water up the slop of the roof and there for under the shingles. The flatter your slop roof is the greater the chance of this happening.

That being said it should not leak. Wind can damage a shingle and cause it to lift and allow water to get under it.

Some one else explain how a shingled roof works. Leaking is a problem with wind is a common problem but still a problem and is not acceptable.
 
Mousse said:
I leaked only with a stiff north wind.
Click to expand...

It's that stiff north wind, or northeast if I am gauging the wind right. The south winds and west winds last night did nothing.

And not just a stiff North or NE wind, but something exceedding 50 or 60 mph. Short of that, there's no leak.

I can't replicate this condition with a hose so I will have to go up in the attic pronto when and if we get one of those northeastern storms and heavy wind. Knowing my luck there will be no leak and I will have to wait until next winter.

The roofer said with the right wind, the capillary action could eventually bring water into a small hole, have their be a few ounces of water getting through, and then force that 1/2 ounce of water getting into the house. It's not a lot of water but it's where I keep my computer and guitars so it really bugs me.
 
.....or you could go up onto the roof and inspect the shingles around where the leak is. Just remember to cover a fairly large are because water can travel from where it enters.
 
MultiM said:
.....or you could go up onto the roof and inspect the shingles around where the leak is. Just remember to cover a fairly large are because water can travel from where it enters.
Click to expand...

The shingles look good everywhere. I suspect a minor leak coming from a small hole nearby under the shingles and tarp. I won't rule out water leaking in through a small fissure high in the north facing wall. Even though this leak has its dry water marks on the ceiling that go back until at least the late 80s from when it was a rental, it's the most elusive thing.

The obvious is easy to detect, fix, and get over. This won't be obvious and we may call over a specialized carpenter who does fixes for roofs after busy roofing companies miss an area.

Where I live, the building codes only require minimum flashing and tar and tarp around a brick chimney. He comes in and heavily tars the area and puts bigger flashing on and has repaired many weaknesses in that area of roofs in neighborhood homes. We will call him over to fix these issues.

When we had a fence which experienced rotting after just 7 years, we called him in and he fixed it. The original contractors used redwood and it held up OK, but our guy uses treated construction heart redwood, and that fence is still close to new 11 years later.
 
Rodimus Prime said:
Some one else explain how a shingled roof works. Leaking is a problem with wind is a common problem but still a problem and is not acceptable.
Click to expand...

You will never have leaks with a well roofed house. The base wood material is covered with tar paper which is overlapped over the entire roof, this is nailed down in the overlapped positions to ensure that you have 2 sheets of protection where the nails go through to secure the paper. On top of that you place a starter strip at the base and then caulk the nail holes, then layer your roofing shingles in tiers so that the next shingle up always covers the holes the nails create, and then a roofcap is put at the top to make sure no water can get through those nail spots, the last of the roof caps have an exposed nail which is caulked over.

There really isn't any reason water should get under your roof unless the shingles are just poorly done.
 
MacNut said:
Shingles are supposed to last 15-30 years.
Click to expand...

little high there. Asphalt shingles are designed for around 10 years. 15 years is the upper limits of the design.

Asphalt shingles are typically is what is used on homes today. They are the cheapest per year to use.
 
I know in hurricane areas everyone has to use 140+ mph shingles. I think they are rated higher. All new roofs have to be architectural shingles here.
 
Excellent suggestions

I had problems with flashing as well, so check that too.

sek

MultiM said:
Leaks should not just happen and be "common". Leaks are caused by poor workmanship or bad materials. that being said, the next time it rains, and you get this leak, go up into the attic and see what is. The insulation should be damp over the leak so look up. You'll see the source. If not, pull it up and see if it's wet under the insulation. If not, then it's probably not the roof. It could be the siding/brick or whatever is facing your house. It could be blowing up from under the eves/facia. If the leak is near a window, it could be poor sealing. Water can get in almost anywhere if you let it. Without more info from you, I couldn't hazard a guess.

Find someone else to inspect rather than that guy.
Click to expand...
 
Rodimus Prime said:
little high there. Asphalt shingles are designed for around 10 years. 15 years is the upper limits of the design.
Click to expand...

You're a little low. From http://www.roofhelp.com/choices/asphaltshingles/

The lifespan of asphalt shingles depends highly upon the environment. Shingles in cooler climates such as the northern United States seem to last longer than those installed in the warmer climates. Studies have shown that the average lifespan for a 20 year shingle in Phoenix, Arizona is around 14 years. In Minneapolis, Minnesota the lifespan was 19.5 years. And in Reading, Pennsylvania, the lifespan was 20.8 years. From this data it seems obvious that the hotter the environment is, the shorter the service life of the shingles. One thing that's very damaging to shingles is Thermal Shock. Thermal Shock is what roofing materials experience when the ambient temperature changes dramatically within a very short period of time - usually 24 hours. For example, in Yreka, California, the temperatures during a summer day can often reach 100 degrees and at night, they'll often drop below 50, sometimes as low as 40. Roofing materials are unable to expand and contract to accommodate such a dramatic temperature change in such a short period of time so cracks and splits in the materials start occurring. Water can then enter the materials and damage them further in two ways. One is the damage water does to asphalt materials in general. It's not that water hurts asphalt, but algae and fungus do and the continuous presence of water will permit algae and fungus to grow on asphalt materials. Another way water damages is the freeze-thaw cycle. In the cold months, water will get into the cracks and then freeze at night. Water expands as it freezes so the more this occurs, the bigger the cracks or splits become. This is why most roofing contractors and consultants are such big advocates of sloped roofs. The better the roof sheds water, the less problems it will usually experience.
Click to expand...

Many shingle manufacturers advertise a 25-year warranty. From the data above, perhaps the optimism is unwarranted.
 
Those plastic, or as they call it asphalt tiles, are meant to last what?...10 to 15, or even 20 years?

They are ugly and unfortunately, I have them.

On ABC news radio, there was a topic on human made trash and how to address this growing problem from computers that were too old, to carbon emissions, to roof tiles. Researchers at MIT found these tiles, which were engineered to last "longer" than a wood tile, lasting in the 50-100 year range. There was no easy way to dispose of these, and like styrafoam, we have this indestructible product that takes too long to break down.

The upside is that you won't get leaks, or if you do it will be some anomaly which I now have narrowed down to water blowing in a hard north rain into the paneling a foot and a half above the windows where there is a 1/16" inch gap between the wood and the stucco on the outside.

The downside, besides being ugly, is that if thrown into a landfill, they will take far too long to break down.
 
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