Roof leaks

[mike4230]

I have been living in my house for about 18 months now and never had a problem with the roof. The roof is about 5 years old, and laid over the old roof. I had done a visual inspection back at the end of the summer and it looked great, not a sign of wear yet.

Problem started last week when we had about an inch of snow, followed by sleet and heavy freezing rain and eventually heavy rain. I developed a leak in the center of the roof. It is not near anything that exits the roof (chimmney, vents ect) which is what is really puzzling. It is also about 8' up from the edge.

My diagnosis is that ice damming caused the water to back up under the roof. I find it hard to believe because I thought this only occurred at or near the gutters (gutters fill with ice/snow and prevent water from leaving the roof and back up under shingles) and was much less likely to happen on an asphalt roof vs. a cedar roof. It rained heavily sun-mon and nothing leaked. My question is, is it possible to get ice dams this high on the roof? If it wasnt that then what caused the leak. Thanks for the help.

[Fischer]

The scenario is:

Snow accumulation.

Freeze.

Water Dam.

Roof over.

Water backup to any low spot thats perforated by a nail or staple, including the water line or the shingle tab itself.

This can happen with a moss accululation at the end of the roof tab. Water can be prevented from running down the roof just enough to sneak in that hole caused by the fastener. This is exacerbated with a roof over because a nail may go just at the edge of a tab of the old roof.

Go up to the roof and lift of the tabs and see if there's any wet spots under the shingles or look for nails in the water lines, or the joints between the architectural shingles.

[Mr T]

depends on the pitch.. Low pitch roofs can ice dam in more places then high pitch.
Any drain vents nearby? How bout ridge vents? If you had enough wind driven rain and cheap vents, you could get water blown up in them.. Ive had it happen before.

Look in the attic for signs of water. If you are looking for a cause based on ceiling damage it will rarely be near where the spot is. It could be coming in down low and running in your attic.

On a sunny day go up in the attic and look for signs of daylight. Look from several angles.

Check with your roof installer on their labor warranty.

[mike4230]

Fishcer: I plan on getting up there this weekend granted that there is not any snow...to sum up what you said and so I understand it a little better, your saying to lift up a couple shingles and see if they are nailed near the exposed part of the shingle or in the groove between shingles?

Mr T: The roof is pitched pretty good. I would say the ridge is 8-9' above the floor. The area that it leaked is above all vents (bathroom and main stack) by about 3-4'. There are no ridge vents or soffit vents (planning on putting them in in the spring).

Thanks for the help so far, I think its a matter or getting up there and checking things out again. Anything else to look for?

[Fischer]

Look for any dips in the way the shingles lie down. Sometimes they kind of cup. Chances are that there won't be any water left, and that explains why it only happens when there is snow up there. Snow dams the water, just enough to create a little pool for the water to back up into a penetration. As it continues to rain or melt, the pool remains and will find a place to leak until it gets to a lower level of water.

Again look in the water lines if you have a 3 tab roof.

I've run across this many times. Sometimes when you have an OSB roof and the edges of the sheathing swell, it's enough to do the same thing. Either you wait for the rain, or put a hose up around the leak for awhile and then flip up the shingles to see if there's any pools of water underneath.

[softdome]

The one thing you don't say is where you live a lot can be determined by the climate zone. Also venting a roof is good in some zones and bad in others. also the type of insulation and where it is located. Being the damage is above bath room vents leads me to believe they are vented to the attic space and the problem may be from the underside of the roof with water vapor condensing and freezing. Venting to the attic is not never good.