Anyone here know anything about roofs?

[m35603]

I have noticed something very weird about my neighbor's roof: there is a large rectangular area on her roof that is wet most of the time. I took pictures of it and showed it to her, but neither me nor her can figure out what could be causing it. If anyone here knows anything about roofing, please take a look at these pictures and see if you can figure out what the problem might be.

The neighbor's bathroom is pretty much right there were this wet spot is. Her ceiling in this bathroom is vaulted. We were thinking it could be condensation, but if it in fact is, will this constant moisture not damage the roof over time?

Pictures numer 1 and 2 were taken on a cold morning at 7:30, the area that is wet shows frost on the roof, while the rest of the roof is pretty much frost-free. The other pictures were taken two days before the frost ones, also at 7:30 in the morning, but it wasn't as cold that night so the roof is only wet in this one spot. The rest of the roof is dry. Also, the dark lines that you can see on the roof are always there, even when the spot on the roof is not wet.

This is a house that was built 6 years ago. And, in case it matters, we are in North Alabama.

Any input would be appreciated!

Angie

[Todd H.]

What's the structure in the house under that area? Cathedral ceiling or anything interesting? Is there a bathroom under it that might be venting into the attic plenum? (though I seriously doubt that would cause that).

I had an issue on a home I purahsed that had one section of roof that looked quite different from the rest. Closer inspection showed a lot of microcracks on those shingles. They were lighter in color than the rest. Best explanation the pros who looked at it thought was "perhaps one bad package of shingles for some reason."

Dark staining on shingles can be from teh mildewicide breaking down, at least that's what I've heard a few times. Perhaps one batch of original builder shingles that had a manufacturing problem with the mildewicide.

These are all guesses but perhaps some ideas to explore.

Best Regards,

-- Todd H.

[Tom G]

= Here's my theory. The shadows indicate that it is on the West or Northwest side of the house. A cold roof like the surface of bridges will develop frost before a warm roof. This area of the roof, being over a cathedral ceiling hopefully would be well insulated from the warmth of the bathroom below. Thus the roofing material would get cold at night and condensate moisture out of the air as the air warmed up...like your glasses steam up when you walk into a warm room from outside. The rest of the roof is exposed to an attic which should be better vented and would allow the roof to warm up from below as the outside temp rose. It should be the same temp below and above and might not condense water out of the atmosphere while the wet section would not warm up until the Sun got to it. Here in Northern Illinois, roofs on the North side of a house usually show frost in the morning, until the Sun gets high in the sky and warms the North exposure. I would suspect the permanent dark lines are possibly due to mildew growing in the moisture.

Tom G.

[DK]

It is most definitely a lack of proper ventilaton in the attic beneath the noted shingles.

And it obviously has already damaged the roof. Instead of the normal lifespan, you can expect failure about 10 years early.

Fixing the problem should be fairly simple. You just need to ventilate that section of the attic. Permament fans should do the trick.

Duffaukid

[J.A. Michel]

Looks like it's already damaged to me. Looks like the sheeting under the shingles is damaged. The fix could be costly. It could be water vapor is condensing in the roof, especially since you mentioned that it's above a bathroom. The job might be best left to a pro. If there is a problem with mositure, best to address it NOW. Where there's moisture, there's mold.

[Malcolm Hoar]

I would get a report from a qualified/licensed roofing inspector. Also, clue up on local codes, laws and customs. Then formally send pertinent information to the builder and ask them to correct the problem. Maybe the builder will respond positively. If not, get estimates for remediation and then decide whether or not to bite the bullet and self-fund the repairs or, hire an attorney and pursue a legal claim against the builder.

[Steve Barker LT]

did you READ the original question?????

[Todd H.]

Yeah, I missed the paragraph describing what's under the area. I'm happy to offer the original poster a full refund.

-- Todd H.

[trader4]

There's some things here that don't make sense. The first is, I can see how a section of roof can be wet or covered with frost at 7:30AM in the winter from dew. But I don't see how it can be wet "most of the time." Are you saying it doesn't just dry off in a couple hours on a clear day?

If it does dry off in a couple hours, I'd be curious about what's going on in the rest of the roof, that has an attic. Is that roof area also covered with dew, but it dissapears a lot more quickly? If that's the case, it could indicate that the attic area is not well insulated, or has hot air leakage from the house, leading it to be warmer. That leads to the attic area drying off faster than the better insulated cathedral section.

The other possibility would seem to be that the cathedral ceiling area is in big trouble. If the insulation in that area is water logged, it would seem that the whole thing could chill down overnight and then remain cold for a long time the next day. That could be what you are seeing. This could happen if the cathedral ceiling is not properly vented. There should be soffit vents and then someplace for the air to go at the top of the cathedral ceiling. Typically this would be a ridge vent, but in this case seems that the cathedral bath ceiling doesn't go all the way to the peak. What happens in the attic where it terminates? Is it open so the air can continue on into the main attic, or did they block it off. Also, they should have used baffles in the cathedral ceiling to provide an air channel and to make sure insulation doesn't cover the soffits.

I'd get a good, qualified home inspector to do an insepction of the whole house.

[m35603]

Yes, when it is wet, it does dry off in a couple of hours, but it is wet even when the rest of the roof is not wet. I usually go outside at

7:30 in the morning to let the dog out, and it is wet on most mornings, not all of them though. And the wetness can't have anything to do with rain, because this spot is wet even when it hasn't rained in days. It appears to dry during the day (except for the dark spots), but the next morning it's there again.

When it's cold, you can see a little bit of frost on the rest of the roof, but a very obvious layer of frost in this one area. After a while (as the temperature goes up), the rest of the roof will be frost-free, while this one spot still has the frost on it. It does go away after a while though. When the spot is "only" wet, not frozen, I have never noticed that any other areas of the roof are wet also, only this one spot.

Sheesh, I'm glad it's my neighbor's roof and not mine. This whole thing sounds like it might quite possibly be a serious problem.

I appreciate everybody's input here -- very interesting opinions! If my neighbor does have a professional come out and look at her roof (I will suggest it to her), I will let you all know what his opinion is.

Thanks again, Angie