roofing problem??

[qwerty2001ro]

Hi guys,

I live in Toronto (cold winter climate) and I own this house built in 2004. It is a semi-detached house. I did not notice this when I bought it in 2006 but I noticed about 1 year later that the roof has this "wave" right in the center over the line that separates the two houses (semi-detached house). (see picture)



I checked the attic for leaks, moisture, but everything seems to be fine.

So, what could be the problem ?
Do I need to repair it? The roof is faily new (6 years old) and since I lived here for 3 winters already ... I don't see any issues not repairing it. Unless it might create other problems.

My neighbor says the house was always like this (he bought his half from the builder).

[wayne soper]

Go up in the attic and take some pictures of the framing. All directions with wide angle.
Then do the four sides of the house at the exterior, wide angle.
Report back when you are done and we can give you answers.
We know what to expect, but your pictures will enforce what we all know is going on there.

[chris mcintyre]

I don't think it is a problem. The reason you didn't notice it for a year is because it's not that bad, it takes the perfect angle of the sun to create the shadows is the picture. I see three very long shadows on the left that appear to be coming from the cap on the hip and I don't see any pieces of cap sticking straight up.

It is the same as taking a halogen light, holding it against any wall or ceiling in any house and seeing that perfectly flat wall look like the surface of the moon :).

[Jerry Peck]

It is a semi-detached house.


Actually, ;) it is quite attached.

In the photo you posted it appears to be attached all the way down the middle (at least one full side).

It is an 'attached' house whether or not it is attached on one, two, three sides are even one small portion.

I can't tell how bad it is because of the great angle the sun is across the roof, but the roof sheathing on your side of the common wall is offset from the roof sheathing on the other side of that wall. IF this offset was down smoothly with a metal flashing there may not be much to be concerned with, however, if there is an abrupt ridge running down there then there is the very real potential that the underlayment may tear, even the shingles may tear along that ridge if that ridge is sharp enough and great enough. Simply covering over that offset with a 16" wide metal valley flashing would (should) keep the underlayment and shingles from tearing. That would leave the final problem of lateral water flow (water flowing across the shingles instead of down the shingles) and shingles are not designed or intended for lateral water flow.

[Dom D'Agostino]

Actually, ;) it is quite attached.

In the photo you posted it appears to be attached all the way down the middle (at least one full side).

It is an 'attached' house whether or not it is attached on one, two, three sides are even one small portion.



Semi-detached is a colloquial term in Canada for duplex.