My house roof has an ell and so there two valleys. The roofing material is what they call "lawn coo" ( sheets of cement type material, 2x4 feet).

There is sufficiant flashing under the roofing, but leaves build up between the flashing and roofing sheets, then the rain water backs up under the flashing and leaks into the house.

I have been cleaning the leaves out, but Im getting too old to climb up on the roof, so Id like to fix it once and for all.

Ive noticed some houses have put cement in the valleys. Im not sure if this would work. The roofing sheets are not tight in the valleys, they are about 2 inches apart, and I think if I fill that space with cement, the water could still back up as there would be nowhere for the water to go.( Im sure some water will leak under the cement. It wouldnt be water tight.)

I may not have explained everything very well, but has anyone has similar problems?

Tom Salarak Khon Kaen

Trim those trees so that the leaves are at least 2m from the edges of the roof.

I had the same problem at a rental house and that was part of the reason I've decided not to have any trees close to the house I built. The rental house had the smaller cement tiles rather than the fiber cement sheet tiling you have. They were cut so that the edges nearly butted together in the valley. It looked nice but that meant it was easy for the leaves and tree debris to get stuck in the flashing underneath. If yours is cut the same, and the flashing is wide enough, you can try having a roofer widen the opening by trimming back the roof tiles to leave a wider gap and help the flashing be self cleaning during the heavy rains.

And, with a wider gap, you may be able to use a long pole from ground level to clean the flashing if something does get stuck up there.

I had the same problem at a rental house and that was part of the reason I've decided not to have any trees close to the house I built. The rental house had the smaller cement tiles rather than the fiber cement sheet tiling you have. They were cut so that the edges nearly butted together in the valley. It looked nice but that meant it was easy for the leaves and tree debris to get stuck in the flashing underneath. If yours is cut the same, and the flashing is wide enough, you can try having a roofer widen the opening by trimming back the roof tiles to leave a wider gap and help the flashing be self cleaning during the heavy rains.

And, with a wider gap, you may be able to use a long pole from ground level to clean the flashing if something does get stuck up there.

An advice given to me by a landscape designer - if trees are desirable, but their falling leaves are a pain to upkeep, select trees with large leaves like palms and midget coconut.

And these are the kind of trees commonly seen around swimming pools.

When trees hang over the roof your chances of various roof water clogage/leakage problems will be high (preaching to the choir I know). When I was growing up, our house had quite a few large maple trees around it and although the limbs didn't hangover the roof too much, the trees were just too close to the house and tall enough for their falling leaves to frequently clog up the gutters, downspouts, valleys, etc. Problems with the valleys was not a huge problem due to their design, but occasionally some large trig/leaf damns had to be removed from the valleys. Although gutter screen guards helped in keeping most of the trigs/leaves out of the gutters/downspouts, we still had clogage/leakage periodically. Well, that home I grew up in is still in the family, and owned by my sister. She has basically cut down the offending trees years ago, planted new ones farther away from the house which don't grow as large, and she now rarely, rarely has any roof issues (still the same roof).

If you don't want to trim the trees back, maybe some screen guards will lessen the problem. I've even seen the screen guards put in roof valleys like the type you have...it won't permanently fix your problem but it should extend the time period between having to climb on the roof to clean things out. I like lots of trees on a residence but you can't plant them just anywhere without causing problems.

fremmel,

My thoughts are just the oposite of yours. My roof tiles have a space (2-3 inches) and the leaves get caught up between the tiles and the flashing. I thought if the tiles were butted up tight, the leaves would just wash down the valley with the rain. Ive looked around at other houses and dont see leaf build-up on roofs where the tiles ar butted.

As for the trees, I have lots of tall shade trees, but they ar 6-8 meters away. I think even if trees were 20 meters away they would still be a problem. We get terrible wind storms here and small tornadoes that carry leaves and other debris hundreds of meters!

I think i will build a bridge across the valleys with cement and seal it as best I can. That way, the valleys will still be open, but the leaves wont get in.

Dont know if it will work, but it will give me something to do.

Thanks, Tom