Leak on flat roof.

20 years ago

Hi folks,

I've got an upper deck, that is over a media room I'm remodeling. With heavy rains we had over the weekend, I discovered that there is a leak on the deck.

From what I can see, it appears that the flashing is completely adhered to the full length "bench" that it's attached to. In the link below you can see the picture.

As you can see, the deck has R-channel sheet medal covering the flat portions (which will soon be covered by ipe decking), with flashing.

The leak is about even with the window, between the flashing and the "bench".

What I'm contemplating is extending the flashing over to the top of the bench, then sealing either the whole deck (about 14x19) or just the seams with some type of liquid rubber sealant.

I'd like to get advice on whether this is a good idea, and to solicit any other thoughts.

Thanks!

Here is a link that might be useful: {{!gwi}}

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Comments (4)

sdello
20 years ago
"adhering" the upturned leg of the flashing at the "bench" is a poor detail in my opinion. It looks like you have a single ply ruuber roofing membrane over the bench. This membrane should be turned up under the siding at the house and continue over the bench and over the upturned leg of the flashing at the flat section.

Does the flat portion have any slope?
Where is the water collected under the decking going to go?
What about deteriorated leaves and other debris that may impede water flow across a shallow pitch, under the decking, or are you going to add some stone ballast to help flow?

I hope the ceiling joists are of sufficient stiffness to handle the liveloads/snow loads/ etc. from the roof top deck usage without sagging.

Sealant as a water barrier are a temporary solution at best. The sealant will degrade and crack with time.

Make sure side laps are wide ~3-6 in., well adhered, and lapped sloping to the drainage. These residential flat roof decks are notorious for leaking.

Good luck with yours and hope this helps.
odln018
Original Author
20 years ago
I believe what's happened is that where the membrane goes under the metal roofing, there's a break in it. I've got to pull up the corrugated metal, and seal this break somehow. The membrane does go across the entire length of the deck, and up under the siding.

There's a slope to both the deck, and the bench, emptying into a gutter.

I was planning on simply putting decking on top of the metal.

The joists are 2x12. Fortunately, there's relatively little snow that accumulates (Arlington, TX).

I was thinking I should also put sheet metal down, and extend that up and under the siding as well, but I'm wondering if it might not be better just to get another piece of membrane and replace the bench area where it meets the deck.
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pew1
20 years ago
Don't get too focused on where the leak is entering the house. The problem could be afar.

Paul
odln018
Original Author
20 years ago
Agreed, I do believe I have the area pinned down, during our latest Texas deluge, I went up to the deck and place plastic over the suspect area, and that seemed to stop it.

I'll pull the metal up and see what else I can find.

Someone also recommended to me to use that elastrometric sealant, but I'm fearful that is a short-term solution, as was mentioned previously:

Here is a link that might be useful: Sealant