Our Flat Roof Leaking.....or is it?

[Border Reiver]

We live in a semi-detached house that has a narrow (about 3ft) flat roof running along the front of both houses, above our lounge windows. The flat roof also covers our kitchen and an office at the end of the house and the overall slope is to a gutter at the rear of the house. The rest of the flat roof has a high felted ridge around it.
I've recently noticed some damp marks in the ceiling part above our lounge window and high up on the wall between us and next door. This becomes quite damp when it rains (but it never drips) and dries completely when the rain stops.
Over the last few years I have used rubberised paint and painted all of our flat roof twice, even painting the first course of bricks above where the felt is fitted into the brickwork joints. All felt joints were given 4 coats of protection.
There is, and has been for many years, a shallow pool of water lying above our lounge window. This doesn't drain away, it evaporates over the course of a few dry days, so I'm fairly certain that the damp isn't coming from there, or any other part of our roof.
I was wondering if it is possible for water to enter our neighbours flat roof and leak into our part. The dampness is only near our neighbours wall and there's absolutely no dampness showing in any other rooms covered by flat roofing.

Thanks for any advice.

 

[ree]

Ponding on flat roofs is always a bad sign.

Roofs often leak in one place and present in another.

Dont jump to conclusions - find causes?

Why not post some pics of the interior damp signs and the external flat roof?

 

[Border Reiver]

Ponding on flat roofs is always a bad sign.

Roofs often leak in one place and present in another.

Dont jump to conclusions - find causes?

Why not post some pics of the interior damp signs and the external flat roof?

I've spent a while today scrubbing, scraping and hosing away most of the gunge from previous paint jobs & I'm going to wire brush it and sweep the area clean. Oddly enough, despite me using s lot of water, none leaked into the house. Could the leak be coming from next door's flat roof?
The DIY place suggested I re-paint the area with Isoflex once it's clean and dry. Don't know whether to try that or get a qualified roofer to have look.

 

[ree]

Thank you for the pics:

The wet area understructure has possibly dropped a little - get a long straight edge and level on the flat roof and look for a fall to discharge of around 1:40 or 1:48.

Next door appears to have a RWP from the main roof discharging onto the flat roof - does your side have a discharging RWP also?

The felt flashing arrangements appear to change on your side of the flat roof property join - just by the cables. I would suspect that small area?

Cant be sure but the felt seems to have a couple of hair cracks.

When the roof is dry pic & post it again. Then gradually water test from the lowest point up to the highest. From the pic angle, the roof looks very flat?

What you have is the cheapest and flimsiest possible arrangement - perhaps think about installing a pitched roof - you have the dimensions for a pitched roof.

 

[Border Reiver]

The rain water pipes actually go through the flat roof and discharge into a drain in the porch. The "cracks" you see are just where I couldn't manage to scrub off the old roof paint - a wire brush should do that OK. These roofs are very flat and are now around 50 years old, although ours was re-felted about 10 years ago. I'll think about the pitched roof idea. I was hoping to just paint it with Isoflex for now and get it done properly after the winter.

 

[Border Reiver]

Thank you for the pics:

The wet area understructure has possibly dropped a little - get a long straight edge and level on the flat roof and look for a fall to discharge of around 1:40 or 1:48.

Next door appears to have a RWP from the main roof discharging onto the flat roof - does your side have a discharging RWP also?

The felt flashing arrangements appear to change on your side of the flat roof property join - just by the cables. I would suspect that small area?

Cant be sure but the felt seems to have a couple of hair cracks.

When the roof is dry pic & post it again. Then gradually water test from the lowest point up to the highest. From the pic angle, the roof looks very flat?

What you have is the cheapest and flimsiest possible arrangement - perhaps think about installing a pitched roof - you have the dimensions for a pitched roof.

I did as you suggested and got a quality roofer to install a pitched roof. It's sorted the problem and we needn't worry about it any more. Thanks for your help.

 

[ree]

Thanks for letting us know how it turned out.

AAMOI: Border Reivers migrated to the USA centuries ago - President Johnson and President Nixon and Neil Armstrong were all, of course, descendents of those early immigrants.

edit:
Johnson, Nixon & Armstrong (first man on the moon when Nixon was President) were all name descendents of names that are still current in the Borders - long may it be so.

 

[Border Reiver]

Thanks for letting us know how it turned out.

AAMOI: Border Reivers migrated to the USA centuries ago - President Johnson and President Nixon and Neil Armstrong were all, of course, descendents of those early immigrants.

Interesting. I came from a part of the borders and my family name is one of those Reivers names. Our family have been in that region for centuries.