Leak Flat Roof/Rendered Wall

Interest

Hi all,

We had a small flat roof replaced 3 years ago (felt to rubber), however, once or twice a year since, we get water coming through the ceiling below. The most recent occasion has lead me to pull the ceiling down & have a look. Lintel was soaked, boards aren’t looking great.

The roofer who provided a 20 year warranty claims that his roof is fine & the problem is water is getting into cracks in the pebble dash above the roof & trickling down behind the lead flashing. There are cavity trays but he says they have been rendered over & the current lead flashing is now above the dpc & that there are no weep holes

does this sound realistic as it’s all new to me, I’d never heard of cavity trays until last week?

our main issue is that he didn’t realise this when doing the roof replacement & flashing 3 years ago & has now removed some render around the flashing to show us & now of course on any water test, water gets into this new gap. He also used the previous flashing line in the render when sealing the new stuff

He is suggesting that we have new cavity trays fitted higher up, with weep holes & look to have the wall re-rendered.

any guidance is appreciated.

stuart45

Can you put some external and internal photos on?

Interest

Hi, yes I have attached some below. The sheet above the roof has been added to protect the cracks in render.

Jeepers_Creepers

Could you take a whole-roof shot too, please?

stuart45

Hard to be sure from photos, but it does not look like it's coming down the cavity, unless the tray is so low it's sending it into the roof deck 

Apjs87

I've had this problem with my flat roof too. Spent thousands to remedy. Started by replacing the whole felt section and the lead, then went higher onto the main roof and replaced a section of the felt, battens and fitted a dry verge. It still leaked! Only when a drip bead was installed just above where the lead is channelled into the wall has the leaking stopped. Even though that lead looks sealed it is only 25mm into the wall so water can still get in. Maybe mention the drip bead install? And look higher if I were you. I hope you get this resolved

Jeepers_Creepers

These photos make more sense now, looking at them again.

The roofer's explanation does hold water; a cavity tray should be above the flashing line and also have drain slots. The mystery, then, is how it didn't leak before this new roof if the roofer used the same flashing line height? Or did it leak in a similar manner - once or twice a year (also bearing in mind that the past year seems to be more wet than usual).

Interest, can you measure up the cavity as seen in your first photo and confirm the height of the tray?

If covering the rendered section above has stopped further water coming in (tho' it could also be because it hasn't rained so much recently?), then that would at least confirm that the water is coming through the render and not from further up. But due to how infrequent it does leak, it would be hard to confirm this.

If that tray is mounted low with its weeping holes behind the flashing, then, well, you know...

olbas_oil

Interest said:

Hi, yes I have attached some below. The sheet above the roof has been added to protect the cracks in render.

I am looking at a house for sale that has similar lines in the rendering. Is that a sign of moisture running down? 

Jeepers_Creepers

I think these are just cracks that have been filled in an effort to stop rain getting in. Slight cracks like this is usually not a problem; the OP of this thread has, I think, bigger issues.