Leak caused by parapet wall/render/flashing

6 Jun 2015
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United Kingdom
Hi everyone

Was interested to know what's the best way to stop leaks coming through a parapet wall on our roof? Of course, it depends on what the problem is exactly but we have had quite a few different suggestions - coping stones, chemical sprays, different types of capping etc and are a little unsure which to go with.

I've uploaded some photos to this album here:


We live in the top floor flat of a 3 storey victorian property. One wall of our rear bedroom and the wall of the landing outside has had damp issues on and off for the last 12 years since we moved in. This wall is quite exposed as its not a party wall as it extends beyond the neighbour's property. The damp readings are highest at the very top of the wall where it meets the ceiling and is pretty much dry for the lower half of the wall.

Last February 2014 there was a lot of storms and we had a lot of damp enter into the bedroom and so we got a roofer to come in and he replaced some flashing on the bedroom roof that had come off. He also applied some new cement render to where he installed the new flashing.

However, its now June 2015 and although the damp has improved it's still giving high readings and we have tried redecorating but even with stain blocker stains and damp patches come back through.

We had the roofer come back to look at his work and he couldn't see any obvious signs of leaks and suggested some kind of chemical spray to make the bricks water resistant - ideally later in the summer once the wall has dried out as much as possible. He also peered over to the neighbours garden to see the pointing on the brick wall which looked fine. I also went to a neighbours garden to look at this wall and it looked fine and i took some photos. Access to this roof isn't easy but is just about possible through a small window.

We had other people quote on the work but they have recommended different things - some suggest coping stones to be added over the parapet wall. Others have also suggested chemical sprays to weather proof the bricks. We have also seen that sometimes people have lead flashing going higher up the parapet wall or even a lead cap or some sort of concrete render cap. Also other suggestions seemed to be that the original roofer should have used some kind of water resistant render.

I will put some photos up shortly but wondered what the consensus is as to how best to treat the problem of a possible leak coming through the parapet wall area?

Many thanks

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2 coats of render with waterproofer and coping stones.

Chemical sprays need re-applied every couple of years.

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