Penetrating damp from party parapet wall

9 Jul 2021
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United Kingdom
Hi everyone,

We have spotted some damp spots in our bathroom. This is on a party wall with no pipe this side, so I figure this is penetrating damp downwards from the parapet above. And indeed, on inspection I can see some damage on the gutter valley and cracking mortar.

1. Please have a look at the valley, this is not lead valley but something like asphalt (?) that you can walk on. What should I use to patch it up, bituminous mastic?

2. The mortar cracks along the line where this valley meet the parapet wall. I can repoint it, but wonder if there is any treatment I can do to seal the porous structure inside (that allow rain water to seep downward)? I have heard a builder said chemical filler but not sure what type it is.

3. On the other side of the parapet wall I can see it has been repaired like this before (see photo Repair). Would that work and what sort of material is that?

Thanks for your help.


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stand back and pic both sides of the parapt and the roofs next to there a chimney stack?nearly everything in the pics needs repairing plus the pointing is a joke.

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