Waterproofing a solid block parapet wall.

[Julian Oakes]

Hello, I was hoping someone could help please. I have a solid block parapet wall on the roof of my garage. On one side it runs down to a drainage channel that is part of a GRP roof. It is capped with black granite slabs overhang by c.25mm each side and they are polymer sealed between them. It is rendered all round and painted with sandtex and has a good drip trim over the GRP channel.
My problem is that the wall inside the garage below is very damp and this has affected the plasterboard ceiling badly. There is no apparent ingress or leakage point anywhere. Any suggestions would be most welcome, especially since I have a similar parapet on my parents house pre- render and id like to avoid this issue from the word go. Advice on proven waterproofing products (render, coatings, wall capping) would be great.
Thanks in advance.

 

[datarebal]

..

 

[Julian Oakes]

Hi. Was this reply meant for me? If so, not sure I get your drift. Cheers

 

[bobasd]

OP,
you gave a pretty good general description of things but it would help if you posted pics of every relevant thing inside & outside the garage.
How long has this been noticeable in the garage?
Any puddles on the floor?
When was either of the roofs last worked on?

 

[datarebal]

So

Hi. Was this reply meant for me? If so, not sure I get your drift. Cheers

Sorry not for you