Capping stones waterleak

[festive]

We had some concrete capping stones laid on top of our exterior rear wall over + cavity to inner wall on our ground floor flat roof extension.

Since they have been laid we have experienced alot of damp and leaking of water below where the rear window sits underneath these capping stones.

I remember when they were laid i believe lead was only used as an apron to run water off below the course where a breather strip ran to allow the flat roof to breath, the lead did not span the cavity to the exterior wall. Bricky recommended painting a brickwater seal over the the stones and especially the cracks in the mortar? Or do they need to come up and have a dpc or some layer placed over cavity?
We are looking at moving this year dont want to spend too much.

Thanks.

 

[freddiemercurystwin]

A dpc should have been used under the coping stones or better still a stepped tray.

 

[wessex101]

What Freddy said. That is very basic stuff so whoever built it or designed it was an idiot. Assuming it was built recently you should be going back to the guilty party and insisting they do it properly. As for the "Bricky" recommending painting a sealant on the coping stones! He clearly isn't a bricky, just a wally with a trowel.

 

[theprinceofdarkness]

Most likely cause of the leak is the joint between adjacent coping stones. (What did they use to stop the mortar falling into the cavity?).
Frank