Roofing Question

We have had problems with walls being damp in patches when it rains. we have a butterfly roof and coping stones.

Roofers say roof ok. do not know where water coming from.We have had lead flashing put against parapet wall and roof, cemented under coping stones but still same problem when it rains. Could it be that there is water ingress under coping stones. Not sure where to begin. Advice been to render parapet wall and put waterproof membrane under coping stones also to plaster internal walls with waterproof plaster. Help

8 Answers

Best Answer

If there is brickwork exposed to weather, ie, driving rain then it is possible that the cement course needs attention. Check there are no gaps, broken, bricks etc. If so it may need re pointing. Also, broken roof tiles, even if they are only broken on the corner.

Answered 24th Jan 2012

Walden Building Services

Member since 17 Jan 2012

If all the lead valleys and flashings are okay, you might want to check that there is a dpc under the coping stones.
If the brickwork is in poor condition, then render will help.
I wouldnt bother with water proof plastering, you need to solve the problem of the leak first.

Answered 23rd Jan 2012


Member since 29 Oct 2008

Hi, in regards to your question on damp walls, yes, if your parapet walls are old and in some need of repair: Re-pointing with sand and cement mixed with EXTERIOR GRADE PVA or you can render the whole wall if your bricks are decaying, but the mix should have a Waterproof PVA that acts as a sealer and waterproofer

Answered 23rd Jan 2012

Thanet Property Maintenance

Member since 20 Nov 2011

We had a problem similar with coping stones over a cavity wall. On the underside of the lead flashing under the copings condensation formed then ran back into the property. Took ages to find but a few vents solved the problem

Answered 23rd Jan 2012

jd kent

Member since 14 Jun 2008

if the coping stones have had a dpc membrane placed across the cavity all the way up and where it joins the main building there should be no water coming in throughthe joints to the copings, water can penetrate into the bed joint but if this has been done properly water rarely ingresses through the bed joint, possible cause could be from the parapet wall joints if these have not been pointed properly as it sounds like the water ingress is hitting the tie irons and coming through to the inside wall

Answered 23rd Jan 2012

MD Construction

Member since 16 Apr 2009

could be penetrating through the walls and not the roof ,old rendered walls are forever having this problem

Answered 23rd Jan 2012


Member since 7 Jun 2008

how old is the house ?

Answered 23rd Jan 2012

ADR Property Maintenance

Member since 1 Mar 2009

There's cracked tile or your felt as gone the end and it's running in to the caverty have a look at your roof to see if a tile as gone check felt is going into you gutter the ridge caps will be the last thing to go hope this helps

Answered 23rd Jan 2012

Wyevale Property Care Ltd

Member since 22 Jan 2012

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