New roof but still leaks

[Dhalsim]

Hello.

We have a flat roof with a parapet and coping stones. See pics. We just (3 months ago) had a new epdm roof fitted but we are still seeing leaks, but in new places (edge of the ceilings).

I’ve been up and I can’t see any issues with the epdm (side note we have called the roofer but he has since gone out of business so getting him back to advice is currently non starter).

I suspect it is a separate issue with the coping stones. But would really welcome some advice.

In the pictures I’ve marked the points externally where the water is appearing internally, and looks like it corresponds to where the black marks are? presumably this marking is water run off and related to the leaks?

The cement between the coping stones looks ok to me but I wonder if looking like it doesn’t have any obvious leaks does not mean the mortar isn’t failing?

Any advice here would be much appreciated. I didn’t take close ups of the mortar but I can get them. Please let me know if other pics or info need to make any suggestions.

Many Thanks in advance.

 

[Koolpc]

 

[DiyNutJob]

It's possible the water came from a different part of the roof and drained to the lowest point.

 

[Dhalsim]

I don’t think so. The rest of the roof has new EPDM covering on. My initial thought was that detailing around this pipe might be at fault but also looks to be in good shape.

 

[freddiemercurystwin]

Did he have the copings off? Guessing not. What is under the copings? How high up the wall does the epdm go? Did he do the render? Got any pics of what it was like before? If the edpm is good then it has to be the copings/paparepet and (probably) lack of any flashing linking the epdm with any membrane under the copings - of which there probably isn't one anyway.

 

[Dhalsim]

No. Copings didn't come off. The old roof was felt and in bad shape. But I think this new EPDM job is ok which is making me think copings. You can see in the pics the EPDM only goes up to a couple of inches then he has beaded and rendered over to seal in the EPDM. That too looks good to mee and assume that new render will stop leaks but he won't have extended the EPDM all the way to the copings under the render. I doubt there is a membrane under the copings, they must ahev been down for years. Am i right in thinking copings these days should have a DPC underneath?

One investigative plan is clip a tarp on the copings over next few (rainy weeks) and see if that stops the leak and isolate the problem to the copings.

Thanks for all the help

 

[datarebal]

Not ideal relying on the render . It is cracked already . Maybe check the clip around the svp for tightness

 

[foxhole]

Epdm should lap up the parapet to give continuous coverage ,likely one side or both of the parapet wall have live render letting in water .
Go round tapping it to see if it’s sound .

 

[Dhalsim]

Thanks all. I’ll do some more checks this weekend and report back

 

[tell80]

Roger Bisby is a good plumber but he often talks bol...ks when he strays off his trade.
The above vids are not too clever, and the diagram is wrong.
He should stop trying to sell stuff and just concentrate on sound plumbing advice.

 

[DiyNutJob]

Roger Bisby is a good plumber but he often talks bol...ks when he strays off his trade.

I got the hybrid polymer sealant idea from him. It turned out quite brilliantly. It was transformational for DIY. It worked for my roof leak the other day, and countless other things before that. Today, I was filling wood with it.

 

[Nige F]

Roger Bisby is a good plumber but he often talks bol...ks when he strays off his trade.
The above vids are not too clever, and the diagram is wrong.
He should stop trying to sell stuff and just concentrate on sound plumbing advice.

And what is your trade ? do tell.tell. Where is the diagram wrong ? people need to know .

 

[robinbanks]

I agree with your proposal to test the coping by use of a tarp: cut a section of tarp a couple of metres wide, maybe 5 metres long, and roll a length of 2x4 up at each edge, then screw another timber on right though the tarp; keep checking the weather (windfinder.com is good) for a low wind, high rain day, then drape the tarp over the the wall so the timbers act as weights to keep it draped down half a metre either side and see if you get problems

The black marks indicate that water isn't dripping off the coping stones, but instead tracking back and soaking into the render at the top where the render meets the underside of the stone. Being as the render stays generally wetter there, mold and lichen growth is promoted leading to the marks

 

[DiyNutJob]

To prevent the water tracking/blowing back to underneath the coping stones, a bead of sealant in the corner where the render meets the coping stone could do it. The mortar joint between the coping stones also needs to be sealed. The smallest holes or cracks in the mortar could transport a huge amount of water. Digging out some mortar and applying sealant on top will be diy-able.

 

[freddiemercurystwin]

To prevent the water tracking/blowing back to underneath the coping stones, a bead of sealant in the corner where the render meets the coping stone could do it. The mortar joint between the coping stones also needs to be sealed. The smallest holes or cracks in the mortar could transport a huge amount of water. Digging out some mortar and applying sealant on top will be diy-able.

That's just a temporary bodge, if it even worked initially. Which it probably won't.