How much technical detail should a construction drawing show?

[MJNewton]

8 minutes ago, joe90 said:

Being a DIY fanatic and the little it will cost for a bit of plastic I would wrap the parapet up and try to see if that stops the leak. If it’s not conclusive then get experts in. 

Yes - completely agree. Furthermore,  if it stops further ingress of water that can only be a good thing whilst the decision is made what to do next. 

Edited January 2 by MJNewton

[Adsibob]

1 hour ago, joe90 said:

Being a DIY fanatic and the little it will cost for a bit of plastic I would wrap the parapet up and try to see if that stops the leak. If it’s not conclusive then get experts in. 🤷‍♂️ it would still help if you had a sectional drawing of that wall makeup.

Yeah, I think you are right. The concern I have is that the leak is very intermittent. For example we had two ingresses of water yesterday, several hours apart, yet absolutely nothing today, despite there being quite a bit of wind and rain today. Also, somewhat weird that there has been no water ingress for the last 7-8 weeks since the weep vents went in. So I suspect it’s a very slow leak that requires water to accumulate over time, in a particular way, caused by a certain rate of rain and possibly a certain wind direction. But without knowing what those variables are I’m not sure I’d be able to do any testing which is scientific. In that I could put the tarp up tomorrow, it could rain for a month, but because the rain wasn’t blown in a CV particular direction, it might not cause the problem, yet I would mistakenly conclude the tarp had fixed it.

[dpmiller]

pull the wall down and rebuild with an undamaged cavity tray *and* weep vents in the correct place

 

/ are you sure the vents were fitted properly and not cut in half/shoved in a drilled hole as bodgers have done in the past?

[Adsibob]

So I got up on the roof today. It’s pretty pathetic. The parapet detailing is poor. I can see three different ways water could be getting into the parapet. To make matters worse, in the last two weeks, an outbreak of mushrooms has grown towards  the top of the parapet wall. I counted 12 in total. Difficult to see from a distance, as our wall is more or less mushroom grey, but up close today, unmistakeable. 
 

I’ve sent photos to the RICS surveyor who confirmed my fears. He thinks it should be relatively easy to redo the parapet capping, which is the main issue, but he was a little concerned that with the wall being so wet that it is now a thriving mushroom fest, the insulation is likely to be wet. As the bricks and mortar have been sealed, it may take a very long time to dry. He thought that once the parapet capping is fixed it should dry “eventually” but couldn’t be sure. 

Incredible. 
 

I probably should schedule an appointment with my cardiologist as a precaution. 

Edited January 3 by Adsibob

[Mr Punter]

If it is any consolation I think the brickwork does look good.

 

I have used aluminium coping for parapet walls in the past and it performs well but may not suit the minimalist aesthetic.

[joe90]

Well that I think is good news in that you have identified a problem and you can move forward. Did you engage an architect? Did he specify this crap capping? If the detailing is poor is it worth going after your builder.?

 

I get it if you just want to resolve this yourself without involving those in your build. Perhaps ask here for recommendations of products to cap that wall 🤷‍♂️.   Onwards and upwards eh!

[Adsibob]

2 hours ago, Mr Punter said:

If it is any consolation I think the brickwork does look good.

 

I have used aluminium coping for parapet walls in the past and it performs well but may not suit the minimalist aesthetic.

Thanks.  The brickwork was indeed done really well, as was the majority of the work, which is why this f&£k up has come as such a surprise. I think part of the problem was that to make a long story short, the parapet is where two different tradesman’s scope of works meet. One tradesman was doing the roof membrane, that was meant to overlap the parapet, the other tradesman was effectively responsible for everything else, ie the rest of the house. To make matters worse, I think the design was very ambitious, because it didn’t use the aluminium profiles you mention on the rear elevation, just on the parapet walls at the side elevations. (And those parapet walls are free of mushrooms!) So to work, it had to be executed meticulously. But it wasn’t.

 

 To answer @joe90’s question, I think small errors were made by all parties involved, including me as ultimate project manager. Enough errors that if I challenge any of them on it, they will just point the finger at the other tradesman and we will all just fall out, so it’s probably not worth going on a witch hunt. As long as it’s not too expensive to resolve, I rather keep people onside so that they can help me resolve it.

@Mr Punter I’m considering utilising an aluminium profile to cap the rear wall’s parapet, and would be interested to know which type you recommend. Do the ones you’ve used have an integrated drip profile? 

Edited January 3 by Adsibob

[Mr Punter]

I have used Guttercrest for copings and they seem pretty good and reliable.  You can probably drape some DPC under the copings for belt and braces.