Yaffles

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We have a leak

Weebles

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Thought I'd add this to the blog but would be very grateful for some advice.

 

Some construction background: 

MBC timber frame, flat roof, pumped insulation in roof void.  Make up of roof is Sarnafil (hot welded) laid on a felt base, on top of 22mm OSB roof (with a slope), on top of 22mm OSB roof deck (flat - slope provided by battens to create the fall), then 400mm pumped insulation between the roof joists, air tight membrane, battens, 12mm plasterboard and skim.

Roof lights on the flat roof (including a lovely round one, subject of another blog post).

 

Yesterday we had some drips coming through the finished ceiling, about 700mm from the edge of our circular rooflight.

 

We cut away some plasterboard to see what is going on.  Plasterboard soaking wet, batten soaking wet and looks like the insulation is soaking wet.  There is some water damage closer to the rooflight too, visible in the photo, but we started our cut at the plasterboard edge which is where the water started seeping through - the low point I guess.

 

Have contacted roofing supplier and rooflight supplier (both of whom fitted their product).

 

What shall I do next?  I can't help feeling that without detecting the source of the leak neither supplier is going to help us.  Any thoughts?  Cut away our ceiling until we find the edge of the problem? (as we get nearer to the rooflight bit of course we are 7m off the floor ☹️)

 

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Maybe look up top first. Garden hose and someone inside on the phone although water can travel a lot. Its got to be around the junction of window and roof covering 

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Really sorry to hear about this. Hope you find a solution.

 

My assumption is that once Warmcel becomes wet it will slump, meaning that you are going to have to remove it and re-pump no matter what, at least for the voids where water has entered.

 

I would call Rich Hibbert at PYC, the UK importer (Technical Manager, always very helpful, T: 01938 500 797) and check my assumption is right. If it is, then you could consider starting to remove it now, which would give you a much clearer view of the leak. I appreciate that doing that in 7m section will require some sort of scaffold.

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Really sorry to hear this, no easy way to find water tracking in. Hosepipe on roof and keep digging till the source can be seen. Personally I hate flat roofs fir this very reason.

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Really sorry to hear about this, it must be awful. Makes me nervous as we have a large area of flat roof and it is covered in Sarnafil.

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This looks pretty grim, not an easy thing to get fixed, either, in terms of the amount of disruption it will cause. 

 

@jack had a similar problem with a flat roof leak soaking the pumped cellulose in his build.  I can't remember the details, but seem to recall that it meant removing all the soggy cellulose, fixing the leak, letting everything dry out, then reinstalling the cellulose , after making 100% certain that the new VCL was totally sealed up.

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You need the roofer and the window people on site for an inspection when (if) the weather improves.  Between them they should work out what has gone wrong and suggest a remedy.

 

As others have said, junctions are the most likely area of failure, especially if they are not correctly designed and detailed.

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1 hour ago, Oz07 said:

Maybe look up top first. Garden hose and someone inside on the phone although water can travel a lot. Its got to be around the junction of window and roof covering 

+1. If roof leaks, its the junctions. 99% of the times.  Fixing it can be difficult once everything is installed (like in your case) and bodging around with it most likely will create a problem later, so finding the source is really important, but difficult. If it's been installed by a competent company, they should come back to inspect it, but always tricky if several are involved (window installer will point the finger on the roofer, roofer on the window installer).

To narrow it down, you could cover certain areas with tarpaulin/foil and then put water on the roof around the area, keep moving your "dry spot" and have someone check inside wether water drip/flow increases.

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Does house insurance not cover this?

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Or at least the legal side if you have it

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On 05/03/2020 at 10:00, Jeremy Harris said:

 

@jack had a similar problem with a flat roof leak soaking the pumped cellulose in his build.  I can't remember the details, but seem to recall that it meant removing all the soggy cellulose, fixing the leak, letting everything dry out, then reinstalling the cellulose , after making 100% certain that the new VCL was totally sealed up.

 

Exactly this. Took us nearly a year from start to finish. Two rooms were affected. In our case, it was due to poor sealing between the roofing membrane and the outlets through the parapet wall. Another one had started failing when inspected, so we insisted on all five being replaced.

 

The roofer agreed to rectify, and fixed the membrane fairly promptly. Unfortunately, they then insisted on putting the rest through their insurer (even though the total costs were less than £2k from memory), which turned into a nightmare. Their attitude was so poor that if I hadn't had several million things on my plate I'd have sued them for every incidental cost possible, but in the end I decided the stress wasn't worth it and settled for the actual paid out costs. 

 

@Weebles, feel free to PM me if you want to talk about what happened and how we handled.

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6 minutes ago, jack said:

Two rooms were affected. In our case, it was due to poor sealing between the roofing membrane and the outlets through the parapet wall. Another one had started failing when inspected, so we insisted on all five being replaced.

 

My build is looking to do this with scupper drains, and i would be very interested to hear about possible failures to make sure it doesn't happen on mine.

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1 minute ago, Moonshine said:

My build is looking to do this with scupper drains, and i would be very interested to hear about possible failures to make sure it doesn't happen on mine.

 

That was exactly what we had problems with.

 

PM me if you want to discuss.

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8 minutes ago, jack said:

PM me if you want to discuss.

 

i may take up on that in the future.

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Might something have shifted in the recent storms, or the membrane have been pierced somehow?  Our garage roof (thankfully, not insulated) was damaged by a slate that blew off the main roof in one of the (many) recent storms and water leaked through inside the garage roof.  Good luck with the inspection and repair.

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Thanks for all the comments so far. Here’s an update: 

MBC (Darren) came onsite as on another local job. (they are brilliant, those guys) And together we took out a load of soggy insulation and put a small hole in the lower roof deck. We still have more to do as haven’t found the edge of the wet insulation yet. Leak appears to be down a bit of OSB nailed onto a roof joist below the upstand of the roof light. OSB roof deck appears dry in that location. 
roof inspection yields nothing obvious. It’s hammering with rain so can’t test anything. A piece of plastic over what we thought might be the problem has not stopped the drips (every second when it is raining).

Inspected roof light mastic seal as advised by them. No issues of note. And roof light overhang appears deep enough to prevent any water ingress. 

Awaiting roofers on site. Guess that might be tomorrow now. 
waiting on the insurance front so we can see which party is liable and whose insurance will pay up. 

luckily we own a scaffold tower (for our hedges, v helpful during the build) so put that back up pronto.

 

@jack your story fills me with trepidation but I expect we’ll be down some similar route on timing.  
 

Got to get roofer to admit liability first so need to have a better go at leak location inside first.  
 

once it stops raining we can get back on the roof to properly test it.

 

MBC and we agree this has been going on for months - the sodden insulation and lack of evidence of a failure point seems to indicate a tiny hole and slow damage.

 

and to think we were thinking we were almost there 🙄

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Those photos are bringing back all sorts of nasty memories. You have my sympathy!

 

 

01 - Wet area.jpg

3_-_Water_1.JPG

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Really sorry to hear this, let me know if I can help out in any way.

 

I have to take my hat off to MBC here, they were equally helpful when I had the render issue - sending Brendan to site for half a day to work with the contractor to get to the root of the issue two plus years after the house was built.

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3 hours ago, jack said:

Those photos are bringing back all sorts of nasty memories.

 

Wow - your photo is almost identical to the mess we exposed today, condensation on the lower side of the OSB with soaked insulation.

 

We have exposed even more of the area now.  The middle section is the problem area.  

 

It has been a long day and we have just finished clearing up the mess (that pumped in insulation takes up alot more volume when it is pulled out!).  We have looked back at all the build photos and the construction drawings for the upstands for the roof light.  Its a bit of a puzzle but we are hypothesising that the water is leaking in through a mastic seal onto the frame of the rooflight (which sits under the glass).  It is then leaking through a screw hole into the upstand (timber) (the frame was fixed into the upstand with vertical screws), travelling down to the bottom of the upstand where it joins the roof joists and then spreading both above and below the vapour membrane (the drips are coming from below the membrane, but the insulation within the membrane is soaked also.  Of course there could be a leak in the roof material somewhere but that theory is not so obvious given where the water is being found and the lower roof deck being dry. 

 

Tomorrow and Saturday are supposed to be dry (no rain hopefully) so we plan to get some water up there and selectively test the various areas.  I have messaged both companies inviting them to be present.  I'll video the tests so we have some evidence because fixing this is going to cost someone some money.  Thanks for all the advice, and supportive messages today.  It is good to know you are all there.....

 

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Stay away from that circular reveal I remember the blog post!

So do you have to repair your air tight membrane after or is a vcl different? How do you do it go mad with tape?

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2 hours ago, Oz07 said:

Stay away from that circular reveal I remember the blog post!

So do you have to repair your air tight membrane after or is a vcl different? How do you do it go mad with tape?


the air tight membrane will need to be reinstated. MBC advises yesterday that it can be patched with tape and a new bit of membrane. And then new insulation pump led in. So no issues there.

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Can’t wait to get home from work today. The sun is shining. The roof should be dry. There’s a hole somewhere. I’m going to get home and get up on that roof with a hosepipe and find it. If it’s not in the roof surfacing then we’ll let the roof dry and hosepipe the roof light tomorrow. That’s my Friday night. Nothing I’d rather do 😂

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I offered both the roof light company and the roofing company the opportunity to witness the test. Both declined.  I hope this doesn’t mean we will end up with a fight on our hands. 🤞

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Well done on progress so far.  It is certainly no fun doing this but I have seen a number of sites near me where the contractor has had to go back to remedy issues.  The recent weather has brought lots of defects into focus.

 

Once the soggy insulation is all stripped it should be easier to see what has gone wrong.

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