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Flat Roof Upstand


Nickster14

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Hi all,

 

I completed my self-build 4 years ago and have been living in it fairly happily until last year.  The master bedroom is underneath a terrace deck and we suffered significant water ingress causing damage to the ceiling.  We identified a number of issues with the EPDM roof covering which the warranty company agreed to pay To correct.  When the builder came round to quote, he pointed out that the upstand under the patio door was only about 30mm when it should be at least 75mm to conform with building regs.  The short upstand is probably a contributory factor to our leaks but the only sure-fire solution is to replace the patio door with a shorter one to produce the required upstand.  The annoying thing is, both the building inspector and the warranty inspector signed the work off!  Can I make a claim on my warranty to get the issue corrected?

 

thanks in advance,

 

Nick

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You could, but I think in2-3-4 years time you will be sick of it and just fix it. 

Tbh that’s just my take on all warranties. 

 

Did they have a detail drawing showing the 30mm upstand that they should have spotted or do you think they should have spotted it on site. 

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The drawings didn’t really show it in much detail but the inspector signed off the deck during a stage inspection.  I’m sick of it now and plan to fix (when building work resumes!) asap but a new, shorter, window will be expensive and I want to recoup some of the costs.

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Not helpful to you, but I saw one other exact example of this when visiting other builds. In this case it was for patio doors from a bedroom leading on to a flat roof.

 

In that instance, the warranty company chose to specifically carve-out the issue from the warranty cover. I think the self-builder chose to continue without any remediation of the problem and I haven't heard whether the issue has subsequently caused problems.

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1 hour ago, Nickster14 said:

When the builder came round to quote, he pointed out that the upstand under the patio door was only about 30mm when it should be at least 75mm to conform with building regs.  The short upstand is probably a contributory factor to our leaks


I’m not sure I agree with that statement ..?

 

Ask the builder where in the regs it says you have to have a 75mm upstand as I can’t think where it is. 
 

Also, it indicates that you have a drainage issue, not a roofing issue. 30mm is very deep - if you have 30mm of standing water on a flat roof then the falls are incorrect. That needs resolving first, and I would be looking to fix that if the membrane has got to come off.  
 

How big is the roof and which way does it slope to lose the water ..? 

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1 hour ago, AnonymousBosch said:

 

Might you  ( @Nickster14 ) be thinking of the recommendation for protection against rain splash  - 150mm above a flat deck?


yes however that’s removed at doorways - level thresholds etc. 
 

Sounds like an exercise by the builder in rear projection protection. 

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Thanks so far.  I think the builder is quoting a recommended upstand against a British Standard so I may be mistaken.  My technical manual, however, does say that the parapet wall should have an upstand of 150mm and this can be reduced to 75mm under the patio door.  I can’t see any exclusions in my policy accepting responsibility for a lesser upstand of 30mm.

 

We have had loads of issues with this roof and the warranty has already paid to correct some problems but this has uncovered a number of other factors that I wanted to correct whilst the original work was being completed and not have to do them later.  It’s a complicated situation but these are the issues that I have identified:

 

1.  The roof is flat, like really flat, with no fall.  This was an error in timber frame design that wasn’t picked up by the architect. The technical manual allows this if the covering comes with its own 10-yr warranty which it does.  There is a drain to the side of the deck which allows most of the water to escape.

2.  The patio window is fitted into the timber frame and not into the masonry.  This meant that the cavity gap had to be sealed.

3.  The windows fit the aperture in the frame almost exactly leaving little room for manoeuvre and definitely no room to vastly increase the upstand or give loads of room to correct the lack of a fall..

4.  The existing roof covering is EPDM and this has been incorrectly installed at corners and and joints but has not yet failed.

 

My minimum proposed works to correct the above is as follows:

 

1.  Remove the membrane and deck and construct a fall.

2.  Replace EPDM with GRP.

3.  Move the patio window outwards to be sealed to masonry and bridge the cavity.

 

The builder is unsure or whether there is enough upstand to allow a suitable fall and suggested the shorter window for the rain splash issue and fall.

Edited by Nickster14
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2 hours ago, mvincentd said:

I also concur that Building regs would impose such requirements.  I have a 10mm upstand in a similar scenario which was actually designed in collaboration with BC.

How did you drain the deck and what roof covering did you use?

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11 minutes ago, Russell griffiths said:

Can you chop the timber lintel out above and lift the door upwards to save on buying a new door ???

obviously more work but no door cost. 

Just an idea don’t shoot me. 

 Sadly no, I have a triangular window that sits above the patio door and above this are the steels that hold the masonry.

56665D28-E183-48D6-9A82-687033ACCC99.jpeg

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The builder has suggested getting a smaller triangular window or cutting the existing one down to allow the whole assembly to move up.  I’m concerned that if we go that way the corners of the patio door will be stopped by the steel.

36D0D23C-303B-471D-B5BA-FA5361226193.jpeg

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Which way do the rafters run on the flat roof ..?? And what is the make up of the roof ..? Is the insulation between the rafters ..??? 
 

This may sound bizarre but I would run the water toward the door, and put a drain in front of the doors - make it slope and basically get rid of the water as fast as possible. 
 

What is the decking surface on top of the EDPM..??

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46 minutes ago, PeterW said:

Which way do the rafters run on the flat roof ..?? And what is the make up of the roof ..? Is the insulation between the rafters ..??? 
 

This may sound bizarre but I would run the water toward the door, and put a drain in front of the doors - make it slope and basically get rid of the water as fast as possible. 
 

What is the decking surface on top of the EDPM..??

The rafters run away from the house.  The decking was/is composite board which I tried to use as a roof as such - it worked perfectly but we still got water on the roof itself.  The window faces East and we had a lot of driving rain into it over the winter and I suspect this highlighted the flaws in the seals.

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So is the problem the decking breaching the gap for the sill..? If you create a gap then the water will have to drain somewhere and can't get as high as the seal.

 

Detail threshold photos would help

 

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No, it’s not the decking.  There is a 50mm gap between the decking and the patio door.  The upstand under the door is max 30mm.  I think our issue is a combination of the door not being sealed into the structure and the water not draining away fast enough and inundating the joints at the top of the upstand.

 

The strips to the side of window are temporary and I have removed some of the decking in preparation for work being done at some point in the future.

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I am not sure what your threshold detail is, but I would expect the EPDM to lap up the 30mm at the bottom and almost into the room.

 

The cill should be well bedded down on mastic and sealed to the EPDM.

 

Even if you do not have much fall there is no reason water should be getting in.

 

This seems like a combination of poor design and detailing and poor installation.  If the water is coming in through the door, remove it and fit it correctly.

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i would be doing as @Mr Punter suggests, however, i would take the epdm/fibreglass into the house and return up the threshold to the limit of being covered by internal flooring. this would then work as a lead tray in a dormer does. that way there would be no need for external mastic and would allow any water to run away. i would definitely stay away from re-sizing the triangular window, an expense that shou;dn't be required and may not give you much benefit.

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Thanks for the fix advice, I had considered running the roof into the house and back up the upstand but I haven’t been able to discuss with the builder.

 

We’ve [usefully] deviated from my original question so, given that the warranty company signed off something that didn’t meet the requirement of their own technical manual can I make a financial claim to correct it even if the lack of upstand isn’t directly attributable to my issue?

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On 31/05/2020 at 12:46, Nickster14 said:

How did you drain the deck and what roof covering did you use?

The marine ply deck of my terrace falls very slightly but sufficiently away from the sliding doors and run-off ultimately just drains to ground.  The deck is covered with Wecryl 230 system.

Dont take too much from this, its unlikely to be useful to you, and its not a design i'd have chosen had my hand not been forced by steel position.  I was only trying to illustrate that bc can be somewhat flexible regarding upstands.

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