MJNewton Posted January 11, 2022 Author Share Posted January 11, 2022 1 hour ago, Annker said: @MJNewton Thanks for updated the thread, good to hear that the roof is performing as it should! Yes, although my Dad did say something along the lines of 'Of course, if he got the vapour control layer detailing right then any water that did get through the roof surface would be channeled down into the cavity and you wouldn't necessarily see it'. Thanks Dad... ? Link to comment Share on other sites More sharing options...
Gordo Posted January 11, 2022 Share Posted January 11, 2022 Thought who’s resurrected this old thread. So wasn’t going to comment about the madness of anything other than option 1. Until I got to the feedback. You made the correct choice after listening to all the various opinions and advise offered to you. BS are just guidance for best practice. BC do not enforce BS and as the roof did not contravene the performance requirements of the regulations (the approved documents are not regulations) they could not force you or the builder to do any remedial work. Obviously they would prefer you follow best practice guidance 1 Link to comment Share on other sites More sharing options...
steveoelliott Posted January 12, 2022 Share Posted January 12, 2022 The ponding on my newly replaced membrane is far worse than I have seen in these posts... This work was completed last April and whilst (knock on wood) it has been water tight, it does bother me. I now have slabs over the top on pedestals but can see the large volume of water underneath. This roof holds ~40 liters of ponding water; I know as I used a wet and dry vac to clear the water off before laying the slabs / pedestals. The problem in my case I think is the falls aren't brilliant but this is made far worse by a step up to the outlet... previously the outlet was incorporated using the PVC material whereas now it is a solid plastic outlet. I intend to get another roofer to take a look at it in the spring / summer... the previous roofer wasn't interested in correcting this. His words "It will be alright mate". Unfortunately I had paid for the work and it didn't rain for several weeks after this so I wasn't aware of the issue. It's a shame as the roof work is actually pretty neat. Link to comment Share on other sites More sharing options...
MJNewton Posted January 12, 2022 Author Share Posted January 12, 2022 (edited) 47 minutes ago, steveoelliott said: The ponding on my newly replaced membrane is far worse than I have seen in these posts... This work was completed last April and whilst (knock on wood) it has been water tight, it does bother me. Perhaps that's the nub of the issue here and something we should (both) be trying to separate - the factual aspects related to the roof doing its job and the emotional aspects relating to our disappointment, failed expectations, achieving value for money, desire for perfection, knowing the issue could've been so easily avoided etc. Even if you've got more pooling water than I have, is it still a cause for concern? The weight won't be an issue nor will it freezing (or increased algae/detritus) causing a slip hazard be an issue, and I think they are the two mains concerns expressed in the standards and best practice guides relating to pooling water. Will the longevity of the membrane be reduced by longer exposure to water? I honestly don't know, but certainly the specifications, ratings and approvals etc for the liquid membrane I used don't seem concerned with this - indeed as I mentioned it is often used in swimming pools and water parks where constant/regular water content is the norm. I really do think the biggest problem to solve is in our minds here, which on reflection ought to be a good thing as it should within our gift to address and mitigate - and potentially at nil cost too! Edited January 12, 2022 by MJNewton Link to comment Share on other sites More sharing options...
Gordo Posted January 12, 2022 Share Posted January 12, 2022 Some flat roofs are designed to be fully submerged in ponded water. I think the idea is to avoid thermal shock on membrane. Never saw it done and don’t think it popular in UK. I would not fret over ponding water on a flat roof it may arguably be beneficial in a smaller scale roof so long as the joints are good. Link to comment Share on other sites More sharing options...
steveoelliott Posted January 12, 2022 Share Posted January 12, 2022 (edited) 5 hours ago, MJNewton said: Perhaps that's the nub of the issue here and something we should (both) be trying to separate - the factual aspects related to the roof doing its job and the emotional aspects relating to our disappointment, failed expectations, achieving value for money, desire for perfection, knowing the issue could've been so easily avoided etc. Even if you've got more pooling water than I have, is it still a cause for concern? The weight won't be an issue nor will it freezing (or increased algae/detritus) causing a slip hazard be an issue, and I think they are the two mains concerns expressed in the standards and best practice guides relating to pooling water. Will the longevity of the membrane be reduced by longer exposure to water? I honestly don't know, but certainly the specifications, ratings and approvals etc for the liquid membrane I used don't seem concerned with this - indeed as I mentioned it is often used in swimming pools and water parks where constant/regular water content is the norm. I really do think the biggest problem to solve is in our minds here, which on reflection ought to be a good thing as it should within our gift to address and mitigate - and potentially at nil cost too! Yes I agree with you here... The problem I see already is silt / debris as a result of the ponding water. The way I see it is ultimately I am still not happy and it plays on my mind (however illogical) and the biggest thing to me is the fact that if the roof ever were to leak, it would be horrendous given the amount of ponding water. What is frustrating is how easy it would have been to ensure this didn’t pond prior to laying the new membrane versus doing this retrospectively. In addition it doesn’t pond by design but rather the result of a lack of forethought / attention to detail. That said a lot of folks including those I trust on here have said it’s not a real issue to be concerned about. Edited January 12, 2022 by steveoelliott Link to comment Share on other sites More sharing options...
saveasteading Posted January 12, 2022 Share Posted January 12, 2022 Was the roofer responsible for the structure underneath being to appropriate slopes? How much fall is there other than this problem area? 1 Link to comment Share on other sites More sharing options...
steveoelliott Posted January 12, 2022 Share Posted January 12, 2022 11 minutes ago, saveasteading said: Was the roofer responsible for the structure underneath being to appropriate slopes? How much fall is there other than this problem area? In fairness they just replaced the membrane and that is why I haven’t been more persistent with them rectifying this. But… I would expect any roofer to check the falls and avoid a step up to an outlet and advise prior to laying a new membrane. Lesson learnt on my part, I would in future ask for all this to be checked and insist on their being no / minimal ponding. Link to comment Share on other sites More sharing options...
saveasteading Posted January 12, 2022 Share Posted January 12, 2022 Is the roof all too flat? Theoretically you could screed over this area with bitumen and take up all the puddle, then a bit more to create a slope to the outlet. Messy and perhaps unnecessary. Or can the outlet be altered? Cant really see it in the pic. Link to comment Share on other sites More sharing options...
steveoelliott Posted January 12, 2022 Share Posted January 12, 2022 2 minutes ago, saveasteading said: Is the roof all too flat? Theoretically you could screed over this area with bitumen and take up all the puddle, then a bit more to create a slope to the outlet. Messy and perhaps unnecessary. Or can the outlet be altered? Cant really see it in the pic. There is definitely a fall and I believe the issue to be the step up to the outlet in the corner. It is this I intend to discuss with another roofer after they’ve of course checked the falls are present etc. It should be feasibly possible to lower the outlet by say 10 mm and solve the issue. 1 Link to comment Share on other sites More sharing options...
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