steveoelliott

So mine is the bubble top… Megaflow HE 210. It has instructions on side to replenish bubble. It was already drained to change the TRV. Reading online it seems fairly common for these to break down based on my google searching with folks installing an external EV as a workaround / solution. On mine A white EV has been installed on the cold water inlet to the cyclinder. I will have somebody else check this in due course just for peace of mind.

Sorry, so the Megaflow HE has an internal expansion baffle / vessel. It is apparently common for these to breakdown.

The plumber has now installed a white Zilmet 18L potable EV on the cold inlet to the Megaflow having deduced that the internal baffle on the cyclinder had broken down. This has reduced significantly the water hammer on the hot to the point that unless I shut off the taps like a "ninja" there is no hammer and even then less than before. One thing I have noticed and will question him on when he returns is the noise that comes from the EV. When the cyclinder is heating you can hear sounds that I can only describe as similar to a whoopee cushion or squeaking. Should the EV be silent in operation or is some noise expected?

Just to circle back... The roofer came out today and took a look. He acknowledged it was not ideal and suspected grit or potentially the odd screw head has popped up. He was however adamant that they wouldn't come through once the fleece is down even under weight of slab on pedestal etc. He did offer to cut out the worst ones and patch but stated if it was his roof, he'd leave it alone. I still felt a little uncomfortable so in the end I made a statement... "if this roof does leak then will you take the slabs and fleece membrane off" rather than me having to do all the donkey work. He agreed but was adamant it will be fine. He said since he was here now, it would be very easy to cut out and patch the areas if he was concerned rather than the alternative of it leaking and having to deal with that.

Thank you... Well for now, i'll leave the EV... Sounds like I need to first find a plumber who really understands unvented and G3 beyond the text book.

I presume the additional secondary PRV is to make sure that both the pressure of source for cold into supply and into the cylinder are the same; thus both hot and cold same pressure. What does the non return valve on the hot water outlet?

Thank you... what is the need / purpose of both of these when there isn't a balanced cold supply. Just so I can steer them

Coming back to this after some time... I have been advised today by my plumber that as my Megaflo doesn't have a balanced cold supply (we inherited this system), we can't install the 8L expansion vessel.

I spoke to the roofer this morning... his analysis over the phone was this must just be bits of grit left over before they laid the membrane. He was adamant that they will never come through but I was far from convinced. I've asked them to come around to take a look... I certainly feel uneasy leaving them as is.

Thanks Mr Punter. My existing membrane had a leak and I opted to replace it... I know the previous was mechanically fixed but was told it would be easier / preferable to use adhesive this time. I'll see what the roofer says when he returns from holiday and takes a look. I take your point on adapting pedestals because without a doubt it will coincide with their placement but it aggrieves me to need to do this on a new roof. Moreover, there is a risk that the object may still penetrate the membrane. I think either way even if the roofer deems this to be outside of their scope, I will need to get it tended to.

Thank you... When the old roof was mechanically fixed, then yes I did see these. However, they don't look like they did. Thanks... Not beyond the realms of possibility... the reason I suspected screws was owing to the number I have found; some are less protruding than others. The only way to tell is to the let the roofer inspect the membrane; in the meantime I intend to keep off it / avoid walking on those spots.

Hi Folks, On a recently laid PVC membrane, I've noticed there are numerous (some worse than others) objects pushing up on the membrane from underneath... I've attached pictures of some underneath; some you can't see very well in photos though. My fear is these may be screws that hold the marine ply deck down on the celotex insulation boards. If this is the case, it will be a complete nightmare to resolve I presume; either membrane up or a patch work quilt. I didn't notice these previously... I have made previous posts about ponding on this roof but only noticed these today whilst sweeping up some of the silt left by the said ponding. I wonder if this has been caused by the recent heatwave in the UK? The membrane was replaced back in April and was previously mechanically fixed and now is glued rather than using mechanical fixings. The guy that did the roof is on holiday but I will be calling him when he returns. If it is the board screws popping, I'm not sure where responsibility lies as he didn't touch this. It never did this for 10 years previous with the old membrane; maybe the mechanical fixed roof held things in place better. Thanks for reading... I'd be interested if others have experienced this / seen similar.

In fairness the outlet is a standard size outlet and if the fall was correct would be more than ample to get the water off the roof... the problem I have is ponding water due to there being a step up to the outlet. I wish I had specified to the roofer that I wanted the falls checked before the new membrane was laid. I am at the point where if I do have more issues with this roof terrace in future, I’ll just get a firm in to extend the small bedroom over it and be done with it ; of having a proper roof on top. Would be a shame to lose the terrace though but we’ve never really had it since we moved in due to problems.

Thanks... Like I say... otherwise a fairly neat job. Here is a picture showing the gaps a little better. If it is OK to squeeze some more sealant in the gaps without pulling it out then that should be easy enough.

Noted. Thanks Mark.

My research and the good people on this community explains that pooling in and of itself does not present an issue. However, personally I'd aim to avoid it.

Please correct me if I am wrong, but if the water came level / just over the bottom of the flashing, wouldn't that present a problem owing to the capillary action of water? Thus effectively being drawn up behind the flashing?

Hi Folks, On an otherwise fairly neat job, I have noticed that areas around the leadmate sealant on one of the saddles have small gaps per the photograph. Now whilst it doesn't "appear" to be presenting a problem, it's more of a minor cosmetic one as far I can tell. I came across this while getting ready to clean it down and treat with patination oil (something seemingly omitted after being installed). Couple of questions for the experienced, firstly is it worth doing anything with? My father takes the view it's not causing you a problem so leave it alone. Secondly, what would be involved, would it require all the sealant to be pulled out of the chase and reapplied? I haven't been able to find anything about re-pointing with leadmate / sealant. I guess it hasn't probably been needed for the most part. Thanks in advance...

Thanks Mark... One of my principle concerns is with this much laying water, if you did ever get a leak it would be huge as the water doesn't get off the roof. I guess a leak is a leak and maybe I think about things to much lol

So... I went through a real conundrum with our flat roof made up of PVC and used as a terrace. When we looked at the house, it had a leak and that was supposedly resolved by renewing the silicon between the up stand and wall (or so we thought). If the truth be known my gut told me the roof would cause us problems if we brought the house, but I chose to ignore it!! The roof terrace is ~4m x 4m and has two parapet walls. Around a month after moving in, following no real rain but a hard frost we had some damp / blown plaster over the top of the wall underneath one of the parapets, near to where the outlet is for the terrace. I got some folks round to look at the roof and remove all the slabs, pads, protective fleece etc. to inspect the roof and outlet. Everybody was convinced it wasn't the roof stating it looked in good condition and was a "good job". I was persuaded it must be the copings letting water in. So off they came, to be re-laid with a DPC underneath (apparently this had been neglected when built but there was nevertheless a cavity tray underneath") Now... this seemingly fixed the problem for many months until it was getting warmer and we brought all the slabs back up to terrace. After the first bought of heavy rain we had two massive damp patches on the ceiling but nothing further on the wall this time. I was now convinced it has to be the roof based on location and the amount of water. In the first instance I removed a group of slabs (around 7-8) near the corner of the outlet to take a look but couldn't see anything... It rained long and hard for days and no further leaks; I was perplexed until I remembered I'd moved the slabs. I put them back and the leak returned the next day! I proved this theory several times by placing and removing them. Once again... all slabs came off the roof and I had folks round to look at the roof. All again said it all looks to be fine but clearly accepted there must be an issue. They were puzzled by the removal of slabs stopping the leak and I don't think gave it much credence but I certainly wasn't lying. All of them offered to either do a complete renew or repair (the later would involve overlapping all seams etc.) I was so sick of it that I opted to renew the membrane completely and also replace the old copings with new ones. When it came to doing the job... both parapet cavity's were bone dry before being replaced with new porcelain ones. When the roofer came he was almost laughing and joking saying there is nothing wrong with this roof it must have been the copings etc. etc. then he cut the membrane and saw a huge damp patch. As he cut further and stripped the deck he found the root cause; a bad weld where the membrane meets the up stand. He said this would never have been found without going through the stripping process. I can only suspect that the slabs must have exacerbated this condition further and led to a leak or at least enough water ingress to get through the ceiling. So in short, from my layman's experience, flat roofs and parapets are a nightmare if not constructed and detailed impeccably. I will actively seek to avoid both flat roofs and parapets on any future house I purchase. All of this probably doesn't assist you a great deal but I wanted to share my experience. My advice would be to not rule out anything and try to find a builder / roofer who is meticulous to assist in locating your leak.

So... with all the recent rain, the roof hasn't dried out since I started this topic. With the downpours overnight, it's back to where it was. I'd estimate ~30 liters just standing. Most people I speak to say they wouldn't worry about it... I think I'll have to accept and live with it. I just like things to be right. Hopefully the protective fleece, support pads and slabs will help raise the level and shift this. I reached out directly to IKO Polymeric and they stated that their membrane can withstand even severe ponding without affecting it or the guarantee. However, they did state (as I knew) it is good practice and part of the BS standards to ensure water drains off as quickly as possible. I think this will be yet another lesson for me in hindsight... I wish I had made a point about wanting to ensure water drains off the roof quickly and not stand. Whilst the roofer recognizes the water remaining on the roof is not ideal, trying to resolve it now would involve extensive work that he believes in unnecessary.

Thanks. I’m going to after a few rain events... it’s a nightmare getting them up and laid so want to be sure. I had them off once before for a repair that didn’t work out and only found out after spending an afternoon laying them lol

Thanks folks... appreciate the feedback...

Hi, Having recently had a defective flat roof replaced... per another post. I've noticed an issue with pooling water. In fairness the old roof suffered with it to some extent but less so as the outlet was made up of the membrane material. The new outlet is a single piece welded to the PVC and sits ever so slightly higher. Effectively there is a small step up to the outlet which is far from ideal. I mentioned it to the roofer and he explained that the membrane would be unaffected by this and in fact could take being soaked throughout it's life and not effect the guarantee. The details on IKO Polymeric's own site second the fact the membrane can withstand pooling. It was my understanding however that as a rule standing water should be gone within 48 hours of the last rain event... We had some heavy rain overnight Tuesday and early into Wednesday. I've attached some pictures below with a timeline of the pooling. Wednesday 5 hours after rain: Wednesday 13 hours after rain: Friday 53 hours after rain: Saturday - 83 hours after rain I am ultimately sticking down a protective fleece, paving support pads and then promenade slabs on this deck so that may or may not help to a certain extent. Should I be concerned at this pooling? What I have researched suggests not, although ideally the water should run off freely. I'm not really minded to ask folks to start pulling this apart now etc as that would mean disturbing the lead flashing and lowering the outlet in the wall. Please let me know your thoughts...

Fingers crossed... Even though there is a DPC I think I’d have felt more comfortable with bed of mortar and pointing rather than a PU adhesive to stick them down, external grout between the stones and a bead of silicon between top of bricks and stones. I’m assured by the folks that did it all will be fine...