CH_18 Posted January 7 Share Posted January 7 (edited) Hi everyone, We have recently had GSE in roof solar panels and trays fitted to our new build roof which is now complete and slated. Since then we have been getting wet patches/streaks on the membrane visible from below. My roofer has been round and said he's 90% sure it's condensation, which I'm not convinced by. The patches only form when it's raining which seems to be the big give away for me that it's water ingress and not condensation, but saying that, I'm no roofer. Any thoughts/advice would be much appreciated. Thanks Edited January 7 by CH_18 Link to comment Share on other sites More sharing options...
Conor Posted January 7 Share Posted January 7 (edited) Photos from the outside please. Closeups of the flashing and any taken during installation. What's with the sheets of OSB? Edited January 7 by Conor Link to comment Share on other sites More sharing options...
saveasteading Posted January 7 Share Posted January 7 Leak. It could be anywhere between the wet point and all the way upslope of it. Is the timber wet? Link to comment Share on other sites More sharing options...
Russell griffiths Posted January 7 Share Posted January 7 Get on the scaffolding with a hose pipe. Make sure to sprinkle water like rain, don’t squirt it upwards into gaps. Link to comment Share on other sites More sharing options...
CH_18 Posted February 3 Author Share Posted February 3 On 07/01/2024 at 15:37, Russell griffiths said: Get on the scaffolding with a hose pipe. Make sure to sprinkle water like rain, don’t squirt it upwards into gaps. OK bit more progress on this. I'm even more dumbfounded. So I had a hose constantly on different parts of the roof flat out at hour intervals this week and nothing shown up on the inside. No patches, no streaks, nothing. I took a panel off (in the rain) to expose the GSE tray underneath and there was no running water on the tray, the top flashing and panel was taking the majority of the water away, but what I did notice was the tray had what looked like condensation on it, wiped it with my hand and was soaking. So is that what is showing up on the membrane?? Another test I did was put a piece of DPM across the opening in the tray to see which side of the DPM was getting wet. Went down this morning after rain, wet patches visible on the inside again, pulled the DPM out and found that the external side was dry and the internal side was wet with condensation?? So seems like possibly condensation but I still don't understand the science on it 🤷🏼♂️ Link to comment Share on other sites More sharing options...
CH_18 Posted February 3 Author Share Posted February 3 For a bit more info the patches are still only showing when it's wet weather. Not particularly rain, it's been misty damp today and the patches are visible inside 🤷🏼♂️ Link to comment Share on other sites More sharing options...
CH_18 Posted February 17 Author Share Posted February 17 Can anyone offer any advice? Still battling with this. It's definitely not leaking. I've had a multiple water hoses running full whack on the roof at 1m intervals and the patches didn't appear, bone dry. I did however get a borescope through the membrane to where the patches were showing and noticed drips coming from the back of the GSE tray and onto the membrane, which seems like a condensation issue. This is a new build, ventilation at eaves and ridge, breathable membrane but no insulation has been installed yet to monitor the issue. I have since insulated between 5 of the rafters as a test to see if the patches disappeared, but they came back next time we had damp weather. Again, patches only show, at a continuous height all the way across the panels and in wet weather, I'm out of ideas. Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted February 17 Share Posted February 17 Have you contacted GSE? also their install guide - https://www.gseintegration.com/wp-content/uploads/2023/09/GSE-IN-ROOF-SYSTEM-Guide-dinstallation-EN-4.2.pdf looks to be batten and counter batten to leave a nominal 25mm air gap to remove condensation. and the full install manual - https://www.gseintegration.com/wp-content/uploads/2023/04/GSE-IN-ROOF-SYSTEM-Manuel-dinstallation-EN-V13.1.pdf does your installation follow everything in there? Link to comment Share on other sites More sharing options...
CH_18 Posted February 17 Author Share Posted February 17 Hi Mike, yeah been through them guides and videos 236 times looking for answers. Can't seem to find anything, changed all the EPDM washers thinking it may have been them, but no improvement. I'm 95% sure it's condensation but don't understand the science behind why we're getting it. Massive amounts of air flow, house still being built so no heat on, although no insulation on that side of the roof yet. Spoke to GSE they were of little help, they're only focus was on the small holes in the membrane. Link to comment Share on other sites More sharing options...
Conor Posted February 18 Share Posted February 18 Have you ever observed this moisture when it's been cold and dry? Like the other week during that cold snap. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted February 18 Share Posted February 18 This looks like condensation to me, so you must have dew point conditions around the in-roof GSE plastic formers - the fact that it is wet both sides supports this theory. So warmer damp air hits a cooler surface and condensation forms as the air goes through its dew point. Calculating dew point in the traditional way is a bit of a pain but in 2005 Mark Lawrence came up with a much simple calculation which gives a good approximation, above 50% Relative Humidity (RH) and not far out below. Td = T - ((100 - RH)/5.) you can read all about it here: https://climate.envsci.rutgers.edu/pdf/LawrenceRHdewpointBAMS.pdf. So you can then play with the numbers and get an impression for just when the condensation will happen. I created a simple spreadsheet to help me understand why I was getting vast quantities of condensation on the air tight membrane before the insulation was pumped in. So if the RH is 80% and your air temperature is 9oC and if your plastic unit is at 5oC you will get condensation by this calculation (and the full one). Your situation is all on the outside but it still means that at for every 5% RH drop from 100% the temperature delta increases by 1o C (at 100% the dewpoint is the temperature if you think about it!). You can look at this another way - how is it a problem? You get condensation in roof structures on the outside, the build up design is so arranged that when it happens it is dried out as soon as possible and is kept off the absorbent parts by the membrane. 1 Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted February 18 Share Posted February 18 9 hours ago, CH_18 said: Hi Mike, yeah been through them guides and videos 236 times looking for answers. Can't seem to find anything, changed all the EPDM washers thinking it may have been them, but no improvement. I'm 95% sure it's condensation but don't understand the science behind why we're getting it. Massive amounts of air flow, house still being built so no heat on, although no insulation on that side of the roof yet. Spoke to GSE they were of little help, they're only focus was on the small holes in the membrane. how about speaking to a solar installer? Might be something they’ve come across before. Link to comment Share on other sites More sharing options...
dpmiller Posted February 18 Share Posted February 18 I'd crack on getting VCL/insulation/PB up personally, you don't currently have "normal" conditions yet? 1 Link to comment Share on other sites More sharing options...
Marvin Posted February 18 Share Posted February 18 You don't usually get leaks all over the roof. whats the state of the building below? People working below warming up the building? Floor slab or screeding recently done? My guess would be cold air passing on the outside of the roofing felt with warmer moist air in the roof space condensing... Good luck. M Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 3 hours ago, MikeSharp01 said: This looks like condensation to me, so you must have dew point conditions around the in-roof GSE plastic formers - the fact that it is wet both sides supports this theory. So warmer damp air hits a cooler surface and condensation forms as the air goes through its dew point. Calculating dew point in the traditional way is a bit of a pain but in 2005 Mark Lawrence came up with a much simple calculation which gives a good approximation, above 50% Relative Humidity (RH) and not far out below. Td = T - ((100 - RH)/5.) you can read all about it here: https://climate.envsci.rutgers.edu/pdf/LawrenceRHdewpointBAMS.pdf. So you can then play with the numbers and get an impression for just when the condensation will happen. I created a simple spreadsheet to help me understand why I was getting vast quantities of condensation on the air tight membrane before the insulation was pumped in. So if the RH is 80% and your air temperature is 9oC and if your plastic unit is at 5oC you will get condensation by this calculation (and the full one). Your situation is all on the outside but it still means that at for every 5% RH drop from 100% the temperature delta increases by 1o C (at 100% the dewpoint is the temperature if you think about it!). You can look at this another way - how is it a problem? You get condensation in roof structures on the outside, the build up design is so arranged that when it happens it is dried out as soon as possible and is kept off the absorbent parts by the membrane. Thanks Mike, that's helpful So that would explain why condensation only occurs when it's wet weather, rain/damp/mist/drizzle. I insulated one side of the roof and left the panel side uninsulated so I can see what's going on. This might be compounding the issue possibly. I have tried insulating between 5 rafters just to test but the patches still appeared behind, maybe I need to crack on and insulate the whole roof for a proper test? What do you think? Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 3 hours ago, MikeGrahamT21 said: how about speaking to a solar installer? Might be something they’ve come across before. I've had two solar installers round mate to have a look and they are as dumbfounded as me? They say the install is fine, they mentioned the EPDM washers had exploded from using an impact gun so I replaced all of them and torqued them up? Apart from that they were also head scratching 🤦 Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 1 hour ago, dpmiller said: I'd crack on getting VCL/insulation/PB up personally, you don't currently have "normal" conditions yet? I think this might be my next plan of attack. I have got the borescope available so will still be able to see behind the insulation. Either that or I was thinking about cutting a piece of membrane out directly behind a panel to see what exactly is going on? Not sure on this idea mind because the membrane is what's keeping the water out ATM. If I was to cut some out any decent tips to seal a new piece in afterwards? Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 4 hours ago, Conor said: Have you ever observed this moisture when it's been cold and dry? Like the other week during that cold snap. Hi mate, no never, it was -5 degrees here the other week and I had no patches whatsoever, bone dry. This is what's dumbfounding me, I'm no physics expert, but I would have thought condensation would be affected by temperature and not weather? So unless it's purely the relative humidity outside that's increasing in the wet weather like Mike said is resulting in the ideal conditions for condensation to come closer and show up I don't know? Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 1 hour ago, Marvin said: You don't usually get leaks all over the roof. whats the state of the building below? People working below warming up the building? Floor slab or screeding recently done? My guess would be cold air passing on the outside of the roofing felt with warmer moist air in the roof space condensing... Good luck. M Cheers Marvin Yeah that's my thinking also, although like I said I have insulated 5 rafters and it made no difference behind these. So I may have unless to do the whole roof to fully test the theory. I have had the sand/cement screed poured in January but this was happening before and after that? Link to comment Share on other sites More sharing options...
Mr Punter Posted February 18 Share Posted February 18 I have had similar and think it may be condensation: Link to comment Share on other sites More sharing options...
CH_18 Posted February 18 Author Share Posted February 18 2 minutes ago, Mr Punter said: I have had similar and think it may be condensation: Ah interesting, have you got GSE in roof system? And does it only happen in the wet weather? Have you just cracked on and insulated hoping it will solve the issue? Link to comment Share on other sites More sharing options...
Mr Punter Posted February 18 Share Posted February 18 Not GSE, just metal rails. The solar guys attended to inspect and were due to get on the roof to resolve this. I don't know how they got on. Scaffold is down, so I will not be going up there. This only shows on the section of roof with solar. Link to comment Share on other sites More sharing options...
Redbeard Posted February 18 Share Posted February 18 Is the top metal rail perchance by that nail-plate? In which case could the moisture be where the rail bkt has (*if it has*) perforated the membrane? Of course whatever flashing detail was used should prevent this but it looks like you have a point of entry and then it's running down (or not; I may be wrong!). Link to comment Share on other sites More sharing options...
saveasteading Posted February 18 Share Posted February 18 It's in one line down the slope, so I'd say it is one screw at fault, at or above the start of the wet area. Link to comment Share on other sites More sharing options...
CH_18 Posted February 19 Author Share Posted February 19 FYI the last pic is not of my issue but someone with similar problem. Is the general consensus that cracking on insulating and installing VCL will hopefully sort the issue out? Link to comment Share on other sites More sharing options...
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