Tom Posted June 20, 2023 Share Posted June 20, 2023 Finally thought I was making progress over the last few weeks, but of course the dry weather was just a smokescreen, and once again the self-building gods piss in my eye. Most of the roof is now felted and battened, but still seems to be letting quite a lot of water through in the recent heavy rain - is this normal?? Link to comment Share on other sites More sharing options...
joe90 Posted June 20, 2023 Share Posted June 20, 2023 NO, can you identify where exactly the rain is coming in? 1 Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted June 20, 2023 Share Posted June 20, 2023 Absolutely not normal, the membrane should be fully water and wind tight without anything covering it, i.e. tiles. Have you any photos of it in its various states? Link to comment Share on other sites More sharing options...
Tom Posted June 20, 2023 Author Share Posted June 20, 2023 Link to comment Share on other sites More sharing options...
Tom Posted June 20, 2023 Author Share Posted June 20, 2023 Link to comment Share on other sites More sharing options...
Tom Posted June 20, 2023 Author Share Posted June 20, 2023 Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 20, 2023 Share Posted June 20, 2023 45 minutes ago, Tom said: ... but still seems to be letting quite a lot of water through in the recent heavy rain - is this normal?? No. We need to know the source - one small tear is enough to let in loads of water. Photos from under the felt will help greatly. The felt itself (if its a common branded felt ) is highly unlikely to leak. 1 Link to comment Share on other sites More sharing options...
joe90 Posted June 20, 2023 Share Posted June 20, 2023 Yes you need to be under the felt when it rains or someone with a hose outside whilst you look for the leak. 1 Link to comment Share on other sites More sharing options...
Tom Posted June 20, 2023 Author Share Posted June 20, 2023 Not possible unfortunately, our roof is composite panels, 2x2 timbers running down this and felted over that. I can see lots of drips running down the panels under the felt, but no idea where the water is getting in. Link to comment Share on other sites More sharing options...
joe90 Posted June 20, 2023 Share Posted June 20, 2023 Bugger! Frankly the felts got to come off again and be re done 🤷♂️ Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 20, 2023 Share Posted June 20, 2023 1 hour ago, Tom said: ... and once again the self-building gods piss in my eye. ... My sympathy. Loads of us here are wincing with you. There is a positive angle on this ..... It doesn't matter what the issue is,... there will be many more. The process of dealing with them is important. They train you (us, all of us) to supress the emotion - anger often - and become analytical. And to realise that there is an answer to this problem. You will solve the problem. And after you do that a few times, you can start to draw on the confidence engendered by the experience of getting it right. Especially when you've rescued a sh!tty situation. 6 minutes ago, Tom said: Not possible unfortunately, our roof is composite panels, 2x2 timbers running down this and felted over that. I can see lots of drips running down the panels under the felt, but no idea where the water is getting in. All the panels? Every panel? Everywhere? Doubt it. Focus on the section that is leaking. The drip will be lower than the water entry point. Focus on the upstream area above the drip. Wait until the rain has stopped (important) Up on the roof strip back that section of felt - carefully, slowly Look for drip marks on the top of the composite panels The leak(s) will be above (higher up the slope) than that spot Hold the felt up to the light - your looking for a small tear or set of tears My suspicion is less than careful handling of the felt...... Forget it until tomorrow's sunshine : go down the pub and forget it til then. Good luck Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 20, 2023 Share Posted June 20, 2023 Roofers call it weathering - IE it should stand the weather - maybe they didn't count on the rain so had not got it all fully weathered!? Link to comment Share on other sites More sharing options...
Temp Posted June 20, 2023 Share Posted June 20, 2023 54 minutes ago, Tom said: How high up each side does the lead go under the membrane? How were the joints in the lead done? This drawing shows a roof meeting a chimney but against a wall I would go higher. Two bricks or more rather than the one shown.. Link to comment Share on other sites More sharing options...
Barryscotland Posted June 20, 2023 Share Posted June 20, 2023 Our breathable membrane leaked like a sieve and we had to hold off on the screed getting poured till all the slate was on which held us up over a month, roofer said it was down to all the staples that the joiners had used to attach it to the sarking and that it should not leak. We never redid ours which we will probably come to regret. Different setup than yours though as just slate onto sarking Link to comment Share on other sites More sharing options...
Jenki Posted June 20, 2023 Share Posted June 20, 2023 Are you sure it's leaking and not condensation? It's been very humid( in Scotland) I doubt it's different in England. It can be surprising how much condensation you can get.. Also how windy has it been, the pitch looks shallow, (but that could be photos,) are the horizontal laps big enough and are they tapped? We're building in a windy location so will be using felt with tape to prevent water being driven in. Take a Big breath, it's better finding faults now, and fixing them l, than lying in bed and finding it still leaks.. this is a positive although it might not feel like it. 1 Link to comment Share on other sites More sharing options...
saveasteading Posted June 20, 2023 Share Posted June 20, 2023 I've always been good at tracing back leaks. I don't know why, or why other people find it difficult, esp so called roofers. I think it is logic. The final drip is vertical. Plumb where it lands exactly up to the drip point. Mark or otherwise record it. In bright daylight you might even see a hole. Then work out how it got there. If that is on the underside of a metal panel, try to watch it running Composite panels don't leak. So it is likely creeping from a puddle or stream in the membrane or a batten If the roof is by a builder, then get them to sort it by completely stripping and redoing. Keep photos and films of the leaks as they happen. The likeliest source? Either a tear in the membrane of through a nail hole where the batten hasn't been pulled tight to the rafter. And incredibly, I have encountered roofers who don't understand overlapping in the right direction. Good luck. BTW what quantities are we looking at? Fills a bucket, or a mug? Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 20, 2023 Share Posted June 20, 2023 2 hours ago, saveasteading said: ... And incredibly, I have encountered roofers who don't understand overlapping in the right direction. ... Spelling mistake there..... should have written '... credibly...' Link to comment Share on other sites More sharing options...
makie Posted June 20, 2023 Share Posted June 20, 2023 (edited) Breathable felt can leak with heavy rain over a prolonged period. The valley is most likely letting water in, doesn't look like it's been felted properly. Is it lead? if it is it's been installed incorrectly. Also the lead gulley, is it one piece? please tell me it has some elevated areas or expansion joints welded in? Edited June 20, 2023 by makie 1 Link to comment Share on other sites More sharing options...
Tom Posted June 20, 2023 Author Share Posted June 20, 2023 Thanks all for your replies everyone, sorry its taken a while to reply. In asnwer to a few questions, it's definitely leaking rather than condensation @Jenki. Quite a few areas where its dripping down the walls from under the membrane, but because the membrane is nailed under battens there is no way I can peek under to see where. The lead in the gully goes up about 200mm both sides I think. There is a fall on it, but not sure how much (2%?) and the run of approx 10m is in about 10+ pieces, apparently with "lead mate" between the sheets where they are lapped. @makie is this done correctly? I already had the guy redo it once as the fall was so shallow there was water pooling up and over the laps. Likewise in what way has the valley not been felted properly? @saveasteading - the panels should't leak, but they are screwed down to z-purlins (and the 2x2 timbers on them the same) and in a few areas where the screw didn't take or whatever there are holes going through with no screw, if that makes sense. So essentially can't rely on the panels as a watertight layer unfortunately. There are quite a few tears in the membrane all over tbh. Quantity is a bucket or so. @ToughButterCup, cold beer time. So, to rectify this, could I just put another layer of felt OVER the battens? The final covering is currugated sheets, so even with membrane over the batten there will be air flow between this and the sheet. Trouble is, if I get it all stripped off, there's no guarantee the second time it gets done will be any better.... Link to comment Share on other sites More sharing options...
makie Posted June 20, 2023 Share Posted June 20, 2023 20 minutes ago, Tom said: The lead in the gully goes up about 200mm both sides I think. There is a fall on it, but not sure how much (2%?) and the run of approx 10m is in about 10+ pieces, apparently with "lead mate" between the sheets where they are lapped. @makie is this done correctly? I already had the guy redo it once as the fall was so shallow there was water pooling up and over the laps. Likewise in what way has the valley not been felted properly? It should be built up with steps to allow it to shed properly and make sure water doesn't creep back. Like this The felt should be ran down the valley and then the felt on the pitches should be lapped on top or into the valley. They have also used non-copper nails in it, plus lead valleys should never be nailed on the flat or further down than the top 3rd of it to allow for expansion. 1 Link to comment Share on other sites More sharing options...
Radian Posted June 20, 2023 Share Posted June 20, 2023 20 minutes ago, Tom said: So, to rectify this, could I just put another layer of felt OVER the battens? The final covering is currugated sheets, so even with membrane over the batten there will be air flow between this and the sheet. Doesn't sound like a good idea to me. It certainly wouldn't be for a tiled or slated roof as the membrane could push up the tiles with over pressure behind it. What I don't see is any way for the water running down to your horizontal battens escaping and not pooling up on top of them. While there, water will find its way through the nail holes. Normally if the felt was to be laid over a solid base layer, there would be vertical counter battens to space off the final horizontals - thus letting water flow unimpeded. Draped over a trussed roof, the membrane would deliberately not be stretched tight to facilitate the same thing. 1 Link to comment Share on other sites More sharing options...
Gus Potter Posted June 20, 2023 Share Posted June 20, 2023 (edited) 14 hours ago, Tom said: Not possible unfortunately, our roof is composite panels, 2x2 timbers running down this and felted over that. I can see lots of drips running down the panels under the felt, but no idea where the water is getting in. Tom.. unfortunately I think you should get this looked at by an independant person that has experience of inspecting this type of self build work. The general standard of workmanship looks poor. What is going on in that valley? Why are there different types of membrane and why are they not laid flat. Cost wise if you go for this kind of inspection allow 1 day for the inspector to have a reasonable look over at the superstructure. If bad and dimensional checks plus a more in depth look is required add another day. Then one day reporting. Daily rate for this would be around £300 -400, plus travelling on top. Sounds a lot but you seek to recover most if not all from the builder. Unless it was you that did the work in which case it's time for.. what can you do to make this ok.. you'll get help here on that. One obvious reason is that the cross temporary battens will be trapping water.. it is a vapour membrane and they not designed to resist standing water. Also, your valleys will be leaking like a seive as again you have got the valley material on top. It's almost like breaking the miniscus on the breathable membrane. In the old days we used to use type 1F bituminous felt that could stand all types of abuse.. you are using a modern fabric that is a bit more like a Goretex jacket.. compare this with a wax Barbour.. that can take all kinds of abuse and still remain water tight.., but a bit sweaty right enough. Edited June 20, 2023 by Gus Potter Link to comment Share on other sites More sharing options...
dnb Posted June 20, 2023 Share Posted June 20, 2023 I'm far from a roofer (but did batten and slate much of my own house roof). I agree with Gus Potter with the source of leaks likely to be the detailing around the valley. There appears from the photos like there is no easy way for water to drain down the roof on membrane past the battens so it is making its way in to the house. Breathable membrane is a good thing, but it only works right if the details are implemented correctly. Based on advice (from people here) this was an area where I paid a lot of attention and put in a lot of time. I too am surprised by the lack of counter-battens. I was told (because I have a SIPS roof) that it was required to allow the roof structure to be properly drained and vented. Link to comment Share on other sites More sharing options...
Tom Posted June 21, 2023 Author Share Posted June 21, 2023 Thanks both. There are counterbattens, as per previous post there are 2x2 battens running vertically down the roof, then membrane, then battens going across. I agree that the membrane does seem to be pulled very tight which holds it against the underside of the battens. @Gus Potter can you explain what you mean by the valley material being "on top"? The lead here sits on 8x1 boards which themselves sit on the 2x2 counterbattens, so the lead is above the level of the membrane. Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 21, 2023 Share Posted June 21, 2023 @Tom, decent weather forecast for today.... May I suggest a hose pipe and a lawn sprinkler spraying such that small sections of the roof are sprayed - and the others not. And a look-see underneath while its running ...... Looking at your images - how about 'creeping up' on your valley? By that I mean trying to find out if one side of the valley leaks, but the other doesn't? Link to comment Share on other sites More sharing options...
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