ToughButterCup Posted December 31, 2020 Share Posted December 31, 2020 (edited) Here's one to keep our @Russell griffiths happy, and to help reduce @SteamyTea's Schadenfreudesucht. Please could you review my thinking, and see if I've missed something. Thanks. Two years ago, just after the roof was tiled with Nulock cermaic tiles, a bit of a hooley blew up: long story short it blew some scaffolding planks off the scaff and onto the roof. Live and learn. Next time scaff plank clips. ? Here's part of what the storm did. and here's how I repaired it The photos were taken when the storm was still pretty full-on: I was clipped to the scaffolding with a full harness. Nulok is easy to replace though - and I was keen to get the job done to prevent further damage. Fast forward two years. Drip, drip...... WTF !!! how's that happened then? Dry up to now why, how, bugger it ... Debbie looked at me and didn't say If ya can't take a joke, don't self build . (my signature line) There's not much of a drip. In the recent South Westerly storm that knocked us all on our heels, (warm wind), not a drop came through the roof - or perhaps better put, not enough water leaked in the roof to come through the roof build up . When its frozen outside, there's no drip. When there's cold northerly rain, there is a drip. The roof build up is; Tiles Metal Batten Felt Counterbatten 200mm insulation (between joists) 100mm underboarding insulation batten 12.5mm PB Neither was there a drip when it froze ... this morning - freezing - no drip before we popped out to the shops, but there was a drip when we got back. Temperature had risen by 5 degrees...... No rain - but there was ice on the roof when we left, - the roof was dry when we got back. As I write this, the damp patch has all but disappeared in the PB. There is no roof space, so I cant see the exposed underside of the roof from inside. Heres a cross section - Why did it happen now? A bit of head-scratching and came up with the following - what have I missed? The repair to the tiles was done under pressure: it was quite dangerous - windy enough to be fully harnessed and clipped on. The repair to the tiles took about 15 minutes. Nulok is very easy indeed to replace - throw the broken tiles off the roof, slide in a new one. They simply clip in. What I did NOT DO was inspect the underlying felt because I was worried about being blown off the roof. I bet I simply missed a small rip or two in the felt...... If thats correct, given sufficient temperature contrast, there would be condensation on the bottom of the tiles. And maybe there's a bit of ponding on the felt... and the water makes its way through the small rip. And because its small hole, it takes ages to show up. Maybe it took that long to trickle through over 300mm of roof build up. Anyway, have I missed something? Constructive comments welcome. @PeterStarck - what do you think? (I ask becaue you have Nulok) Tomorrow, scaff goes up, fetch a roof ladder (although you can walk on Nulok tiles) and then a wait until there's a long enough weather window to whip some tiles off to look-see. Bye bye 2020. Lets hope 2021 is better eh? Edited December 31, 2020 by ToughButterCup 3 Link to comment Share on other sites More sharing options...
joe90 Posted December 31, 2020 Share Posted December 31, 2020 I agree with your assumption, as I was reading it, “torn felt” ran through my mind before I had finished. Good job it’s newlok as you said, easy to remove/replace slates/tiles. Link to comment Share on other sites More sharing options...
Gone West Posted December 31, 2020 Share Posted December 31, 2020 (edited) @ToughButterCup Hi Ian, sorry to hear about the leak. I can't think of anything, other than as you've suggested a tear in the felt. Not a lot of help I know. What are the two types of insulation in the roof makeup? I would have thought a fair amount of water would need to get under the felt in order to make it through 300mm unless it's very open cell type, non absorbent insulation. I can't understand why the direction of the wind would make any difference as the overlap on the tiles should prevent water being blown up underneath. It was a wet winter last year so why no leak then? Sorry more questions than answers. Edited December 31, 2020 by PeterStarck Link to comment Share on other sites More sharing options...
Temp Posted December 31, 2020 Share Posted December 31, 2020 I assume you replaced the tile with broken corner in second photo? Link to comment Share on other sites More sharing options...
tonyshouse Posted December 31, 2020 Share Posted December 31, 2020 Roof should be waterproof without relying on sarking 1 Link to comment Share on other sites More sharing options...
Jason L Posted December 31, 2020 Share Posted December 31, 2020 It sounds like what you suggest as It looks like you don’t have a drape in the felt, if anything it’s the opposite. So it could be that melting ice goes into the felt and can’t get away. Link to comment Share on other sites More sharing options...
ProDave Posted December 31, 2020 Share Posted December 31, 2020 Could it just be condensation on the underside of the tiles that was frozen, and thawed today? I have seen it "raining" from the underside of a box profile roof in such conditions. Still points to an issue with the felt. Link to comment Share on other sites More sharing options...
LA3222 Posted December 31, 2020 Share Posted December 31, 2020 (edited) I cant see how this can be simple like melting ice. For water to get past tiles, felt, and 300mm of insulation is more than just a simple drip from thawing ice. For the water to gwt past all this there must be a lot of it or it has been going on for a long time and is only now manifesting itself? In the old quarter I lived in EWI was put on and the tiles redone to account for additional wall make up. Took 6mths before water started coming through the bathroom ceiling from the chip shop work on the roof tiles. Started off as small drip, further investigation showed it had been going on for long time and caused all sorts of unseen damage - ended moving as loads of them got condemned (the drip caused asbestos to be disturbed). Went on a bit of a tangent there but my point is how can a drip coming through all that roof make up only be a bit of water - there must have been a lot more somewhere? The ceiling appears to be vaulted so the drip might not correlate with where the water is tracking from? Drill a hole to get access to the service cavity a use a camera to try and have a look? I can see the source of this issue as potentially difficult to locate unfortunately. Edited December 31, 2020 by LA3222 Link to comment Share on other sites More sharing options...
ToughButterCup Posted December 31, 2020 Author Share Posted December 31, 2020 2 hours ago, Temp said: I assume you replaced the tile with broken corner in second photo? Yes. 3 hours ago, PeterStarck said: ...I can't think of anything, other than as you've suggested a tear in the felt.... I would have thought a fair amount of water would need to get under the felt in order to make it through 300mm unless it's very open cell type, non absorbent insulation. I can't understand why the direction of the wind would make any difference ... The temperature of the air mass - from the south west warm, but wet - so little or no condensate. Freezing / very cold north wind promotes condensation ... drips 5 minutes ago, LA3222 said: ... For the water to gwt past all this there must be a lot of it or it has been going on for a long time and is only now manifesting itself? ... I agree: thats what worries me. Nowt for it but to get up there, pull some tiles off and have a look see. Thats one thing that's bloody brilliant about self building. I know exactly what to look for, and I can get on with it virtually on my own. Photos to follow. Ian Link to comment Share on other sites More sharing options...
MJNewton Posted December 31, 2020 Share Posted December 31, 2020 (edited) Rather than torn/damaged felt might it be coming through a hole where the felt is nailed to the rafters? I beleive that is why felt is draped to keep the water away from the rafters, but I don't know if that's as relevant for your particular roof construction type/materials. Edited December 31, 2020 by MJNewton 1 Link to comment Share on other sites More sharing options...
Temp Posted December 31, 2020 Share Posted December 31, 2020 I was just thinking on similar lines... 5 hours ago, ToughButterCup said: The roof build up is; Tiles Metal Batten Felt Counterbatten 200mm insulation (between joists) 100mm underboarding insulation batten 12.5mm PB Snip Heres a cross section - Those two don't quite match. You have the membrane above the counter batten. One reason for the counter batten can be to form a gap between membrane and batten so that any water that does get past the tiles can run down to the gutter and not pool above the battens. Its important on a roof with wooden battens because without it the membrane can be pressed against the batten. Pollen and other sources of dirt can collect above the batten and form a gunk/slime that seals any tiny gap that might exist. Eventually the timber batten can rot. Not an issue with metal battens? The way the tiles are lapped they depend on the interlock between adjacent tiles to be water tight. I also wonder if on one or two tiles the interlock broke without apparent damage to the tile. Link to comment Share on other sites More sharing options...
epsilonGreedy Posted January 1, 2021 Share Posted January 1, 2021 Condensation? Have you been plastering? Is the heating on this winter? Link to comment Share on other sites More sharing options...
Gone West Posted January 1, 2021 Share Posted January 1, 2021 10 hours ago, ToughButterCup said: The temperature of the air mass - from the south west warm, but wet - so little or no condensate. Freezing / very cold north wind promotes condensation ... drips The amount of water needed to travel through 300mm insulation would be a lot more than caused by condensation I'd have thought. Link to comment Share on other sites More sharing options...
ToughButterCup Posted January 1, 2021 Author Share Posted January 1, 2021 (edited) Yes Peter. So my theory is that there are two sources: a small crack in the tiles (rain), a rip or two in the felt, AND under-tile condensate taking unfair advantage of the holes. Thanks for the thought @epsilonGreedy, but no. The drip is localised to the edges of two sheets of PB. Doesn't mean that that's the source though. Does anyone think that a thermal imager might offer a clue to trace the leak back to it's source? There will be a temperature difference won't there..... idea? Edited January 1, 2021 by ToughButterCup Link to comment Share on other sites More sharing options...
Russdl Posted January 1, 2021 Share Posted January 1, 2021 15 hours ago, ToughButterCup said: As I write this, the damp patch has all but disappeared in the PB. That seems odd. After going through 300mm of insulation and taking two years to manifest it self you would expect there to be a lot of water up there so I'm surprised it seemed to dry out so quickly. I guess the drip is coming from directly below where the storm damaged tiles were? Could that be a coincidence and the drip is starting life somewhere else on the roof. I have to agree with @Temp re the roof build up. 9 hours ago, Temp said: One reason for the counter batten can be to form a gap between membrane and batten so that any water that does get past the tiles can run down to the gutter and not pool above the battens Link to comment Share on other sites More sharing options...
Russdl Posted January 1, 2021 Share Posted January 1, 2021 2 minutes ago, ToughButterCup said: Does anyone think that a thermal imager might offer a clue to trace the leak back to it's source? Thats got to be worth a go. Sorry, don't have one to lend. Link to comment Share on other sites More sharing options...
Pete Posted January 1, 2021 Share Posted January 1, 2021 Hi Ian, just another point. The guy who built next to us had a large portion of his ridge tiles crack. The roofer had foamed them on and they believe the roof/house settled (house t/frame)and the ridge tiles could not move and thus cracked. They have been replaced and all is well. I know you do not have a t/f house but just a another area to check how water may be getting in although a long shot. I realise if the membrane was doing its job water would not get in but ar the moment you need to find the reason it is getting in. Sorry it is happening 1 Link to comment Share on other sites More sharing options...
Onoff Posted January 1, 2021 Share Posted January 1, 2021 7 minutes ago, Pete said: The guy who built next to us had a large portion of his ridge tiles crack. The tiles crack themselves or the mortar joints between? Presumably this was a traditional build rather than a dry ridge? Link to comment Share on other sites More sharing options...
Pete Posted January 1, 2021 Share Posted January 1, 2021 The tiles cracked long their length and not the mortar joints. Link to comment Share on other sites More sharing options...
Onoff Posted January 1, 2021 Share Posted January 1, 2021 4 minutes ago, Pete said: The tiles cracked long their length and not the mortar joints. So a traditional roof with the tiles cemented on. Think a dry ridge is much more forgiving. 1 Link to comment Share on other sites More sharing options...
ToughButterCup Posted January 1, 2021 Author Share Posted January 1, 2021 (edited) Our ridge is dry. Ridge tiles double nailed ( yes, nailed)..... Under those tiles, there's a corrugated flexible ridge membrane. I have mislead you all about the roof build up: On top of the joists is a wooden batten that runs along the joists (25mm) [There's a 25mm gap between the top of the insulation and the top of the joists - 50mm gap in all] The there's the felt - with slightly slack trough to allow water to run to the centre of the gap between the joists On top of that is the metal batten which holds the metal formers which hold the ceramic tiles. I was incredulous when on our Piggery, a chippy foamed the tiles in place : and appropriately professionally cross. "How's the air going to circulate round the roof space?" I kid you not, this was the answer ..... "We don't worry about that oop 'ere . We allus duz that 'ere......" Edited January 1, 2021 by ToughButterCup Link to comment Share on other sites More sharing options...
ToughButterCup Posted January 1, 2021 Author Share Posted January 1, 2021 1 hour ago, Russdl said: ... Thats got to be worth a go. Sorry, don't have one to lend. Hmmm, looked at YT in relation to leak tracing and thermal cameras - it seems that it's not such a silly idea at all. January sales : I feel another tool beconing ... Anyone got a recommendation about thermal imaging cameras? Link to comment Share on other sites More sharing options...
Russdl Posted January 1, 2021 Share Posted January 1, 2021 (edited) 4 minutes ago, ToughButterCup said: Anyone got a recommendation about thermal imaging cameras? Didn't someone on here have one that attached to an iPhone? I'll see if I can find that... Yep, it's @AliG that has one, perhaps he can advise on its potential to trace that drip? Edited January 1, 2021 by Russdl Link to comment Share on other sites More sharing options...
Onoff Posted January 1, 2021 Share Posted January 1, 2021 FLIR is the name to conjure with. They do standalone cameras or ones than attach to your Android or Crapple phone. Nephew has one, really good. He has one of the C range. https://www.flir.co.uk/browse/professional-tools/thermography-cameras/?page=2 @Jeremy HarrisHarris had one, not sure if FLIR. 1 Link to comment Share on other sites More sharing options...
Onoff Posted January 1, 2021 Share Posted January 1, 2021 Jeremy had a Seek camera. 1 Link to comment Share on other sites More sharing options...
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