AH92 Posted January 12, 2023 Share Posted January 12, 2023 I live in a new build Taylor Wimpey property that was built 5 years ago. I had my loft boarded about two years ago and then recently went into my loft to find that all my stuff was covered in mold and the sagging was wet and the point where some sort of taping was applied between the overlaps. I have since purchased vent flaps and moved insulation that was blocking ventaltion into the property. I have noticed that my timbers frames are really wet at the point where the black sagging touches the joists. I am really struggling to know if this is due to condensation or another issue? please see pictures Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 Picture showing wet joist Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 Another pic Link to comment Share on other sites More sharing options...
Radian Posted January 12, 2023 Share Posted January 12, 2023 45 minutes ago, AH92 said: I have since purchased vent flaps and moved insulation that was blocking ventaltion into the property. It certainly looks like condensation and should clear up with improved ventilation. I don't understand the first photo though - what's the black membrane coming just past the rafter? The grey stuff looks to be breathable but I don't know what the black stuff is. A point about your boarded area: is it laid directly on top of the truss chords (horizontal timbers spanning the top of the house)? 1 Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 The black is the water that has gathered on the grey material. The material touches a joist and when pushed back is full of water and therefore makes the material look darker. the loft boarding was fitted by a tradesmen who using plastic loft legs and installed the boarding onto these. The insulation is still laid underneath the boarded area. I did some further investigation and that Taylor Wimpey had placed insulation in the eaves of the roof. When I removed this, I could see more daylight coming through. I am unsure if this has contributed to the problem. Link to comment Share on other sites More sharing options...
Radian Posted January 12, 2023 Share Posted January 12, 2023 3 minutes ago, AH92 said: The black is the water that has gathered on the grey material. Oh, I wasn't expecting anything quite so saturated. What sort of outside temperatures were there when you took these photos? There's a shocking amount of condensation that will form in a cold loft. I'm sorry to say it's never going to be a good place to store anything. Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 The temperature outside was 5 degrees when these pictures were took this afternoon. It rained just before I took the pictures. as you can see from some of the pictures, the water seems to be more concentrated in between the layers of the grey material (where it overlaps) which appears to be held by some sort of tape. I know this because I had to push away the tape when inserting loft vents. The areas where the timbers touch the grey material are also highly saturated. Link to comment Share on other sites More sharing options...
Radian Posted January 12, 2023 Share Posted January 12, 2023 7 minutes ago, AH92 said: I did some further investigation and that Taylor Wimpey had placed insulation in the eaves of the roof. When I removed this, I could see more daylight coming through. I am unsure if this has contributed to the problem. It depends on the location of the ventilation apertures. If they're openings in the underside of the soffits then insulation might have compromised them. If they're like trays sat on top of the fascia boards, under the first few rows of tiles then so long as you can see the opening at the top of the tray above any insulation then it won't matter if the eaves a fully stuffed. All I can see is a black strip low down - is that a tray or more saturated membrane? Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 They are trays. I have one tile vent installed and have now put in 10 felt lap vents to see if this eases the condensation build up? do you have any other tips/suggestion/thoughts as to why there is so much condensation build up in a new build property? Link to comment Share on other sites More sharing options...
Radian Posted January 12, 2023 Share Posted January 12, 2023 The condensation seems to be forming on the back of the roofing battens (regular horizontal rows). That would make sense as they're presenting a cold surface tight to the membrane and also blocking the breathability of the membrane in that place. Fairly normal. What's a bit puzzling is how this is all happening at 5oC. While it will certainly be below the dew point for air in the loft, the amount of water vapour up there is considerable. Cold lofts will occasionally see conditions where the elements conspire to create a significant amount of condensation but over the course of a year, it will generally work out. You may just have decided to look at a bad moment (prolonged moist, warm air mass suddenly replaced by a cold spell - look at local weather stations to see what's been going on lately) or there's some serious air leakage from below (unsealed extract or plumbing pipes, downlighters in upstairs rooms, poorly sealed loft hatch). Link to comment Share on other sites More sharing options...
AH92 Posted January 12, 2023 Author Share Posted January 12, 2023 Upon inspection, I noticed that our soil pipe was not fitted with an air admittance valve for the entirety of the 5 years since I moved in. I also noticed that the extractor fan ducking hose had not been secured with anything. It was merely pushed onto the venting pipe. I have now fixed these issues but I am unsure how severely this could have impacted moisture levels in the loft. This is the first time since moving in, I have noticed such drastic water build up in the loft. The hatch seems to be fairly secure when closed. Link to comment Share on other sites More sharing options...
Radian Posted January 13, 2023 Share Posted January 13, 2023 9 hours ago, AH92 said: Upon inspection, I noticed that our soil pipe was not fitted with an air admittance valve for the entirety of the 5 years since I moved in. How is the stack terminated then? Presumably you noticed this when looking around in the loft so was it open to the atmosphere? If it was, apart from the smell, it'd be a massive input of water vapour when carrying bathwater! Link to comment Share on other sites More sharing options...
AH92 Posted January 13, 2023 Author Share Posted January 13, 2023 9 minutes ago, Radian said: How is the stack terminated then? Presumably you noticed this when looking around in the loft so was it open to the atmosphere? If it was, apart from the smell, it'd be a massive input of water vapour when carrying bathwater! I have had an AVV fitted on it since the discovery that it was completely open and venting into the loft space. Link to comment Share on other sites More sharing options...
johnhenstock83 Posted January 13, 2023 Share Posted January 13, 2023 the eaves of your roof should allow daylight in all round. that will provide enough ventilation and keep your roof dry, even in extremely cold weather. we have a similar setup on a 1950s house, roof is bone dry all year round, despite being properly insulated and boarded. just clean the soffits every now and then and make sure there's a 5" gap between whatever insulation you have in place and the roof. the wet joists will be fine, it doesn't look like permanent damage, they'll dry in no time with extra ventilation. 1 Link to comment Share on other sites More sharing options...
Radian Posted January 13, 2023 Share Posted January 13, 2023 41 minutes ago, AH92 said: I have had an AVV fitted on it since the discovery that it was completely open and venting into the loft space. What's the timescale of fitting the AAV relative to the date you took your photos of the condensation? With so much water vapour entering the loft from emptying baths etc. I would expect it to take days or weeks to get humidity levels back to normal. 1 Link to comment Share on other sites More sharing options...
AH92 Posted January 13, 2023 Author Share Posted January 13, 2023 Thanks For the support Link to comment Share on other sites More sharing options...
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