CH_18

Just about to purchase either VCL or a Vapour barrier (polythene). Anymore thought on this before I order? If I'm foil taping anyway shall I just stick some polythene up instead of a controlling layer?

It will be Welsh Water. I understand the concerns with a building/extension but is a non load bearing wall allowable?

Hi all, Just coming round to doing our drive and entrance on our new build and would like to build an entrance wall over a main sewer, is this allowed? It's not really a permanent structure and could be knocked down easily if it was required. I've read the building over sewer guide but it only mentions houses/buildings/extensions not boundary walls? Thanks

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?

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?

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?

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?

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?

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 🤦

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?

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.

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.

*laying flat

Ok thanks for the advice What about in the ceiling between joists? I suppose because the insulation is laying flate it doesn't need the structural properties of the acoustic stuff so is normal loft/mineral roll on here? Looking to put in 150mm.

Yeah looks like a decent middle of the road option, nearly half the price of RWA 45. Where did you get yours from @Chanmenie?

Linked here https://pinksinsulation.co.uk/product/ursa-acoustic-partition-roll-a-p-r/

Thanks gents, appreciate the advice Has anyone used URSA acoustic roll? Seems like a middle of the road option at 22kg density?

I must have read nearly every post on here regarding sound insulation and I'm still none the wiser. In our timber partition walls (89mm CLS) I was planning on filling with 75mm Isover acoustic roll or RWA45 then sound boarding both sides. I've since read on here that the denser acoustic stuff has no real benefit compared to normal loft roll? There was a link to some study posted here which showed the results. Is the denser acoustic stuff worth the extra premium? Also does anyone know of a cheap place to get some? My BM only stock 100mm and 50mm non acoustic, just loft roll 🙄

I don't think I can chop out a row of bricks and set a sill in because the cavity is concrete filled, so even if I do take a row out I can't set a sill back far enough under the door 😔 Annoying

Yeah I've seen that posted here a few times. That's got a sill by the looks of it 🙄

I think I know the answer to this. Had our front door fitted this week and to my suprise was fitted without a sill? Door has been installed within the cavity to avoid thermal bridging but now without the sill exposes a possible water ingress issue. The cavity below the door is lined with DPM and concrete filled so is sitting on this. Before they fitted the door I had the DPM pulled up at the front and lapped backwards behind the door so the door could sit on this but they trimmed it off flush at the front?? I queried the fitting at the time of install and they assured me it was correct, it was for thermal bridging and a sill couldn't be fitted for the level access for regs? The rainwater running down the door can now flow behind the visible DPC and soak the cavity filled concrete? 1. Is this wrong and 2. How do I fix it?

Cheers guys, my question was more towards the theory, if you end up taping the joints of the aluminium foil back you essentially seal the envelope due to the high SD value of aluminium foil? So putting a controlling/slow release VCL with an SD value of say 10m in would be deemed pointless, am I right in saying that?

Spoke to my BCO, who has said that he will not accept taping the joints of my foil backed PIR in my sloping roof as an acceptable vapour control layer. He has asked for an additional VCL. 🙄 I have 60mm over the top of the rafters which I will go ahead and tape the joins anyway, but is there any point in me buying a VCL or should I just put polythene (a vapour barrier) over the top? Typical SD value of foil tape is 200m so a "controlling" layer will be of no use anyway? The controlled release will just be sealed by the foil anyway? Thanks

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 🤷🏼‍♂️

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 🤷🏼‍♂️