bmj1

Is a flat roof involved? This is the one area I got burned on when our main contractor did the same..

Or could use this for our ceiling, below the joists ? (Taking special care to seal any penetrations)

Or could I apply the VCL from underneath the joists? A bit more work, but feasible ?!

Just came across this thread: VCL paint from below as another possibility?

Maybe... What kind of structural problems are you concerned about ? If the whole condensation issue is localised and contained above the deck I'm not sure what issues you foresee?

Polythene plastic loose laid was used instead of specified VCL. Spoke to a specialist flat roofing company today who advised me it's just a matter of time until it fails... But welcome alternative thoughts !

Hi all, I've got a newly built warm flat roof that I've been advised is likely to fail at some point over the next few years due to an error in the build-up / interstitial condensation. Instead of replacing it today, I'd prefer to try and get a few years of use out of it, and rebuild it down the road when finances are hopefully a bit looser.. Any thoughts on some kind of moisture meter I could install, and where I should locate it ? I.e. would between the joists be sufficient ? We'll be running services between the joists and then plaster-boarding below

Thanks for the feedback.. It's dot and dab, so I've assumed some kind of gap behind the blockwork. Does that make sense ? I don't want to go so high with the thickness, to conserve floorspace ! So to confirm, no need to worry about a VCL, even if the insulated plasterboard has no foil component ?

Not committed, looking at 17mm PIR bonded to 9.5mm plasterboard, as the insulated plasterboard. I'm a little nervous about the dew point also. And I do think we have to assume there will be some gaps between the rockwool locally in a few areas... Does that make sense ?

Ok thank you. So no risk of interstitial condensation?

Wall build up 100mm Brick 50mm cavity 100mm rockwool slabs 100mm concrete block Insulated plasterboard (not yet built) Does the insulated plasterboard require an integrated VCL ? (assume dot + dabbed).

I looked at this product myself but couldn't find third party verification/certification of the claimed conductivity.

Exactly. The other key point of aerogel is that it is vapour permeable, making it suitable for retrofit in older buildings. Having looked at aerogel for wall looking, we're now making use of an insulated plasterboard with just 17mm of PIR bonded to 9.5mm of plasterboard.

Can you provide more information on the problem you are trying to solve?

Okay, I think this is very bad, but want to get opinions: We have a finished flat roof: 100mm warm deck above, and for some reason, 25mm between the joists ?! The insulation between doesn't appear to be pressed up tight against the plywood above (which I understand is the thing to do when doing this), but instead, there is a gap due to the piece of wood running across above the joists I'm concerned about interstitial condensation Is the only sensible option is to remove the 25mm insulation between, and live with 100mm insulation above... and make up on the SAP elsewhere ?

As per the topic, is there any feasible way at all to add an extra row of tiles ?

That's totally fine. 10% + a fitting charge is totally reasonable. And I'll handle the cashflow. I'm just wondering if this is crazy talk in principle?

Understood. But paying tens of thousands feels ludicrous to me for pvc sash windows..

OK, so: I've sourced the windows we like, and negotiated trade pricing with the window manufacturer (which I've had confirmed is the same as any fitter will get). ~35 PVC sash windows in total. We're in North London Am I crazy to think we can organise measure & fitting of these, and ask our main contractor to order the windows for us supply-only (to save us fronting the VAT) ? When I've tried to source these supply+fit the mark-ups have been really crazy...

Hi all, When is the earliest I can use a thermal camera on our project to check for issues with gaps in insulation, etc ? E.g. once all windows are in ? Many thanks in advance

I've got space for insulated plasterboard internally, just wondering if a risk of condensation?

This is a very clever idea. Would need the planning conditions worded right. The only thing I don't like is it might complicate the demolition (do you really want a 23 tonne digger anywhere near your brand new foundations?)

Hi all, We've got some rooflights built like this: I'm not entirely sure on the insulation in the upstand (if any). Is there any reason not to use a insulated plasterboard here (17mm PIR + 9.5mm plasterboard), in order to reduce the thermal bridging ? (My concern is of creating interstitial condensation)

Awesome, thank you !

A constraint. But I'm ok with it. I'm planning to have each room zoned with heatmiser. Tbh - instant response sounds good to me. I'm not sure I understand why we would want to wait an hour to feel the benefit of the heating ?