Loft Conversion Insulation Advice

photonic69

Hi all,

Any buildery types that can advise on inproving the insulation in our loft conversion? We had it done about 20 years ago and the majority of the insulation above the plasterboard was Tri-Iso Super 9 Multifoil.

It's always cold in winter up there and my wife uses it as her office now she works full time and 3days a week WFH.

What options do I have to improve it to make it retain heat better?

Option #1 Overboard existing with 55mm Insulated Plasterboard and reskim and redecorate. TBH it needs new paint as it hasn't been done since 2004.

Option #2 We were looking at getting the roof retiled at some point. We had it last done in 1996 using a lot of the original tiles from circa 1902 and now quite a few are spalling. If we did this we could get them to put 50mm Celotex between the rafters and leave a 50-70mm airgap. Also add eave and ridge vents.

Obviously #2 is going to cost waaaay more but what would work out best/most efficient long term in light of continually rising energy costs?

TIA

oxoman

P69 we had our 1896 house converted in 1999 and suffered the same problem. We actually had 50mm polystyrene in between the roof trusses and foil backed plasterboard. Since then we've had the original tiles relayed as they were nearly as good as new. We took the opportunity to have celotex fitted and tbh it was a lot better especially in summer. We did consider putting another insulated plasterboard board layer in but we were advised we may have to beef the roof up depending on the plasterboard weight. We used a 50mm polystyrene between ceiling joists and currently 300mm fibreglass on top. Just be aware decent clay tiles will way outlast concrete ones. Concrete tiles will last around 40yrs against 100 plus for decent clay tiles. Our biggest problem has been keeping the rooms cool in summer tbh. Since we replaced the glazing units in the velux windows to some special coated extra thick ones and decent blinds it's made a difference. We also took all the self closers off the doors as soon as planning passed it off, so we get the warm air from downstairs. Shh don't tell them. Might be worth finding a specialist, but not these flyby night grant type ones.

rjsterry

Option 2 is the better bet. Insulate between and over the rafters and then a good breathable sarking membrane, battens and tiles is the right way to do it. It's probably not helpful but I am still not sure how multi foil insulation ever got its BBA Certificate. I just don't think it's real world performance is anything like what is claimed. And it only needs one un-taped joint to be bypassed.