Insulation of a single skinned brick utility room

There is 2 ways to fix the problem .. 1stly you could use 50mm insulation backed plasterboard and skim.. 2nd you could fix 100mm external insulation boards and render the walls... Regards James...

Simply use 50 mm backed pir insulation board attached to the wall with dry lining adhesive. Then you loose minimal space and there’s no cold bridging at all.

Yes I would recommend aero-therm it’s 1mm thick and goes onto original plaster. It will keep reflecting the heat in and your walls are warm to touch .

Here are 3 options... 1) You could stud out the walls, fit kingspan (or similar) rigid board insulation & new plasterboard etc. This would reduce the room size a little, and therefore may not be you fav option! 2) assuming you already have plasterboarded walls, you could opt to fit insulation-plasterboard (either 30mm or 50mm) directly over the existing boarding. Effective and less of a disruption (although will usually still require plastering & new skirting) 3) Fit an insulation material (like Wallrock kv600 thermal paper) directly onto existing walls, plus a fibre liner & paint. Less disruptive, more economical & effective. Research the options and select the one you most favour 😊

As the previous builder said the most economic way is indeed to fix 50mm framework to accomadate 50mm celotex there is still cold bridging to tackle as it is only a single skin leaf. Therefore you should also employ a 25mm celotex vapour barrier to minimise spoilation caused by the studwork. Insulated plaster board would suffice but is expensive. Again cut accurately and seal with celotex tape. It is also best practice to paint the masonry with Thermoshield paint. This is the sort of paint we employ for caravans & warehouses were there is problems with heat control and works in conjunction with air conditioning. I hope this helps. Kind regards Mark