How to retain heat from outside walls?

[ibuk]

Hello,

I've got a new extension which is currently being plumbed and eventually it will be plastered etc. I have a question regarding heat retention for outside walls. All the new radiators are on outside walls and the new bedroom upstairs has three outside walls. On two of these walls I have some large radiators which are supposedly 7,300 BTU each, in order to retain the heat would it be an idea to install plaster board with foil backing on all the outside walls or will this make no difference? I will be using foil backed plasterboard on the upstairs ceiling but not sure if this would make a difference on the walls.

Please let me know your thoughts.

 

[HERTS P&D]

Make sure you have at least 350mm of insulation in the loft above.

Andy

 

[dcawkwell]

If the extension is built to modern standards the levels of insulation are
high and therefore you don't need to worry about further insulation.

 

[ibuk]

It is a new build and the cavities have 100 mm of insulation and currently the roof space will have 270 mm which can be bumped if necessary.