Colder extension

[yottie]

We have a 1971 bungalow with cavity wall insulation (foam), the loft is insulated up to standard. In 1980 an extension was added to the side, this measures about 13' square. The roof is flat and felted, it has no windows except aluminium sliding patio doors, I'm assuming there is some wall insulation in the three out-side walls, it has one radiator. The problem is the big difference in the temperature in this extension, some 7 degrees less than the main building, both facing South. Am wondering what is the most cost effective way of tackling this difference, is it worth replacing the patio doors, is there some way I can line the ceiling from inside etc. Would welcome any advice.

 

[TheVictorian]

If there is enough height you could perhaps overboard with insulated plasterboard? 100mm would be great, 50mm would still be a lot better than nothing. A new set of A rated patio doors would also probably help.

A bigger radiator will also get more heat into the room, although this might not be needed if you complete the above.

 

[kbdiy]

Building Regs in operation at the time it was built were quite scant on insulation by today's standards so your assumption about the walls being insulated may not be correct unless you have positive evidence to the contrary.

Might be worth getting them checked if you are unsure, plus of course, anything you can do to improve the roof would be of benefit too.