Insulating garage

[preecy]

Shortly after moving into our house a couple of years back we converted one half of a double garage into a usable room. The dividing wall down the middle of the garage was already in place. The builder went with cavity filling on the dividing wall and the new base wall were the garage door use to be (ie: under the window). We've noticed the converted room is a lot colder than other rooms in the house. I'm 99% sure the heat loss is coming from the other side the non-converted side of the garage as the two other walls are internal.

I've attached a couple of pics of the dividing wall to give you a better idea.

I know insulation was installed into the roof space of the converted room and a floating Kingspan subfloor was fitted. A big double rad was also installed along with an A rated double glazed window. I'm looking to fit some draft excludes around the door leading into the non-converted garage. What kind of insulation could a novice DIY'er fit to the dividing wall and roof space in the garage to improve heat loss.

 

[tomfe]

I am a little confused, the dividing wall was already there and then the builder added cavity insulation and then another block wall?
What about all the other walls?
Was this done to building regs?

 

[preecy]

No the wall dividing the double garage into two separate areas was already there. The only wall put in was the one the window sits on and bridges the gap where the garage door use to be. The builder cavity filled the dividing wall and the wall where the window is located. He then simply over-boarded & skimmed the area were converting into a room.

Yeah it was all done via building regs as the building control officer would sign it off until we provided the cavity insulation paperwork.

Attached some better pic of the garage before it was converted to give you a better idea of what im trying to explain, badly