I have a converted garage that is joined to my neighbours by a concrete block wall. My neighbours garage is being used as a garage and has no insulation anywhere and the wall is bare. On our side the wall was plasterboarded but the room is freezing. So I took some of the plasterboard down and I can feel the breeze coming through the block - both at the cement joints and also in the main area of the block. I have decided to pull all the plasterboard down and fix the problem as the room is currently useless. Any suggestions on how to make a concrete block wall like this airtight and warm? I know plastering is an option but can I then apply insualted boards on battens or dabs? Can I apply an airtight membrane before the battens? Any suggestions would be really appreciated. Also on any suggestions, do you reckon I could do it myself as a diy'er?