I would like to have an electric fire in our main room to take the chill first thing in the morning. It is a moderate room and the fire I would like is an electric stove which has a depth of 340m/m. I do not want the fire to protrude into the room by 380m/m so I thought I could knock a hole in the exsisting wall and make a fireplace to sink the fire into. It is an external wall with no chimney breast and is made up of 15m/m plasterboard, 200m/m breeze block 40m/m cavity then the outside bricks. So I would cut through the plasterboard and breeze block making a fireplace of approx 200m/m depth to allow the fire to sit inside. I would face the inside with plaster board and use expanding foam to seal around. would this create a cold point as there is only the outside brick wall between the outside and inside.