What is the average size of fireplace opening required to install an inset gas or electric fire?
A. The most common size of fireplace openings in the UK is 16″ wide x 22″ high. Most gas and electric fires are designed to fit into this size of fireplace opening subject to any depth restrictions. However most manufacturers either have a shallow or deep version of their fires or a spacer kit to decrease the fire depth by making it semi inset or fully outset in the case of electric fires or flueless gas fires.