A wooden fire surround must be a minimum of 18 inches or 450 mm away from the side or the top of the woodburner ie a gap all round of 18 inches or 450mm from the stove side to the inside point of a wood surround.
A wooden fire surround is a combustible material. The wood burning stoves and multi fuel stoves must be a minimum of 18 inches or 450 mm away from a combustible material such as wood.