Dimensions of solid non-combustible walls adjacent to hearths

Location of hearth or appliance | Solid non-combustible material Thickness (T) | Height (H) where the hearth abuts a wall and the appliance is not more than 50 mm from the wall | 200 mm | not less than 300 mm above the appliance and not less than 1200 mm above the hearth where the hearth abuts a wall and the appliance is more than 50 mm but not more than 300 mm from the wall | 75 mm | not less than 300 mm above the appliance and not less than 1200 mm above the hearth where the hearth does not abut a wall and is not more than 150 mm from the wall | 75 mm | not less than 1200 mm above the hearth Note: There is no requirement for protection of the wall where X in Diagram 3.13 is more than 150 mm.