Add the length of all outside walls for the perimeter. Multiply by the average wall height. Keep normal doors and windows in the measurement.

Use measurements taken at ground level or from your plans. For irregular shapes, add each wall’s length × height, then choose “I know the wall area.”

A conditioner for chalky or porous masonry that helps prepare the surface for paint. Vidar will confirm whether it suits your walls. Selecting it adds application and a material allowance.