1	List external walls to be insulated. Record each area and its depth (timber stud thickness) using the measurements shown in the diagram. Measure the doors and windows in each wall and subtract their areas from the wall area. Add the total external wall area.
2	Repeat the above process for each floor. For underfloor insulation record the depth of the floor joists. Add the total floor area.
3	Repeat for each slope. Add the total slope area.
	DO NOT deduct timber studs or joists from the wall, floor or slope measurements as this has already been allowed for in our calculations.