The first task was to remove the lawn. There was 1,200 sq ft of it around the south, east and west sides of the building.
There are several ways to remove the lawn: solarizing (covering it in plastic so the grass bakes), layering (covering it in cardboard so the grass is starved of light), removing the turf using a sod-cutter, or using chemicals.
While chemicals is possibly the easiest and reduces weeds in future, I couldn’t bring myself to use them. So I rented a sod cutter. It took four days.