As a rule of thumb you should calculate:
1 screw pile footing per m2 for single beam layer and 1 screw pile footing per 1,5 m2 for double beam layer.
If you are mounting 1 or more of your bearers on the house wall, you can subtract about 0,5 footings per running meter of bearer.
For light sheds, playhouses and similar:
1 screw pile footing per 0,75 m2.
Like with all other types of footings and foundations, your screw pile needs depends on a number of different parameters of your project. If you are the least uncertain of what screw pile footing dimension to choose or how many you need, just fill out the relevant form below and we will calculate your project free of charge: