minimum depth of foundation:– minimum depth of foundation is around 5 feet for a small residential building from ground level or at least 1.50 times the width of footing. In cold climates the depth of footing is Kept at a minimum of 1.50m below surface because of possible frost action.
How do I know my foundation depth?
The depth of foundation is determined by the:
- Plasticity index of soil.
- Water demand of the tree.
- Mature height of the tree.
- Distance of relevant tree to nearest part of foundations and distances elsewhere if stepping foundations.
- Allowance for climatic conditions.
How deep should foundations go?
Generally a depth of 700mm is acceptable, as long as the ground has adequate bearing capacity. If the water table is high (for instance if the gravel is submerged), the bearing capacity will be halved, so it's important to keep the foundations as high as possible.
