Even if ground conditions were perfect at one inch below the surface, you would still be wise to set them at a depth simply for protection and stability.
1m is a default setting that usually guarantees decent ground. I have built four or five extensions per year for the last 8 years or so and it is rare that the ground is not good enough at standard depth.
Building control do sometimes allow a shallower dig provided the conditions allow.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local