FoundationsforExtensioninBournemouth&Poole

Footings for extension work are not a fixed depth. Building control decides that on the day, based on what the new footing needs to carry and what the ground actually does once you're down in it. A single-storey extension on firm, consistent ground might need a shallower trench than the same extension on made-up ground or close to a tree, where roots and clay shrinkage push the required depth down further. That is why set-out and a site visit come before any digging starts, not after.

What foundations for extension work actually costs is driven by what's in the ground and what it takes to get to it, not by the square footage of the extension above. A straightforward trench in open ground with easy access for a digger is a different job to a hand-dug footing against a boundary wall, or one that turns up services that need diverting first. Muck away adds to that: spoil has to come off site, and how much of it there is depends on depth and reach as much as anything else. That is why pricing sits at survey rather than as a flat figure, and why the quote is fixed once it's been seen rather than adjusted once digging starts.

Cutting corners on foundations and footings does not show up straight away. It shows up a year or two later, as cracked brickwork above a footing that was never taken down to a firm base, or as water sitting against a wall because nothing was built in to move it away. Digging footings to the depth the ground actually calls for, inspecting before the pour, and getting drainage and services into the ground while it's still open is what stops that happening. It costs the same either way. The difference is whether it is done once.