Transfers load below the clay-active zone (min. 0.8-1.2m per exposure); individually adjustable/relevelable.
Cost
Medium
Upkeep
None
Skill to build
Intermediate
Lifespan
50+ years (steel/concrete piles); relevelable rather than replaced on failure
Embodied carbon
Medium
Space / material use
Low
Output timing
None
Skill to repair
Intermediate
Regulation (FR example)
Part of the structure or footprint: covered by the building permit (permis de construire) for a new dwelling. Rural sites are additionally constrained by the commune's PLU zoning, outside a constructible zone, a new dwelling is generally refused.
Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.
What your site needs
Clay-active or unstable soil where a slab/strip footing would need to resist rather than sidestep movement
Inputs
none
Outputs
none
Sources
Foundation engineering industry consensus (screwed/deep-pile foundation manufacturer and geotechnical guidance)
What this page does not tell you
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.