Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?
Deep pile / screwed-pile foundation
Passive · New build only
One of 2 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
What your site needs
Clay-active or unstable soil where a slab/strip footing would need to resist rather than sidestep movement
Long piles, driven or screwed deep into the ground, that carry the house instead of a shallow footing. They reach below the clay that swells in wet weather and shrinks in drought, so the house stays put when the surface soil moves. Each pile can be adjusted to bring the house back level.
Build it
This is contracted work rather than a self-build.
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.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Deep pile / screwed-pile foundation (This page) Can I use it? Not in a flat · New build only What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: None · Change to daily life: None · Works without the grid: Yes Choose it if you want the house fixed and level on clay that swells and shrinks, with nothing to re-level afterwards.
Skid or point-support foundation Can I use it? Not in a flat · New build only What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: None · Works without the grid: Yes Choose it if you want a cheap, light foundation that lets the house ride on moving clay and be packed back level.
Sources
Foundation engineering industry consensus (screwed/deep-pile foundation manufacturer and geotechnical guidance)
Limitations of this page
We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.