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?

Sub-slab depressurisation / radon sump

Needs the grid

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

A site with elevated radon risk (a genuine, site-specific measurement, not assumed)

A pipe or sump under the floor slab that draws gas out of the soil and vents it outdoors. Radon, a natural radioactive gas found in some ground, is pulled away before it can seep into the house. It protects the household’s health where the ground contains radon.

Cost

Medium

Upkeep

Occasional

Skill to build

Intermediate

Lifespan

Fan: 10-15 years; the sub-slab piping/sump itself is effectively permanent once installed

Embodied carbon

Low

Space / material use

Low

Output timing

Continuous process

Skill to repair

Intermediate

Regulation (FR example)

Radon risk information is compulsory for buildings in category-3 radon-potential communes. Mitigation is not itself permit-bound, but is expected where measured levels are high.

Inputs

• Soil gas
• AC electricity

Outputs

• Soil gas

Compare the 2 ways to meet this need

Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.

• Sub-slab depressurisation / radon sump (This page)
  Can I use it? Not in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: No
  Choose it if radon is known in your area and you want it drawn away before it reaches the rooms.
• Sealed slab and vapour barrier
  Can I use it? Not in a flat · New build only
  What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: None · Change to daily life: None · Works without the grid: Yes
  Choose it if you are pouring a new slab and want a simple barrier against soil gas and damp.

Sources

• US EPA / general radon-mitigation industry durability consensus

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.