Systems guides

The system a house needs is decided by its foundation. A basement or slab gets sub-slab depressurization, a crawl space gets sub-membrane depressurization, and a hollow-block wall can be drawn down through its own cavities. Mixed foundations usually need more than one suction point — which is why the quote for a house with a basement and a crawl-space wing is not the same as the quote next door.

Sub-slab depressurization

The default. A core through the slab, a small suction pit in the soil beneath, PVC pipe to a fan, and a vent above the roofline. Installed band: $800–$2,500. It works on basements and slab-on-grade floors, and it is the system most bids describe.

Sub-membrane depressurization

A crawl space has to be covered before it can be depressurized. A reinforced vapor barrier is sealed to the walls and piers, then a pipe draws from beneath the membrane. Installed band: $1,100–$3,000. An unsealed membrane is the most common reason a crawl-space system underperforms.

Drain-tile and sump-pit tie-ins

Slab-on-grade houses often have perimeter drain tile and a sump pit. If the pit can be sealed with a gasketed lid, it can become the suction point: $800–$2,500. An open pit is a hole in the pressure boundary and cannot be used without a lid.

Block-wall depressurization

Hollow concrete-block walls form a ready-made suction field. The installer seals the top of the wall and draws from the cores: $1,000–$3,000. It avoids a slab core and keeps the pipe out of the living space.

Passive systems and activation

New construction can include a passive system — gas-permeable layer, vapor barrier, sealed vent pipe, junction box — for $500–$1,500. It relies on stack effect instead of a fan. If a test after occupancy reads at or above 4 pCi/L, adding a fan costs $300–$900 and converts it to an active system.

How the choice is made

The foundation decides the family of system; the site visit decides the details: how many suction points, where the pipe runs, whether the roof penetration is straightforward, and whether the electrical panel has capacity. A bid that names no suction-point count is a price, not a design.

Read the full foundation guide →

Frequently asked questions

What system works for a basement?

Active sub-slab depressurization: a pipe through the slab with a fan drawing soil gas to a roof vent. Installed cost is typically $800–$2,500.

How do you mitigate radon in a crawl space?

Sub-membrane depressurization: a sealed vapor barrier over the dirt floor, with a pipe and fan drawing from beneath it. Typically $1,100–$3,000 installed.

Can a passive system be upgraded later?

Yes. If the passive pipe was installed correctly, adding a fan costs $300–$900 and turns it into an active system without opening the floor.