Reverse the pressure, and the gas stops coming in

Basements, slab-on-grade and most homes with a concrete floor.

One or more suction points are cored through the slab, a small pit is excavated beneath it, and PVC pipe is run from the pit to a continuously running fan that discharges the soil gas above the roofline. The fan holds the soil beneath the slab at a slightly lower pressure than the room, so gas travels down the pipe instead of up through the floor.

• The most common and usually the most effective method
• Usually one suction point; larger or divided slabs need more
• Diagnostics confirm pressure field extension before anything is cemented in

Homes with a crawlspace over exposed soil.

A reinforced vapor barrier membrane is laid over the soil and sealed to the foundation walls and any piers. A suction pipe is drawn from beneath the membrane to the same kind of exterior fan and riser. The membrane stops soil gas entering the crawlspace and the fan draws it away from underneath.

• Membrane is sealed, not merely laid down
• Crawlspace vents are usually closed and the space conditioned
• Often paired with sub-slab work in split-level and stepped homes

Homes with a perimeter drain tile or a sump pit.

Where a drain tile already surrounds the footing, it can be used as the collection point instead of coring the slab. A sealed, gasketed sump lid is fitted and the suction pipe is drawn from the pit. It reaches the same soil gas with less cutting and fewer visible changes to the floor.

• Requires a genuinely sealed sump lid to work at all
• Keeps the basement floor intact
• Water management and radon control are designed together, not against each other

Homes with hollow masonry or block foundation walls.

Hollow block walls behave like chimneys for soil gas and can carry it upwards into living space. A suction point is drawn from the wall cavity itself, sometimes combined with slab suction, so the wall voids are held under negative pressure too.

• Common in older homes where the wall is the main entry route
• Usually combined with a slab or drain-tile suction point

Very tight homes, or where depressurization is impractical.

A balanced heat recovery ventilator introduces and exhausts air continuously, diluting indoor radon and holding the building near neutral pressure. It is a dilution strategy rather than a source-control strategy, so it is used where the soil pathway cannot be closed, or alongside depressurization.

• Not a substitute for source control in a home with high levels
• Also improves air quality in tightly built modern homes