Is positive ventilation suitable for radon?

How positive ventilation works

A fan supplies air to the building, commonly drawing from the roof space. This can help change indoor air pressure and dilute radon. It differs from a sump, which acts beneath the building to extract ground air.

A property-specific decision

Suitability depends on the measured concentration, floor type, layout and existing ventilation. A product’s general indoor-air claim is not evidence that it will achieve a particular radon reduction in your home.

Consider the whole ventilation strategy

Ask how air enters and leaves rooms, how the system will be controlled and what maintenance is required. Discuss comfort, fan noise and energy use with the installer.

Measure the result

Keep the original report and arrange another test after the system is operating as intended. Discuss the next steps if the result still calls for reduction. Avoid relying on a guarantee based only on the equipment model.

What about condensation and mould?

Positive ventilation units are also sold to reduce condensation. The government’s guidance on damp and mould in the home says that if a home is inadequately ventilated, moisture cannot escape and is more likely to cause condensation, and that kitchens and bathrooms in particular need adequate ventilation. A unit that adds fresh air may help, but it does not replace working extractor fans where moisture is produced.

Treat the two problems separately. A radon test tells you whether the system has lowered radon; a home that stays free of condensation and mould through a winter tells you whether the moisture problem is under control. If mould keeps returning, look for a cause such as a cold spot, a leak or a broken fan. This guide explains why condensation and mould get worse in winter and what helps.