In previous articles, we defined different building solutions to prevent radon gas from entering into new buildings. In the case of dealing with the problem of radon in already built constructions, there are two ways of fighting it: ventilation or insulation.

Part of the information herein stated belongs to Doctor Borja Frutos Vázquez’s doctoral thesis, which was performed at the Polytechnic University of Madrid: Experimental study on both the effectiveness and viability of different structural solutions to reduce the concentration of radon gas in buildings.

Other data come from researches conducted by Synthesia Internacional on the S-35RGB-ECO polyurethane system, a system that works as a barrier against radon.

Building solutions to reduce radon gas inside an existing building

As we mentioned in previous lines, there are two methods of reducing radon gas inside an already built building: by ventilation and by installing an anti-radon barrier.

Ventilation methods against radon

The corrective measures that can be taken in the case of an already built construction regarding ventilation are the following:

• Natural extraction by central and external manholes.
• Natural extraction by central manhole.
• Natural extraction by external manhole.

Other measures considered as “non-corrective” but related to extraction are:

• Forced extraction (56 W) by 1 manhole (central).
• Forced extraction (80 W) by 1 manhole (central).
• Forced extraction (80 W) by 1 manhole (exterior).
• Pressurizing (80 W) by 1 manhole (central).
• Forced extraction (80 W) of the air from the basement (we remind you that the basement is one of the main entrances for radon into a building).

These measures reduce the presence of radon inside a building, as we can see in the following graph.

All measures related to ventilation present optimistic results regarding the reduction of radon gas

Anti-radon barriers made of polyurethane

As an alternative to ventilation, according to different studies, anti-radon polyurethane barriers are used. The results obtained are an example of the water-tightness action of this material.

This graph shows how, from an initial situation of presence of radon gas of 39,385 Bq / m3 in basement plant and of 6,855 Bq / m3 in first plant, a reduction is obtained to 1,446 Bq / m3 and 434 Bq / m3 respectively by applying a polyurethane anti-radon barrier of density 1,000kg / m3.

(And let’s not forget that, unlike air extractions or ventilations, polyurethane also offers thermal insulation function.)

Anti-radon polyurethane barrier: the case of S-35RGB-ECO system

The S-35RGB- ECO polyurethane system has an excellent behaviour as a barrier against radon gas according to tests conducted by Synthesia. Besides, it offers these advantages:

• It is ecologically formulated (not HFC), with an ultra-low GWP and it’s non ozone-depleting.
• It has a thermal conductivity coefficient of 0.020W / mK – 0.027W / mK.
• It has a classification of reaction to fire Euroclass E.

You can read our article about this system or download the video in which it is applied to insulate a warehouse’s roof in Norway: