Protection against radon gas in existing buildings

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 previously, there are two methods of reducing radon gas inside an already built building: by ventilation and by installing a barrier against radon.

Ventilation methods against radon

The corrective measures that can be implemented in the case of an existing building 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:

These measures reduce the presence of radon inside a building, as it can be observed in the following graph:

anti radon

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


Polyurethane barriers against radon gas

As an alternative to ventilation, different studies have proved the value of polyurethane barriers as a solution against radon gas. The results obtained are an example of the watertightness provided by this material.

This graph shows how, from an initial situation of presence of radon gas of 39,385 Bq / m3 in the basement and of 6,855 Bq / m3 on the first floor (number 00 of the graph), a reduction to 1,446 Bq / m3 and 434 Bq / m3 is respectively obtained by applying a polyurethane anti-radon barrier with density 1,000kg / m3 (number 10 of the graph).

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

radon building


Polyurethane barrier against radon gas: 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, 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:

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Fire response of polyurethane: false myths

Polyurethane systems surround our daily lives, however, we still hear some voices that call into question the response of polyurethane in case of fire. 

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Technical Data Sheet Poliuretan Spray S-35RGB/ECO