Fear for health by moisture problems

Mould in a house is often a big frustration. Finding the right cause is imperative for a good life quality.

Mould of a considerable amount is unhealthy. It is very necessary to handle this problem.

Problem:

The owner of the house feared for his health after problems occurred 5 years after a renovation.

Investigation:

With measurements, examination and a tour we have determined that there are serious moisture problems in the house. The most areas around the windows, walls and floor measure relatively dry. Except below the level of the moisture membrane where the wall is directly in contact with the floor plate.

The façade is tested on porosity with a Karsten tube test. This appeared to be very porous because of which the outer cavity wall measures soaking wet.

Conclusion:

Because of the missing ground level zone membrane, rainwater runs through the saturated ground level zone into the crawl space. The result is a very high underlying vapour pressure. This vapour pressure goes through the complete building and condensates on the coldest spots. The vaporisation and absorption of this moisture costs 20 - 30% extra on heating. There are way to little ventilations provided for the high vapour presure of the wet crawling space. Furthermore, because of the present T-ventilation it can rain directly into the crawling space.

Rainwater gets into the cavity wall. And as a result dew point condensation occurs in the cavity wall by temperatures of 14,2°C and lower. That's why there are white residue and lichens on the façade.