Mould contamination of a newly constructed apartment block

It is a fact that just because an apartment or a house is newly build the owners do not have to deal with issues. In fact, an aged property with no history of dampness or leaks has probably less indoor air quality issues than a brand new building. I have visited a relatively newly constructed apartment building which was suffering from chronic mould problems. The developer has resolved to redecorations and items replacement rather than to finding out what was happening in the building as a whole. After some of the occupants have had third set of redecorations and replacements I was approached to formally investigate the building in identify the root cause of the problem.

mould testing

I have carried out mould inspection of the building with detail moisture testing and elements of intrusive inspection. A part of the mould surveys was also the evaluation of the existing indoor air quality in respect to the occupants’ health. The apartment I have visited was located on the ground floor of a larger residential building. The apartment consisted of an open plan kitchen-lounge area, two bedrooms, bathroom and a boiler cupboard. The concrete floors, with the exception of bathrooms and kitchen area, were carpeted with modern fibre carpets with foam underlay. The bathroom had ceramic tiles to floor and kitchen had laminate flooring. The internal partition walls were made of 12mm paper-backed plasterboard with mineral wool cavity insulation.

mould survey

Prior to any destructive inspection I have carried out mould sampling. It is essential to carry out the indoor air quality sampling before disturbance of construction materials as such disturbance is likely to amplify the spore count resulting in incorrect and biased measurement. My mould sampling showed that the total concentration of mould spores in the apartment was lot higher than the existing environmental background. My measurements also showed that the collected samples contained moulds closely associated with water damage in buildings such Chaetomium, Stachybotrys and Penicillium/Aspergillus group. This was strongly indicative that indoor sources of mould were present. I have collected mould samples from visible growths and confirmed the presence of Chaetomium, Stachybotrys and Penicillium moulds.

mould testing

I have inspected the apartment for signs of elevated moisture in construction materials. All plasterboard ceilings, plasterboard walls and skirting board showed consistent and uniform levels of relative moisture. The material relative moisture levels were low and below the levels fungal growth can be supported.

mould sampling

 

The relative moisture measurements of concrete base plate show elevated moisture level in the living room and living room cupboard areas which extends to the outside under-stairs cupboard. The relative moisture level measurements show approximately 30% variation in moisture content in different areas of the concrete base plate. The absolute moisture content of the concrete was not evaluated. Intrusive inspection of the wall cavity between showed that the internal wall cavity was clear of mould contamination, and that the exposed materials had very low moisture content. Mould contamination was found to the skirting board and plasterboard. The skirting boards showed signs of water damage, swelling and delamination suggesting active saturation with water, rather than absorption from humid air.

mould inspection

I have also carried out measurement of ventilation rates and compared them with the relevant regulatory guidance.

Following my mould inspection I have concluded that at the time of my inspection the apartment was not affected by active water leaks. The observed mould contamination resulted from a one off leak to the boiler which saturated the mineral wool insulation and wall. I have also concluded that under normal living conditions the existing ventilation in the apartment was not sufficient to control internal humidity levels.

The resulting mould contamination in the apartment was most likely caused by a combination of several issues. The contributing factors to intermittently high humidity were likely to be insufficient extraction capacity of the bathroom ventilation, possibly intermittent minor leaks and incomplete dryness of the concrete base. Combination of these likely moisture sources and relative coldness and lack of air movement in certain areas in the apartment resulted in water condensation from ambient indoor air and subsequent mould growth.

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Hi, I have been working in my job as an Indoor Air Quality Investigator for a number of years and decided to share my experience with you. You can find lot of related information on my website toxic black mould
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