Mould contamination due to leaky bathtub

Minor service leak can sometime results in serious problems in particular if they are ignored or not fixed properly. I have recently visited an apartment where a minor water leak from a bath waste pipe resulted in a major mould contamination of the internal cavity walls. The apartment I have visited  was located on the 5th floor of an inner city apartment complex. The flat consisted of two bedrooms, living room, kitchen, bathroom and a store room. The partition walls were mainly plasterboard with insulation infill and ceilings in the whole property are plasterboard.

The property occupied only for a short time when the owners noticed that something is not right. They have noticed strong odours in the bathroom and the kitchen which could be described as damp and fungus related. Fortunately at the time of my inspection the occupants did not currently suffer from any adverse health symptoms. Prior to them moving into the property there was a long term water leak in the bathroom area which has caused a significant deterioration of the bathroom floor. The water leak was identified and repaired prior the commencement of the occupancy.

mould in kitchen

I have carried out a moisture survey of the property and identified a minor water leak under the bathroom which caused significant deterioration and fungal rot to the underlying timber floor. I have noticed the presence of live and active macroscopic wood rotting fungi directly under the areas of the leak.

mould in kitchen

I have also investigated the moisture content of the partition wall between the bathroom and kitchen which appeared to be normal. Unfortunately also in this area I have noticed a significant mould growth on the external and internal sided of the plasterboard panelling. The total extent of the mould contamination was between 10-15m2. Inspection of the kitchen areas identified a significant extent of mould contamination to plasterboard wall panelling behind kitchen units and inside of the kitchen cavity wall. The relative moisture content of the wall plasterboard is normal indicating historic contamination currently in dormant state. This area is directly connected to with the bathroom areas via opening in the plasterboard partition wall. This area is also a significant source of damp and mould related odours in the property.

mould under bath

I have collected a number of air samples from the property to evaluate the level of indoor air contamination by mould spores. My assessment showed there was marginally lower concentration of mould spores in the indoor environment in comparison to the external background sample. The indoor air samples were however dominated by Aspergillus/Penicillium genera and also mould genera such as Stachybotrys and Chaetomium frequently associated with water damage were also identified indoors in relatively small concentrations.

fungal rot under bath

The surface samples collected from the visible mould contamination on various surfaces within the property show presence of mainly water damage moulds such as Stachybotrys and Chaetomium.

mould on plasterboard

mould in wall cavity

In my assessment I have concluded that the most likely reason for odours in the property is continuous fungal rot of the bathroom timber flooring and large extent of fungus contaminated plasterboard panelling in both the bathroom and the kitchen. The indoor air is not significantly contaminated by fungal spores, however water damage (Chaetomium) and toxic (Stachybotrys) fungal genera have been detected indoors. I have strongly recommended to remove the water damaged and rotten timber flooring and remove existing fungal contamination to the walls of the kitchen and bathroom. The removal of the contaminated materials should be carried out under controlled conditions.

By Tomas Gabor

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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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