In January I was invited once again to the north of the country to investigate long lasting and persistent indoor air quality and odour problem in newly build country house. The building was about two years old and very early after moving into the property one of the downstairs bedroom was suffering from persistent poor indoor air quality and odours.
The smell appeared to be concentrated in the adjacent bathroom. Several contractors have visited the site including the builders and the bathroom suppliers trying to identify the problem. Unfortunately the only thing they could all agree on was that the smell is odd but nobody could find the fault. The building pipe work has been inspected by a specified contractor who could not identify anything wrong.
I was initially called in to investigate possible mould contamination problem but soon after the visiting the site I knew that mould are unlikely cause of the poor indoor air quality. We have changed the scope of the investigation from contaminant sampling and identification to fault finding.
Thorough inspection of the bathroom did not reveal any moisture related problems, the room and all adjacent rooms were damp free, internal humidity was in normal levels, floors were sound and undamaged and extraction pipe work clean and without stagnant water. At this point I had to get a bit more creative to pinpoint the fault. It was obvious to me that the problem lies with the sewage drain system. So I have decided to pump strongly smelling and very characteristic non hazardous chemical into the drain system under very low pressure and observe the presence of this chemical indoors. As it turned out shortly after begging of the exercise we could smell the odour firstly in the downstairs bathroom and a bit later on in the upstairs bathroom.
The source of the odour could not be linked to any of the utilities so it became obvious that there has to be damaged or opened sewer pipe somewhere in the cavity walls.
I have made several small access points in the cavity wall to insert my camera and inspect the pipe work. I have discovered wrongly connected sewage pipe at the ceiling level of the bathroom.
Leaking sewage pipe at ceiling level
The pipe was draining small amounts (app. 200ml with every flush) of faeces contaminated water into the downstairs wall cavity saturating the mineral wool insulation. The whole cavity was contaminated by film of bacteria some of them harmful. These bacteria and the sewage water were releasing the unpleasant odours.
- Sewage saturated insulation in cavity wall
The result of my investigation the downstairs bathroom wall had to be taken down, leaking pipe work repaired by a contractor and whole bathroom decontaminated.
By Tomas Gabor
