In early October of 2016, our All Dry offices received an inquiry via the contact us form on our website alldrydampproofing.com from a man who told us he thought that his property may have an outbreak of Dry Rot (Serpula lacrymans) on the front porch of their house. He also said there was a damp musty smell in the basement sauna and they have noticed a red dust on the tiled floor.
We sent our surveyor to investigate and carry out the initial survey and identification. There was obvious decay to the timbers of the front porch with the bottom panel and legs of the porch disintegrated The timbers were a dark colour and had cuboidal cracking. Where the timbers were missing a silky grey colored skin was visible, this is called the mycelium. Running into the brickwork strands could be seen and these were a thick walled hyphae.
Next, we needed to identify the source of moisture, the Dry Rot spores need a lot of moisture to germinate, timbers need to have a 28-30% moisture content and this would be similar to timber that is in contact with damp masonry. We consider 22% moisture content in existing timbers the starting point for decay. The source of moisture was the damp timber but also water was running down the wall floor angle externally. We were told that there was an old coal chute to the left elevation, and where the sauna was this was the old coal place. We now had worked out this was the source of moisture.
Inside the property and below the porch a basement conversion had been carried out some 10 years previous, and this was done to a high standard. Exactly below the porch was a toilet and sauna. Around the access panel to the macerator for the toilet, a red dust had been appearing on the tiles as well as the musty damp smell.
With the basement conversion and sauna in place, the survey was limited but we had identified and confirmed there was an outbreak of Dry Rot.
The Next Step
After liaising with the client and diagnosing dry rot we then had to find the extent of the problem. To do this would require a paid survey and invasive testing. The customer agreed to the paid survey and a date was set, test holes were cut out of the render in the porch and drill holes in the pointing looking for any further strands. the plaster lath ceiling of the porch was opened up in the search and results noted. what we were searching for was a fruiting body (sporophore) and these usually look like something off Dr. Who. (see below)
After the survey was finished around the porch area we moved into the basement. We knew there must be a fruiting body somewhere because of the red rust coloured spores in the form of dust around the macerator access. After the test holes were cut in the plasterboards there was only one tool that we could use to find the fruiting body, and that was the boroscope. it was extremely difficult to find the fruiting body as we had to point it every direction. We eventually found the fruiting body in the wall ceiling angle and there was a white cotton wool like mycelium running all the way along the angle of the concrete ceiling slab.
Expensive Remedial works
After finding the fruiting body our surveyor could then go back to the office and type up a report on his findings. Even though the fruiting body had been found the survey was still limited with the sauna, appliances and Type C waterproofing all still in place. The customer also did not want any plaster disturbing in the hallway above the sauna or in the room adjacent where items were stored.
Our customer agreed to use his own contractors to remove the fitting and sauna so a full diagnosis or costs could not be done while they were in place. It was however agreed that our report and quote on the outside remedial works should go ahead. This was to eradicate the source of moisture and all contaminated timbers, as well as treating the brickwork and any timbers left in place.
The program of works was to:-
Take away the old porch timbers, install an Aco drain at the wall floor angle, hack off render inside the porch, grind brickwork to 10-15mm treat masonry and re-point, re-render the inside of the porch, treat masonry with StormDry Masonry Protection Cream.
We were waiting quite a while for the fittings to be removed from inside the sauna but eventually, we were able to get in and survey the room. We had to cut back the existing Type C membrane to see the extent of the dry rot and the system the previous contractors had used when converting the basement.
The system did not comply with BS 8102 so it was discussed with our customer and decided to reinstate the membrane back as it was after we had made clear what could happen if water came to bear on the structure. The alternative was to redo the whole basement which was just not feasible.
The system of repair was to remove all decayed timber and debris, grind and point masonry to a depth of 10-15mm up to 600mm from last evidence of fungal decay, treat masonry and existing timbers with a biocide containing zinc oxychloride, render the wall with sand and cement at 6-1 to reduce any ingress, reinstate cavity drainage membrane and seal with rubber butadiene tape, reinstate fittings.
Our works were finally finished last month with the customer’s own contractors reinstating the rest of the fittings. We have had to work with the customer who was away working in the UAE for the length of the contract. With the locality of the fungus and the fact the customer did not want other areas of the property disturbed the works were limited and all consequences fully explained. We guaranteed the works we carried out and the customer was extremely happy with how professional we were in working with him. We sent photos of the works as we went along and kept him updated at all times.
If you suspect you have the Dry Rot Fungus and would like a survey please use our contact us via our website alldrydampproofing.com if you visit the site we will give you a Free E-Book on identifying the different types of damp in your property just for being interested.
If you click the menu bar in the top right on the web page you can also access the basement conversion page and if you scroll down to the bottom we will give you another Free E-Book on Things You Should Know about Basement Conversions.
We hope you have found this case study helpful in some way and will one day become one of our valued customers.