Client: Domestic
Our client, a homeowner in London, tasked Timberwise with surveying the property for problems associated with dry rot fungal decay. This property was a semi-detached house of solid brick construction, and was both occupied and furnished at the time of our inspection. It was a semi-detached property that was constructed in 1885. The weather conditions were overcast but dry.
Challenges
This project proved to be an extensive task for Timberwise. Our survey revealed an active dry rot outbreak that had spread across three floor levels, including the ground, first, and second floors. The property was 140 years old, with construction finishing circa 1885. This meant that great care had to be taken while dealing with the outbreak.
Our inspection of the timbers was restricted to accessible exposed surfaces as the property was occupied and furnished at the time of inspection and subsequent remediation. We also discovered decayed timber lintels above the first-floor windows which required structural replacement due to the safety threat they posed. It was also paramount for our team to coordinate remediation carefully to ensure the building remained watertight to prevent further infection to the property and adjoining ones.
Observations
We conducted a brief external inspection of the property from the ground level only during our visit. We noted defects with the guttering, pointing, and facing masonry of the property. For the guttering, we noted damp staining on the brickwork of the front elevation.
This was likely due to defective rainwater goods, particularly a blocked hopper. Our team had been informed that it had been a persistent problem for a number of years and only recently had been rectified. There were isolated patches of defective mortar pointing on the front elevation which was likely to cause damp penetration. Facing bricks were spalled to the front elevation, which was also likely to cause damp penetration.
Our survey found an extensive and concerning dry rot fungal decay (Serpula lacrymans) outbreak that had infected the front right rooms of the ground, first, and second floors of the property. We found fungal hyphae, mycelia, and conducting strands which indicated a potential colonisation of the masonry mortar layers. The moisture sources for the fungal attack were attributed to the aforementioned leaking gutters, porous masonry, and defective pointing.
Solutions
Our team devised a plan to remediate the issue. The area had to be prepped and cleaned, with the dry rot removed and the masonry cleaned. Timber would also need to be replaced in certain areas. We began by protecting work areas using dust sheets and hardboards where necessary. We applied polythene sheeting over free-standing personal items to prevent dust settling on them. We would remove and dispose of all resulting waste and debris from the property to prevent any contamination from the dry rot.
It was critical that the team contained the outbreak and prevented it from recurring. We proposed and installed a toxic box (cordon sanitaire) to all affected wall areas. Our team drilled 12mm to 16mm diameter holes at 450mm staggered centres in a 300mm wide band around the periphery of the affected walls. We then applied a LignaTek Fungicidal treatment to the masonry holes and wall surfaces. It will act as a chemical and structural barrier to prevent the spread and penetration of dry rot into the timber and masonry of the property.
There was also significant timber repair to be done due to the extensive damage the dry rot had caused to certain areas.
Our team cut back six ceiling joists to sound timber and fitted new pre-treated rafters via splicing or bolted repairs. We removed and replaced the decaying ceiling joists using pre-treated timber. We also used pre-treated timber to repair two linear metres of wall plate. Timber lintels above the first-floor window were replaced with a new pre-stressed concrete lintel. Our team also installed new pre-treated floor joists and moisture-resistant chipboard flooring to prevent any water damage from subsequent leaks. Any timber ends in contact with masonry were isolated from said masonry through the use of a damp proof membrane (DPM) or a damp proof course (DPC), depending on where suitable. All of the timber ends that were used were treated with a fungicidal coating prior to installation as well, which would help to contain and prevent any spores.
The project was finished off by the application of a DryTek salt retardant re-plastering specification to all of the affected walls, to further prevent moisture ingress and any resulting problems. A structural replacement of the ceiling on the first floor was also undertaken.
Results
Our team successfully eradicated and contained an active dry rot outbreak through the use of a targeted fungicidal treatment, a toxic box method, and structural timber replacement. We were able to restore the structural integrity of the floors, ceilings, and window openings. A specialist plastering system and toxic box we installed will mitigate any future moisture and salt migration, providing a long-term guarantee for the client.
Do You Want Help with a Dry Rot Solution?
Our dedicated and experienced team in North London are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 020 8226 6486, or you can request a survey online.
