Large-Scale Dry Rot Discovered in a North London Property - A Real Case Study

The house had sat empty for many years, and as soon as it was bought, squatters moved in and refused to leave. By the time they eventually vacated, the property had been left in a poor condition. On top of the visible damage caused by neglect, there was a hidden problem no one had noticed: a plumbing leak on the first floor.

How the problem developed

The leak had been ongoing for some time while the squatters were in residence. Water had tracked down into the study area below and penetrated the timber suspended floor. Out of sight, in the sub-floor void, conditions had become perfect for dry rot to develop – and by the time we surveyed, the outbreak was already on a very large scale.

What we found during the survey

  • Extensive dry rot fruiting bodies and heavy mycelium growth spreading throughout the sub-floor.

  • Moisture detected in the adjacent wall plaster, confirming that the rot was likely travelling through the masonry walls.

  • Long-term contamination of timbers, making them structurally unsound.

 

Understanding dry rot

Dry rot is one of the most serious timber decay problems a property can suffer. Caused by the fungus Serpula lacrymans, it thrives in damp, poorly ventilated areas where moisture levels are raised. The fungus can:

  • Spread rapidly through timber, masonry and plaster.

  • Produce fruiting bodies that release spores, leading to further outbreaks.

  • Cause significant structural damage if left untreated.

What makes dry rot particularly destructive is its ability to travel through masonry walls in search of new timber to feed on, making it more invasive than most other forms of decay.

 

Our recommendations to the client

Breaking the news to the new owner was not easy – the extent of the outbreak was severe. However, by following correct industry procedures, the issue could be contained and resolved. Our recommendations included:

  • Cutting back and replacing all contaminated timbers within the affected areas.

  • Hacking off wall plaster up to 1 metre beyond the visible contamination and replastering with appropriate materials.

  • Treating all affected areas with a fungicidal solution to kill off residual spores and prevent re-growth.

  • Addressing the source of moisture by repairing the plumbing leak and improving ventilation to reduce future risk.

Conclusion

Explaining the scale of the damage to the property investor was unpleasant but essential. Without identifying and properly treating the dry rot, the structural integrity of the property would have continued to decline.

At ProCheck Damp & Timber, we pride ourselves on uncovering the full extent of damp and timber problems, no matter how hidden they may be. Our role is to provide accurate diagnosis and clear recommendations first — and, where works are required, to ensure they’re carried out effectively. This approach gives property owners the confidence to make informed decisions and protect their investments for the long term.