Module 5 · Biological Agents
5.3 Dry Rot: The Reputation and the Evidence
9 min read
No organism in British building pathology carries more freight than dry rot. It has been used to justify wholesale timber replacement, extensive masonry irrigation and the removal of historic fabric that a proportionate response would have kept. The reputation is not baseless — Serpula does have capabilities other decay fungi lack — but the gap between what it can do and what it is routinely said to do is where a great deal of unnecessary work has been sold.
Learning objectives
By the end of this lesson you will be able to:
- State what Serpula genuinely does that other decay fungi do not.
- Identify the claims about it that the evidence does not support.
- Specify a proportionate response and justify each element of it.
- Advise a client where a specialist's recommendation appears disproportionate.
Key terms
- Environmental control
- Remediating decay by removing the moisture and ventilating, rather than by chemical application. The primary approach in current conservation practice.
- Irrigation
- Injecting fungicide into masonry to sterilise it. Historically routine in dry rot treatment and now regarded as rarely justified.
- Dormancy
- The fungus surviving inactive in dry conditions. Real, but far more limited in duration than the traditional claims suggest.
- Proportionate response
- Treatment scaled to the established extent and the actual risk, with each element justified by what it addresses.
Read the rest of Biological Agents
Module 1 is open to everyone. The remaining six modules — building science, each damp mechanism in depth, meters and thermal imaging, the full inspection method, and report writing — are free too. We just ask for an email so you can pick up where you left off, and so we can send your certificate when you finish.