Module 3 · Types of Damp in Detail
3.7 Mixed Damp Problems
7 min read
The tidy single-mechanism case is a teaching device. On site you will regularly find a cold wall with a bridged DPC and a slow leak behind it, and the client's experience of having "had it fixed twice already" usually means someone found one cause and stopped. This lesson is about handling multiplicity without losing rigour.
Learning objectives
By the end of this lesson you will be able to:
- Recognise when more than one mechanism is contributing.
- Rank causes as primary, secondary and contributory.
- Explain how one mechanism can mask or mimic another.
- Structure a finding that addresses several causes without hedging into uselessness.
Key terms
- Primary cause
- The mechanism responsible for most of the moisture, whose removal produces most of the improvement.
- Secondary cause
- A genuine additional source or retention condition contributing materially but not dominant.
- Contributory factor
- Something that does not introduce moisture but makes the problem worse — poor ventilation, blocked airflow, a sealed finish.
- Masking
- One mechanism producing symptoms that conceal or imitate another, so the second is never found.
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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.