Condensation and Mould Survey
Condensation is the most common cause of damp and mould in UK housing — and the most commonly misdiagnosed. Black mould on a bedroom wall gets blamed on rising damp, leaks, or 'tenant lifestyle', when the real cause is usually a measurable imbalance between moisture production, heating, insulation, and ventilation. Our condensation and mould survey measures that balance and identifies exactly what needs to change.
The stakes have risen sharply for landlords. Under Awaab's Law, damp and mould hazards in rented homes must be investigated and addressed within strict timescales, and 'lifestyle' is no longer an acceptable answer without evidence. Our survey provides the professional investigation the law requires — with objective humidity data, ventilation assessment, and a clear remedial pathway.
For homeowners, the survey answers the practical questions: why does mould keep returning after cleaning, why is one room always worse, and what combination of ventilation, heating, and insulation improvements will actually fix it — rather than the scattergun of gadgets and repainting that usually precedes a proper diagnosis.
What the Condensation and Mould Survey Covers
- Room-by-room relative humidity, temperature, and dew point measurement
- Surface temperature profiling to locate cold spots and thermal bridges
- Ventilation assessment: extractor performance, trickle vents, airflow paths, and habits of use
- Moisture production review: bathing, cooking, drying laundry, occupancy density
- Mould distribution mapping and severity assessment
- Elimination check for other damp sources masquerading as condensation (leaks, penetrating damp)
Signs You Need This Survey
- Black spot mould on walls, ceilings, or around windows
- Streaming windows on cold mornings
- Mould growing behind furniture or inside wardrobes
- Musty smell in bedrooms or poorly ventilated rooms
- Mould returning quickly after cleaning
- Tenant complaints of damp, mould, or condensation
Who This Survey Is For
Landlords and letting agents responding to tenant damp and mould reports — where an independent professional investigation is now effectively a legal requirement under Awaab's Law; homeowners fighting recurring mould; and buyers of flats where condensation staining raises questions. The survey provides objective measurements, which is precisely what separates a defensible response from an assumption about lifestyle.
Our Survey Process
1. Occupancy and symptom history
We establish how the home is used — occupancy, bathing and cooking patterns, laundry drying, heating regime — and the history of the mould problem, because condensation is always a systems problem involving building and use together.
2. Environmental measurement
Relative humidity, air temperature, and surface temperatures are measured room by room to calculate dew point margins — identifying exactly where and why moisture is condensing.
3. Ventilation performance testing
Extractor fans are checked for actual performance (not just presence), background ventilation is assessed, and airflow paths through the home are traced. Underperforming extraction is the single most common finding in London mould cases.
4. Fabric and cold-spot analysis
Thermal bridging, uninsulated elements, and cold corners are identified — the fixed points where mould concentrates regardless of behaviour. This is what distinguishes building-fault condensation from use-related condensation, the distinction Awaab's Law cases turn on.
5. Remedial pathway and compliance report
You receive a report with the measured evidence, a clear diagnosis of the moisture balance failure, and a prioritised remedial pathway across ventilation, heating, insulation, and use — written to satisfy compliance scrutiny where required.
What You Receive
- Objective humidity, temperature, and dew point data per room
- Ventilation performance findings with specific upgrade recommendations
- Mould severity and health-risk contextualisation
- Clear apportionment: building factors vs use factors, with evidence
- A prioritised, realistic remedial plan (typically ventilation first)
- Awaab's Law compliant documentation for landlord records
Why Choose Henderson Wood?
- Evidence-based diagnosis instead of lifestyle assumptions
- Purpose-built for Awaab's Law investigation requirements
- Identifies the cheapest effective fix — often extraction, not building works
- Objective data protects landlords and tenants alike
- Stops the repaint-and-return mould cycle for homeowners
- Experienced with London's condensation-prone flats and conversions
Frequently Asked Questions
What does Awaab's Law require landlords to do about mould?
Awaab's Law sets fixed timescales for social landlords (with the principles extending across the rental sector) to investigate reported damp and mould hazards and to begin remedial work. The investigation must be meaningful — a professional survey with measurements and a written report is the clearest way to evidence compliance, and 'tenant lifestyle' without supporting data is not a defensible conclusion.
Is mould dangerous to health?
Mould exposure is associated with respiratory conditions, allergies, and asthma aggravation, with children, older people, and those with existing respiratory conditions most at risk. Severity depends on extent, species, and exposure — our survey assesses the scale of the problem and prioritises remediation accordingly. Significant mould in sleeping areas should always be treated as urgent.
Is it condensation or rising damp?
They present differently and we measure the difference: rising damp shows a characteristic moisture profile rising from floor level with salts; condensation concentrates on cold surfaces, corners, and behind furniture with high measured humidity. Getting this wrong wastes serious money — chemical damp courses are regularly injected into walls whose only problem is a broken extractor fan.
Can't the tenant just open the windows more?
Ventilation habits matter, but modern airtight refurbishments, absent or underpowered extraction, cold bridging, and high occupancy are building factors the tenant cannot fix. Our survey measures both sides and apportions cause with evidence — which protects everyone, including landlords from claims and tenants from blame.
What fixes actually work for condensation mould?
In order of typical effectiveness per pound spent: working continuous or humidity-triggered extraction in kitchens and bathrooms, ensuring background airflow, addressing dominant cold bridges, and adjusting heating patterns. Whole-house solutions like PIV units help in the right cases. Our report specifies which of these your property actually needs, and in what order.
How much does a condensation and mould survey cost?
Pricing depends on property size — contact us for a fixed quote. For landlords, it is a small cost against the compliance, void, and claims risks of an undocumented mould complaint.
When to Book
- • A tenant has reported damp or mould (Awaab's Law clock is running)
- • Mould keeps returning after cleaning and repainting
- • Windows stream with condensation every winter
- • Mould is appearing behind furniture or in wardrobes
- • Before installing ventilation upgrades, to specify them correctly