As building surveyors, we encounter issues with dampness, mould, and condensation on a daily basis. But how often do we pause to think about what's causing it, what’s changed in recent legislation, and just how much our advice matters?
The days of brushing off a bit of mould as "just condensation" are gone. With new legislation, including the Building Safety Act, and in the wake of the Grenfell tragedy, we're in a new world. As professionals, we carry more responsibility than ever, ethically and legally. It's time to shake off that "wild west" image of the mould and damp industry.
Imagine a four-bedroom house once occupied by a retired couple — barely any cooking, minimal washing, windows often open, and the heating ticking along gently. Life was calm, and moisture levels stayed low.
Now picture the exact same house, but now it’s home to two parents and four teenagers. Showers twice a day, kettles steaming, pans bubbling, laundry drying indoors, bedroom doors shut tight, and curtains drawn like they’re shielding against garlic and sunlight. Welcome to Teen Dracula’s lair.
The bricks haven’t changed, but the internal environment has.
But here’s the thing: We can no longer blame lifestyle alone. Not since Awaab’s tragic death brought national attention to the issue of mould and health. If a property can’t cope with everyday day-to-day life — with children, cooking, bathing, and drying clothes — then it’s the property that’s failing, not the people.
Landlords, housing providers, and yes, even we as surveyors, need to shift the mindset. Condensation mould is rarely just about careless living — more often, it’s about poor design, insufficient ventilation, or inadequate heating provision.
We routinely carry damp meters. But how many of us carry humidity meters? If you're called back months later to a property now filled with mould, your damp readings on the day may not be enough to defend your position. Humidity data could be your best ally — and your professional protection.
Energy efficiency has created an irony. The more airtight we make buildings — with double glazing, insulation, and draught-proofing — the less the home can breathe. Moisture gets trapped, and unless there's decent mechanical ventilation (that people actually use), you've got a recipe for trouble.
How often do we find trickle vents sealed, or mechanical ventilation switched off because it's "too noisy at night"? This highlights the need for an integrated building design approach that prioritises both energy efficiency and robust, controlled ventilation systems.
According to Dr. Aaran Marriner-Clark — a certified mould remediation expert and mycology researcher — black pin mould (Stachybotrys chartarum) doesn't just grow when things get a little damp. This species is classified as "one of the world's 10 most hazardous fungi", primarily due to its mycotoxins, which can induce "necrotic changes and even life-threatening pulmonary or gastrointestinal haemorrhage". It's particularly toxic to the rapidly developing lungs of infants.
Stachybotrys chartarum requires significant moisture for active growth, typically requiring a water activity greater than 0.9 (aw > 0.9) and a relative humidity exceeding 90% (RH > 90%). It thrives by breaking down cellulose-rich materials like paper, wood, drywall, gypsum, calcium, and paint.
Even more alarming? Dr. Marriner-Clark's research shows that the mould's colonisation is a "reaction to the availability of magnesium and calcium in the paint and the gypsum", and that "sodium in the gypsum plasterwork is a limiting factor for Stachybotrys Chartarum growth". Prolonged water saturation can leach sodium out, reducing its inhibitory effect and allowing this species to flourish due to the remaining high levels of calcium. It’s not just moisture — it’s chemistry. Our plasterwork is sometimes laying out the red carpet.
Crucially, incomplete mould removal can make the remaining mould up to 90.9% more toxic. A failed attempt at remediation can inadvertently exacerbate the hazard. That's not just bad science — that’s potential liability.
Despite Stachybotrys chartarum posing a significant risk and having a "proven track record of fatality" , it's astonishing that "there are not currently any Environmental Protection Agency (EPA) regulations or guidelines for evaluating potential health risks of S. chartarum contamination and remediation, in the US or UK!". It "is not treated in the same way AS Asbestos Lead" , and there is "no definitive guidance on eradication methods for Stachybotrys Chartarum in dwellings in the UK by Government or Industry Standards". This regulatory vacuum leaves professionals navigating what’s increasingly seen as a ‘wild west’ — one with serious consequences for health, liability, and litigation.
However, existing legal frameworks provide crucial avenues for recourse. Under British case law, the landmark precedent set in
Summers v Salford Corporation 1946 established that any black pin mould within a property is considered "prejudicial to health". This means a property with black mould can be deemed "unfit for human habitation under The Fitness for Human Habitation Act 2018" and "prejudicial to health under Environmental Protection Act 1990 section 79 (1)a". Additionally, mould constitutes a "Hazard under the Housing Act 2004".
Recent cases such as
Jillian's v Red Kite Community Housing (2024) further reinforce the application of the 'fitness for habitation' test, linking it to Section 9A of the Landlords and Tenants Act. This shows that courts are leaning more heavily on the “fitness for habitation” argument, and it includes condensation-related mould, not just leaks or structural defects.
Here’s the modern toolkit every surveyor should carry into a potentially damp environment:
And above all, document your advice clearly. Even if nothing’s visible on the day, your report may become your only alibi six months later.
The independent review led by Dame Judith Hackitt, initiated in the wake of the Grenfell Tower fire, makes clear that competence, accountability, and a proactive approach to building safety are no longer optional. Her findings underscored the urgent need for a fundamental "cultural shift". While her recommendations primarily focus on fire safety in High-Risk Residential Buildings (HRRBs), the principles — like clear "duty holders" , a "golden thread" of information, and raising competence levels — apply just as urgently and robustly to mould and internal environmental quality.
We simply cannot afford to treat mould as a cosmetic issue. It's a critical building safety issue — and we, as surveyors, are on the front line. Professional bodies like the Residential Property Surveyors Association (RPSA), the Institute of Specialist Surveyors and Engineers (ISSE), and the National Institution of Black Mould Experts (NIBME) are actively engaged in initiatives to professionalise the industry, looking to actively change this within the industry by pursuing "Regulation, Ethics, Higher standards, Method Statements, Education, Lobbying for change". This aligns perfectly with Hackitt's vision for a proactive safety culture.
Let’s keep our eyes open, our meters ready, and our advice clear. And let’s help ensure that no teenage bedroom ends up a biological hazard — or a court case waiting to happen.
