Mould Severity Checker
Six questions — extent, recurrence, concealment, occupants — scored into a severity rating with the proportionate response, from safe self-cleaning to urgent professional action.
How serious is my mould problem? Severity scales with extent, persistence and who's exposed. Small surface patches (under ~1m²) in a non-vulnerable household are safely self-cleaned while the cause is fixed; larger, recurring or concealed growth warrants professional remediation (£200–£600/room); and significant mould around babies, older people or anyone with respiratory or immune conditions moves the timescale to 'now'. This checker scores your situation against those thresholds — grounded in NHS guidance on mould health risks — and returns a rating with the matching action. Landlords: a 'High' or 'Urgent' result in a rental is a compliance clock already running.
Use the diagnostic
Answer the questions
Answer honestly — the rating is only as good as the inputs. Nothing is stored or sent.
1. How much visible mould is there in total?
2. Does it come back after cleaning?
3. Any signs of concealed growth?
4. Who lives in the affected home?
5. Are health symptoms tracking the home?
6. Is the property rented out?
Related services and guides
Black Mould Removal
The service this tool points toward — diagnosis-first, independent qualified providers.
View the serviceMould Surveys
The service this tool points toward — diagnosis-first, independent qualified providers.
View the serviceDamp and Mould: Health Risks and What to Do
The in-depth guide behind this tool's logic.
Read the guideThe Complete Guide to Condensation and Mould
The in-depth guide behind this tool's logic.
Read the guideMould Severity Checker FAQs
No — it's a proportionality tool grounded in NHS housing-and-health guidance. Health symptoms belong with a GP; this checker helps scale the building response and flags when speed matters.
Babies and young children, people over 65, and anyone with asthma, COPD, other respiratory conditions, allergies to mould, or weakened immunity (illness or medication). Their presence legitimately moves the urgency, per the health evidence.
Containment of the affected area, HEPA-filtered removal, treatment of surfaces, verification — £200–£600 per room in North London — always paired with the moisture-cause fix, or the growth returns on schedule.
Start the documented sequence today: written acknowledgement to the tenant, independent investigation within days, cause-led remediation promptly, everything dated and filed. The landlord compliance guide and checklist walk it step by step.
Want a professional answer, not just an estimate?
Call today or book a survey — the right independent qualified specialist, matched to your property.