Quick answer: Compliant mould remediation under Awaab Law and COSHH 2002 requires H-Class vacuum extraction, a documented method, COSHH-compliant chemical selection, and evidence of completion that the landlord can use for their compliance record. Surface treatment without H-Class extraction simply redistributes mould spores into the property air. Chemical treatment without first addressing the ventilation cause of mould will result in recurrence. This step-by-step guide covers the correct process from site assessment through to completion documentation.
Mould remediation in social housing, private rented sector and care home properties is now a regulated activity in everything but name. Under Awaab Law, landlords must investigate within 14 days and complete emergency remediation within 7 days. Under COSHH 2002, mould spores are biological agents requiring controlled exposure. Under the HHSRS 2026 overhaul, biocides used incorrectly in remediation are themselves a scoreable Indoor Air Pollutants hazard. Getting this wrong has consequences for the landlord, the contractor and the occupants.
Before you start -- site assessment
Before beginning any mould remediation, assess the following:
- Extent of contamination -- is this surface mould on paintwork, or has it penetrated substrate? Plasterboard, insulation and timber with deep mould penetration may require removal rather than treatment.
- Cause of mould -- surface mould without addressing the underlying cause will return. Identify whether the cause is condensation (ventilation failure, lifestyle factors, heating failure), penetrating damp (roof, guttering, DPC failure) or rising damp. Remediation without cause identification is not a complete job.
- Pre-2000 building -- asbestos risk -- textured coatings (Artex), floor tiles, ceiling tiles and some plasters in pre-2000 buildings may contain asbestos. Do not disturb these surfaces without an asbestos survey. H-Class extraction is mandatory for any vacuum work near suspected ACMs. See: Control of Asbestos Regulations 2012
- Ventilation in the property -- check extract fans in bathroom and kitchen are working. Check trickle vents in windows are open and unblocked. A mould remediation job that does not include a ventilation check is incomplete.
Step 1 -- Contain the area and protect occupants
Where mould contamination is significant, contain the work area before starting. This means:
- Removing soft furnishings, clothing and personal items from the immediate area
- Ensuring occupants -- especially vulnerable residents, children, elderly, immunocompromised -- are not present in the property during remediation
- Sealing HVAC vents in the work area to prevent spore redistribution through the ventilation system
- Operative PPE -- FFP3 respirator (face-fit tested), disposable coverall, gloves and eye protection
Step 2 -- H-Class vacuum extraction before any chemical application
This is the step most contractors skip -- and it is the most important one.
Before applying any chemical treatment, H-Class vacuum extraction of visible mould growth removes the bulk of surface contamination and captures spores before they become airborne. Applying a biocidal spray to surface mould without first vacuuming it disturbs the mould and releases spores into the air. H-Class vacuum first, treatment second.
H-Class -- not M-Class. Mould spores are biological agents under COSHH. M-Class vacuums are not rated for biological agents. H14 HEPA filtration at 99.995% with sealed Type H disposal bags is the correct specification. See: H-Class extraction
Step 3 -- Consider mechanical removal before chemical application
Under the COSHH hierarchy of control, employers must consider whether the hazardous substance (the biocide) can be eliminated or substituted before introducing it. Where mould can be removed mechanically -- by H-Class vacuum and physical removal of affected substrate -- this should be considered before applying a biocidal chemical in an occupied property.
For surface mould on hard, non-porous surfaces, mechanical removal by H-Class vacuum followed by physical wiping of the surface (operatives wearing PPE) may be sufficient without chemical application. For porous surfaces with established mould penetration, biocidal treatment is likely necessary -- but it comes after mechanical preparation, not instead of it.
Step 4 -- Biocidal treatment where required
Where biocidal treatment is required, the product must:
- Have a current Safety Data Sheet -- updated to reflect August 2026 GB CLP classifications if after that date
- Not be marketed as non-toxic, harmless or safe -- these claims are non-compliant under BPR. See: Biocide labelling compliance
- Be applied in accordance with the SDS -- correct dilution, correct dwell time, adequate ventilation during and after application
- Be covered by a COSHH assessment specific to this product and this job
Step 5 -- Address the cause
Before leaving the job, document the identified cause of mould and -- where within the scope of the contract -- address it. At minimum, the landlord should receive a written note of what was found, what was done, and what further works are required to prevent recurrence. This protects the contractor from being called back when mould returns due to a cause that was identified but not addressed.
Step 6 -- Completion documentation
The landlord needs a completion record for their Awaab Law compliance file. This should include:
- Date and time of attendance
- Extent of mould found and areas treated
- Method used -- H-Class extraction, physical removal, biocidal treatment (product name and SDS reference)
- Equipment used -- make, model and classification of extraction equipment
- Identified cause and ventilation assessment findings
- Any further works recommended
- Operative name and signature
View V-TUF H-Class dust extractors | Awaab Law guidance | H-Class extraction
Related guidance
Awaab Law | COSHH Regulations 2002 | H-Class extraction | Social housing hub | Biocide labelling compliance | HHSRS 2026 overhaul
