4 Stage Clearance Certification
Four stage clearance is the formal process that confirms, through four sequential stages, that an asbestos removal enclosure may be dismantled (after Stage 3) and that the area is fit for reoccupation (after Stage 4). Our BOHS P403/P404 qualified analysts provide independent clearance certification, ensuring compliance and protecting building occupants.
What Is 4 Stage Clearance?
Four stage clearance is the clearance procedure carried out after licensed asbestos work in an enclosure. It involves a structured sequence of visual inspections and air testing by an independent analyst not employed by the removal contractor. Passing Stage 3 allows the enclosure to be dismantled; once Stage 4 is also passed, a Certificate for Reoccupation is issued, confirming the area is fit for reoccupation.
When Is 4 Stage Clearance Required?
- After completion of licensed asbestos removal works
- Before dismantling any asbestos removal enclosure
- Before returning any removal area to normal occupation
- When formal certification is required for compliance records
- For handover documentation on construction projects
- Where duty holders require independent verification of removal completion
Who Needs 4 Stage Clearance?
- Licensed asbestos removal contractors completing enclosure works
- Building owners and duty holders overseeing removal projects
- Project managers requiring handover documentation
- Principal contractors managing site safety compliance
- Facilities managers arranging building reoccupation
- Healthcare and education premises requiring formal clearance records
What You Receive
- Formal Certificate for Reoccupation for each cleared area
- Stage-by-stage inspection records and photographs
- Air test results with laboratory analysis certificates
- Analyst site attendance notes and observations
- Complete certificate pack for compliance records
- Electronic and hard copy documentation as required
The Four Stages Explained
Stage 1: Preliminary Check
A preliminary check of site condition and job completeness. The plan of work and the contractor's handover document are checked, and the enclosure's integrity, the decontamination unit, the areas around the enclosure and the transit and waste routes are inspected. Waste should already have been removed from the enclosure.
Stage 2: Thorough Visual Inspection
Detailed inspection after initial clean. The enclosure must be free of all visible debris, dust, and residue. All surfaces must be visually clean before air testing can commence.
Stage 3: Air Monitoring
Clearance air sampling inside the enclosure while surfaces are disturbed by brushing and sweeping. Samples are analysed by phase contrast microscopy (PCM), and every result must be below the clearance indicator of 0.010 f/ml. Passing Stage 3 allows the enclosure to be dismantled; on its own it is not clearance for reoccupation.
Stage 4: Final Assessment
After the enclosure has been dismantled, a final visual assessment of the former work area and the waste and transit routes checks for any debris released or uncovered during dismantling. The Certificate for Reoccupation is issued only when all four stages have been passed.
Frequently Asked Questions
Why must clearance be conducted by an independent analyst?
Independence ensures objectivity. The analyst must not be employed by the removal contractor to avoid conflicts of interest. Independent certification provides assurance to duty holders that the clearance process has been conducted impartially.
What is the clearance fibre level for reoccupation?
The clearance indicator is an airborne fibre concentration below 0.010 fibres per millilitre (f/ml), measured by phase contrast microscopy (PCM) with surfaces inside the enclosure disturbed during sampling. This air test is Stage 3. Achieving it allows the enclosure to be dismantled, but it is not the end of the process: the Stage 4 final visual assessment is carried out after dismantling, and the Certificate for Reoccupation is issued only when all four stages have been passed.
What happens if clearance testing fails?
If clearance requirements are not met, a Certificate for Reoccupation cannot be issued. The analyst records the problem and the removal contractor carries out the necessary remedial work, including further cleaning where needed. After a formal Stage 2 failure, the process restarts at Stage 1 once the contractor’s supervisor has reinspected the enclosure and issued a new handover document. Problems at other stages are addressed using the relevant HSG248 procedure. All four stages must be satisfactorily completed before reoccupation.
How long does the 4 stage clearance process take?
The time needed depends on the size and layout of the enclosure, the condition of the site, how long the visual inspections take and the air-sampling requirements for that enclosure. We provide a project-specific estimate when booking. Same-day clearance may be possible, depending on the size and condition of the enclosure and successful completion of all four stages.
Is 4 stage clearance required for non-licensed work?
Four stage clearance is required for licensed removal works. For notifiable non-licensed work (NNLW), a modified clearance process may be appropriate. We can advise on the correct approach for your specific situation.
Do you provide clearance certificates for compliance records?
Yes. Every successful clearance results in a formal Certificate for Reoccupation. This document forms part of your compliance records and demonstrates that proper procedures were followed.
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