New Leak Testing Guidance for Asbestos Removal: What It Means for Your Project
New leak testing guidance for asbestos removal: what it means for your project
New guidance published in August 2026 makes it much clearer when leak testing should be carried out during licensed asbestos removal, and what should happen if something goes wrong.
When asbestos is removed from a building, the work takes place inside a sealed enclosure kept under negative pressure, so that fibres stay inside. But how do you know the enclosure is actually working? That’s where leak testing comes in.
Here’s what’s changed, and what it means if you’re planning asbestos removal works.
At a glance
- New industry guidance on leak testing was published on 21 August 2026.
- Licensed contractors must decide, through a risk assessment, whether leak testing is needed, where, and how often.
- Any decision not to leak test must be recorded and justified in the plan of work.
- Results above 0.010 fibres per millilitre mean work stops and the enclosure is investigated.
What’s been published?
On 21 August 2026, the Asbestos Network Technical Working Group published new guidance for licensed asbestos removal contractors. The working group brings together industry experts, HSE representatives and trade associations, and its guidance is used across the licensed asbestos removal industry.
The requirement to prevent the spread of asbestos isn’t new. It sits in Regulation 16 of the Control of Asbestos Regulations 2012, and the Approved Code of Practice (L143) already expects air monitoring outside enclosures, particularly in occupied buildings. For several years, though, leak testing had become far less common on site. The new guidance sets out clearly when it’s needed and how it should be planned.
What is leak testing?
Leak testing means taking air samples outside the asbestos enclosure while removal work is under way, to check that no fibres are escaping. Samples are typically taken around the enclosure itself, at airlocks and bag locks, where pipes and services pass through, and at the point where the negative pressure unit (NPU) discharges its filtered air.
It gives an early warning of a problem that visual checks and smoke tests might not pick up, and reassurance to everyone, from the contractor and the client to the regulator, that the enclosure is doing its job.
When is leak testing needed?
Under the new guidance, the licensed contractor decides whether leak testing is needed, and where and how often, based on a risk assessment. The guidance says leak testing should be carried out:
- Always where the negative pressure unit vents inside the building, with testing at the discharge point
- Where areas near the enclosure are occupied by anyone other than the removal team, analysts, auditors or HSE inspectors
- In sensitive buildings such as schools, hospitals, care homes and 24-hour control rooms
- During higher-risk tasks, such as removing sprayed coatings, pipe lagging or asbestos insulating board that may break up
It also asks contractors to think about how fibres could travel if an enclosure failed: through shared ventilation, corridors, stairwells, ceiling voids or risers.
A decision not to leak test must now be specifically recorded and justified in the plan of work, and a history of low results is not a reason to stop testing.
What happens if a result is high?
Any result above this level should be investigated immediately. Work stops while the enclosure is inspected, the NPU’s pressure and airflow are checked, and a smoke test is carried out after any repairs.
The area is then resampled as soon as work restarts. If readings are still elevated, work stops again until the source is found.
Where does UKAS come in?
Under Regulation 20 of the Control of Asbestos Regulations 2012, air monitoring has to be carried out by an organisation accredited to ISO/IEC 17025, which in the UK means UKAS accreditation. The sampling itself follows the HSE’s Asbestos: The Analysts’ Guide (HSG248). So leak tests should be carried out by a UKAS-accredited analyst, planned in advance with the contractor and the client.
What does this mean for you?
If you manage a school, a housing portfolio, offices or any occupied building, you can expect leak testing to be part of most licensed asbestos removal projects from now on. In practice, that means:
- Plan it early: leak testing should be designed into the job alongside the enclosure and air management, not added at the last minute.
- Check the plan of work: it should say where and how often leak testing will happen, or explain clearly why it isn’t needed.
- Allow for it: additional air testing can affect the programme and cost, so it’s best discussed at quotation stage.
- Ask questions: a good contractor will be happy to talk you through their leak testing strategy.
How SAR can help
At Safe Asbestos Removal Ltd, we plan leak testing into our risk assessments and plans of work from the outset, working with independent UKAS-accredited analysts. That keeps your building, staff, tenants and pupils protected throughout the job. If you have a project coming up, or you’d like advice on what the new guidance means for your building, get in touch.
Planning asbestos removal works?
Talk to us about your project and how leak testing will be planned into the work. We’re available by phone, email, WhatsApp or our enquiry form, and we look forward to helping you.