Lagging is thermal insulation applied to pipes, boilers, calorifiers and ducts, and asbestos lagging is the most hazardous material commonly found in buildings. It is friable by nature, it is often decades old and patched, and it lives in plant rooms, cellars and ceiling voids where maintenance people go. Work on it is licensable without argument, and damaged lagging is an emergency in the ordinary sense rather than a job to schedule.
What it looks like
A plaster like or fibrous covering, sometimes moulded in sections, sometimes wrapped in a painted canvas, often patched with different materials over the years. It crumbles at the breaks. Debris beneath a run of pipework is a warning sign in itself, because that debris is the material rather than dust from something else.
Why it is the top of the register
Friable material releases fibres with very little disturbance, and lagging is in places people work: behind access panels, above ceilings, along cellar runs. Every asbestos management plan should have it first, with the shortest re-inspection interval, clear labelling where appropriate, and an explicit instruction to every contractor working near it.
If it is damaged
Stop work, keep people out, close the area, and do not sweep or vacuum. Ordinary vacuum cleaners spread fibres. Get a licensed contractor to assess it. The duty holder also has to record what happened and review the plan, because damage that occurred once will occur again if the cause is still there.
Removal, or management
Removal is licensable: notification, a sealed enclosure under negative pressure, and an independent four stage clearance. Sound, sealed lagging that nobody disturbs can be managed instead, with labelling, a short re-inspection interval and information given to every trade. Which one is right is a risk assessment decision rather than a default.
Questions people ask about asbestos lagging
Is pipe lagging always asbestos?
No, and modern insulation is not. In a building of the right age, damaged lagging should be treated as asbestos until analysis says otherwise.
Can a plumber work near lagging?
Only knowing it is there and only where the work will not disturb it. That is why the duty holder must give information on location and condition to anyone liable to work on the fabric.
What does lagging removal cost?
It is priced per job from the enclosure, the notification period, the volume and the clearance, after a survey, rather than from any rate card.
Could an asbestos boiler or its pipework still be in place?
The boiler itself is unlikely to contain much, and what is around it very often does. The recurring items are rope seals and gaskets on the door and the flue joints, insulating board panels behind or beside the appliance, cement flue pipe runs, and lagging on the pipework where it leaves the boiler. In an older house with a back boiler or a converted solid fuel installation, all four can be present within a metre of each other. That is why a boiler replacement is refurbishment work: the survey happens before the old appliance comes out, and the heating engineer is not the person to make that call on the day.
What are asbestos insulation boards, and why are they treated so seriously?
Insulating board is a lightweight panel used for fire protection, ceiling tiles, soffits, panels around heaters and boilers, and infill in partitions, and it has a high proportion of fibre in a soft matrix, which is why it releases so readily. It looks like ordinary building board and that is the problem: drilling, cutting or breaking it is exactly what a joiner or an electrician would do without a second thought. Working on it is licensed work in most cases, and it is one of the products a refurbishment survey is looking for before anybody opens a wall.