Encapsulation, or asbestos sealing, means sealing asbestos containing material in place so that it cannot release fibres, rather than taking it out. It is a recognised and often preferable answer for material in good condition, because removal is itself a disturbance and the moment of highest risk. It is not a way of forgetting about the material: an encapsulated item stays on the register, keeps its re-inspection interval, and has to be pointed out to anybody working near it.
What encapsulating asbestos involves
Depending on the material it may be a coating applied over the surface, an impregnating sealant, or a physical enclosure such as boarding over. The point is that the surface can no longer shed fibres and cannot be casually damaged. For sprayed coatings and lagging this is specialist licensable work; for a cement roof or a textured ceiling it is often straightforward.
When to encapsulate asbestos rather than remove it
When the material is in good condition, when it is not in the way of planned work, when removal would mean stripping out large parts of a working building, and when the alternative is a poorly executed removal. Encapsulating a sound textured ceiling by overboarding is quicker, cheaper and safer than scraping it, and it produces no hazardous waste.
When it is not
When the material is already damaged or friable, when the building is being refurbished or demolished so the work will reach it anyway, and when the material is somewhere that will keep being disturbed. Sealing a ceiling that a contractor will drill through next year defers the problem into somebody else's hands.
What you owe afterwards
The register records that the material is still there and now sealed, with the date and what was done. The risk assessment is reviewed, a re-inspection interval is set for the encapsulation itself, and every contractor working near it is told. Encapsulation without a record is how a building loses track of what is behind its own walls.
Sprayed asbestos coatings: how to identify and manage them
HSE's survey guide describes them as coatings sprayed or trowelled onto steel and concrete beams and columns as fireproofing, and onto the undersides of floors and roofs for fire, thermal, anti-condensation and acoustic insulation, in high-rise blocks, warehouses, factories, theatres and halls. They are usually 55 to 85% asbestos in a Portland cement binder, were applied until 1974, can be 10 to 150 mm thick, and overspray onto the surfaces around the target is common. They are among the materials HSE classes as normally licensed, and its material assessment scores sprayed asbestos in the highest product category, because an unsealed spray sheds fibres when knocked, abraded or delaminating after a leak. Managing one means a survey and laboratory analysis to confirm it, a record of its condition on the register, keeping people and work away from it, and leaving any sealing, repair or removal to a licensed contractor.
Questions people ask about asbestos encapsulation
What is the definition of encapsulated asbestos?
Asbestos containing material that has been left in place and sealed, by a coating, an impregnating sealant or an enclosure, so that its surface cannot release fibres or be casually damaged. It is still asbestos, it stays on the register, and it is reinspected like any other.
Can you encapsulate asbestos with paint?
For some materials, yes. HSE lists painting or repainting asbestos insulating board in good condition, and encapsulation and sealing in of asbestos materials in good condition, as non-licensed work. Paint over damaged or friable material seals nothing, and the work still needs a risk assessment and trained people.
Is encapsulation cheaper than removal?
Usually, and it also avoids the hazardous waste and the disruption. The saving is real, and it comes with the obligation to keep managing what is still there.
Can any asbestos be encapsulated?
Material in good condition and unlikely to be disturbed is the candidate. Damaged, friable or crumbling material is normally a removal question, and sprayed coatings and lagging are licensable work either way.
Does encapsulated asbestos have to be declared when selling?
There is no duty to remove it, and a buyer's surveyor will normally ask. Handing over the register and the encapsulation record is the straightforward answer and it usually helps rather than hinders.
Can textured ceiling asbestos be encapsulated?
Often, and simply. Overboarding a sound textured ceiling is quicker, cheaper and safer than scraping it, and it produces no hazardous waste. The ceiling stays on the register afterwards and is pointed out to anybody working near it.
Can sprayed asbestos be encapsulated?
It can be, but for sprayed coatings and lagging encapsulation is specialist licensable work, just as removal would be. Sprayed material that is already damaged or friable is normally a removal question.