Asbestos encapsulation and sealing
Asbestos encapsulation seals intact, non-friable asbestos-containing materials in place using a penetrating or surface-applied encapsulant, preventing fibre release without disturbing the material. It is appropriate for specific situations — and we will tell you honestly whether it is the right option for your property or whether removal is the cleaner long-term solution.
What we encapsulate — and what we do not
Not sure which category your material falls into? A management survey will confirm the material type and condition before any decision is made.
What is asbestos encapsulation?
Sealing asbestos in place: what it means and when it applies
Asbestos encapsulation is the application of a sealant or physical barrier over an asbestos-containing material (ACM) to prevent fibre release. It does not remove the asbestos — it manages it in place. Under CAR 2012, encapsulation of ACMs in good condition is classified as non-licensed work, provided fibre release remains below the control limit of 0.1 fibres/cm³.
The HSE's guidance on deciding whether work requires a licence explicitly lists "encapsulation or sealing-in asbestos that is in good condition" as an example of non-licensed work. This means that for intact, non-friable materials — asbestos cement, Artex, floor tiles — encapsulation can be carried out by a UKATA-trained operative without an HSE licence.
The critical qualifier is condition. Encapsulation is only appropriate when the ACM is firmly adhering to its substrate, shows no signs of damage or delamination, and is in a location where it will not be disturbed by future maintenance or building work. When those conditions are not met, removal is the correct course of action — and we will tell you so.
Encapsulation methods
Three approaches — matched to the material and location
The correct encapsulation method depends on the type of ACM, its condition, its location, and the level of protection required. We assess all of these during the free site survey before recommending an approach.
Penetrating encapsulant
A low-viscosity liquid sealant that penetrates the surface of the ACM and binds fibres from within. Suitable for porous materials such as Artex and asbestos cement in good condition. Applied by brush or spray.
High-build elastomeric coating
A thick, flexible coating applied in multiple layers over the ACM surface. Provides impact resistance and a durable barrier. Can incorporate a reinforcing membrane (calico or scrim) for additional protection.
Mechanical over-boarding
Physical encapsulation by fixing a new layer of board or sheet material over the ACM. No drilling through the asbestos material unless the risk assessment confirms it is safe to do so with appropriate controls.
Method selection follows the ARCA Guidance Note GN010 on encapsulation of asbestos-containing materials, which sets out the technical requirements for each approach.
When encapsulation is not appropriate
Six situations where we recommend removal instead
Encapsulation is not a universal solution. There are specific situations where it is technically inappropriate, creates a greater long-term liability than removal, or is simply not permitted under the regulations. We will identify these during the site survey and advise accordingly.
The management obligation encapsulation creates
This is the point most contractors do not explain clearly: encapsulation does not end your responsibility for the asbestos. It transfers it into an ongoing management obligation.
Under CAR 2012 Regulation 4, once a material has been encapsulated, it must be recorded in the asbestos register, monitored at regular intervals, and any contractor working near it must be informed of its presence and condition.
For commercial properties, this is a legal requirement. For domestic properties, it is strongly advisable — particularly if you plan to sell, let, or carry out further building work.
Not sure which option is right?
Our guide Removal vs Encapsulation: Which Is Right? sets out the decision criteria in detail. Or call us and we will advise based on your specific material and situation.
Call 07344 860932 →From our work
The Lewisham landlord who chose encapsulation — and why it cost more in the end
A landlord in Lewisham contacted us about an asbestos cement garage roof on a rental property. He had received two quotes: one for removal at around £1,400, and one for encapsulation at £480. He chose encapsulation and had it done by another contractor. Three years later, he called us.
The encapsulant had failed at the ridge. Water had got in behind the coating, saturated the cement sheets, and the material was now damaged, delaminating at the edges, and — critically — no longer in the "good condition" that makes encapsulation non-licensed work. The sheets now required removal, but the failed encapsulant had to be treated as a complication: it had to be assessed, the method statement revised, and the waste classified accordingly.
The removal cost £1,800 — more than the original removal quote, plus the £480 he had already spent. He also had three years of management obligation on his asbestos register that he had not been told about when the encapsulation was done.
We are not saying encapsulation is never the right answer. For a commercial property with an intact asbestos cement ceiling in a low-traffic plant room, where removal would require significant structural work, encapsulation with an elastomeric coating and a proper management plan is entirely appropriate. But for a domestic garage roof in South East London — a material that is regularly exposed to the weather, subject to thermal movement, and often in marginal condition to begin with — removal is almost always the better long-term decision.
We tell every customer this before we quote. Some still choose encapsulation, and we carry it out properly when they do. But we will not recommend it when the numbers and the material condition point the other way.
Our process
How we carry out an encapsulation job
Site survey and assessment
We visit the property, assess the ACM condition, confirm the material type (sampling if required), and advise on whether encapsulation or removal is the appropriate option.
Method statement and COSHH assessment
We prepare a written method statement and COSHH assessment for the encapsulation work, specifying the encapsulant product, application method, and RPE requirements.
Encapsulation works
Our UKATA-trained operatives apply the encapsulant using the agreed method. The area is isolated during application. Waste materials (brushes, PPE) are disposed of as asbestos waste.
Register update and handover
We provide a written record of the encapsulation for your asbestos register: date, method, product, and re-inspection recommendation. You receive this before we leave site.
Why Diamond
We advise on the right option, not the easier sale
Encapsulation is often quoted as the cheaper option. In the short term, it usually is. But the ongoing management obligation, the risk of encapsulant failure, and the possibility that future building work will require removal anyway mean that the total cost of encapsulation can exceed removal over a five-to-ten year period.
We are a small South East London contractor. Our business depends on repeat work and referrals, not on selling the cheapest option on the day. When removal is the right answer, we say so — and we quote for it transparently.
Pricing factors for encapsulation
Frequently asked questions
Not sure whether to encapsulate or remove?
We will assess the material, give you an honest recommendation, and quote for both options if appropriate. Free site survey, no obligation.
Or read our guide: Removal vs Encapsulation — Which Is Right?