Asbestos encapsulation, done by the book.

Worried about an old asbestos cement roof?

You are not alone, and an asbestos cement roof is not automatically an emergency. Many garages, sheds, workshops and farm buildings built before 2000 have corrugated cement sheets that may contain asbestos.

Owners usually come to me worried about two things: the risk, and the cost and disruption of removal, disposal and a new roof. They want to know if there is a safe, sensible way to keep what they have. Sometimes there is. Sometimes there isn't. The only way to know is to find out properly what the material is and what condition it is in.

Why must there be an asbestos survey first?

Because you cannot tell whether a material contains asbestos, or whether it is safe to coat, just by looking at it. A qualified asbestos surveyor identifies the material, usually by taking samples for laboratory analysis, and records its condition.

HSE guidance is clear on the principle: asbestos that is in good condition and unlikely to be damaged or disturbed is often safer left in place and managed. Material that is damaged, or will be disturbed by future work, may need to be repaired, sealed, enclosed or removed, depending on its condition.

I don't carry out asbestos surveys and I don't remove asbestos. If you don't already have a survey, I will explain what to ask for. If the survey says removal is the right route, that is a job for a suitably qualified asbestos contractor, and I will tell you so.

What is cork encapsulation?

Encapsulation means sealing a sound asbestos-containing material in place with a protective coating, so its surface is protected from weathering and further wear. The asbestos is not removed.

A cork coating forms a continuous, flexible, weather-resistant skin over the sheets. For it to be part of an encapsulation approach, three things have to be true:

1. The survey and assessment confirm the material is suitable to remain in place.
2. The chosen product is documented as appropriate for encapsulating that material and application.
3. The surface can be prepared without disturbing it, using methods that follow HSE guidance. That means no abrasive cleaning, no pressure washing and no drilling.

If any of those is not met, encapsulation is not the right answer. I am a SprayCork UK approved applicator, and I only propose this where all three are in place.

Is encapsulation better than removal?

Neither is always better. Encapsulation usually costs less upfront and causes less disruption, but it leaves the asbestos in place, so it needs managing for as long as the building stands.

These need comparing for your building. Future plans matter too: if you expect to extend, convert or demolish, removal may make more sense now.

What happens during an encapsulation job?

The work is planned around one rule: don't disturb the asbestos. Everything from access to cleaning is chosen with that in mind.

• Safe access. Asbestos cement sheets are fragile and must never be walked on directly. Roof work is planned with suitable access equipment, and that cost is shown in your quote.
• Gentle preparation. Loose dirt and growth are dealt with using methods that follow HSE guidance for asbestos cement, never abrasive tools or pressure washers.
• Coating. The cork system is applied in coats to the product's specification, in dry weather, to form a continuous skin.
• Records. You receive details of the work, the product and the date, ready for your asbestos records.

The same coating is used on sound roofs without asbestos too; see cork roof coating and the spray cork overview. For textured ceilings inside the house, read plastering over Artex instead.

What do commercial property owners need to know?

If you own or manage non-domestic premises, you have a legal duty to manage asbestos under the Control of Asbestos Regulations 2012. Encapsulation does not end that duty.

• The encapsulated material stays on your asbestos register, with its location and condition.
• Your asbestos management plan should record the work, the product used and the date.
• The material is reinspected at intervals set by your plan.
• Anyone who might disturb it, such as roofers, electricians or solar installers, must be told before they start.

For homes, the duty to manage does not apply in the same way, but it is still wise to keep the survey and coating records and pass them on to future buyers and tradespeople.