Asbestos in old mastic and sealant

Where it can turn up

• Mastic round older window and door frames.
• Joints between precast concrete or cladding panels.
• Old bitumen-based mastics, putties and sealants round roof lights, gutters and flashings.
• Sealants in older plant rooms and ductwork.

Why not just cut it out?

Mastic that is intact and left alone is low risk. Cutting, grinding or scraping it can release fibres. You cannot tell by looking whether a sealant contains asbestos: it needs testing by a laboratory.

What to do

1. For a commercial or other non-domestic building, check the asbestos register: the duty holder has to manage asbestos under the Control of Asbestos Regulations 2012.
2. For a home, or if the register does not cover the material, have a sample tested before work starts.
3. If it contains asbestos, the work must be done by people with the right training, and some work must be done by a contractor licensed by the HSE. The HSE website explains which work is which.
4. When you post on this site, tick the possible-asbestos box. Applicators see a warning on the job.

If the test is clear

The job is a normal reseal. Post it with photos and the test result noted in the description.

Quick answers

Is all old mastic asbestos?

No. Many old sealants contain none. The only way to know is to test it.

Will applicators still see my job if I tick possible asbestos?

Yes. Every applicator who covers your area sees it, with a clear warning to test before disturbing the material.