Bitumen is a binder, and asbestos fibre was added to a great many bitumen products for strength and heat resistance: floor tile adhesives, roofing felts, damp proof membranes, mastics, sealants and coatings. The black tarry adhesive under old floor tiles is the one most people meet, and it is a separate material from the tile above it, sampled separately and often present when the tile itself is clear.
Where it turns up
Under vinyl and thermoplastic floor tiles as a bedding adhesive. In built up flat roof felts and their bonding compounds. In damp proof courses and tanking. In gutter and flashing mastics. In sealants around windows and services. It is usually black or very dark brown, tarry, and stuck hard to whatever it was bonding.
Why the adhesive is the part that is missed
Tiles lift and the adhesive stays. A floor fitter scrapes, sands or heats it to get a level surface, and that is the disturbance. Sampling the tile alone produces a certificate about the tile, which is why a competent survey samples the bed as well and why a clean tile result is not permission to grind the floor.
Roofing felts
Bituminous roofing felts and their bonding compounds were made with asbestos fibre, so an old flat roof build up can contain it as well as the sheeting on a pitched one. Stripping a flat roof of the right age is a disturbance, and it belongs in the roofing quote as an identified material rather than as a discovery on the day.
How it is handled
Removal is usually non-licensed work and often notifiable non-licensed work depending on the method. It is taken up cold and mechanically rather than ground, sanded or burned off, and the arisings are hazardous waste. Heat guns soften bitumen and also drive off fumes, and grinders turn the residue into exactly the dust the rules exist to prevent.
Questions people ask about bitumen asbestos
Does bitumen contain asbestos?
Some bitumen products did and many did not. Age and product type raise the question, and only analysis of the actual material answers it.
Is the black glue under my floor tiles dangerous?
Left in place and covered it is not releasing anything. Grinding or sanding it is the act that matters, which is why it is identified before a floor is prepared.
Can I lay a new floor over bitumen adhesive?
Laying over a sound bed is a normal way of managing it, and it has to be recorded so whoever lifts the floor next knows what is under it.