noncombustible

The materials used are non-combustible and water-proof, and will wear indefinitely.

For five miles they had laid a blanket of non-combustible gases.

This will not apply to concealed work in walls or ceilings composed of concrete, tile or other non-combustible material.

Asbestos is merely a non-combustible material in which air may be entrapped, but, when non-porous, is a good conductor of heat.