On Sun, 12 Nov 2017 04:51:54 -0800 (PST),
wrote:

Secondly, do materials containing *any* detectable asbestos require specialist, expensive disposal, or is there a threshold amount beyond which the requirement is triggered?

If it was roof tiles it would have been asbestos cement. This does
not require specialist contractors for removal but the disposal costs
may be higher than for general waste.