Chrysotile roofing sheets should never be subject to loading.
The best solution is to re-roof it with onduline or twinwall etc.
- Buy some large bolt croppers
- Crop all the (usual) J-bolts from below
- Wear any N95 mask, wet the sheets above & below
- Slide the roofing sheets off, then prepare for disposal (*)
- Fit new roofing sheets
(*) Disposal is according to your council website: Some have a pre-defined waste site, not the general site. You turn up on a particular day with a piece, double bagged & taped. They then approve its disposal, try to pick a piece with Chrysotile visible.
(*) Breakage should be painted with any scrap oil or latex paint: Breaking a panel releases few fibres due to high cement content, however care must be taken to not allow broken edges to act as a fire against one another and likewise never drill, holesaw, saw or smash panels. Painting any broken edges with any scrap oil or latex paint is considered normal - many garage walls are adorned with scrap paint from brush cleaning and sealing any broken side panels. Oil paint is effective on cement, try removing oil paint from brickwork :-)
Cowboy asbestos disposal companies.
- Usually claim the asbestos sheet is something else
- Provide false material proof from pocket to you & insurers
- Make a pigs ear of it, cost insurers 12-20k, then sued
- The profit from many outweighs the litigation from some.
If the frame underneath is 40yr old rusty steel beware it will collapse as much as the chrysotile break. Remove the side-panels by angle-grinder on the *steel side* only after removing the roof sheets. The reason is the side panels may actually be all that is holding it up. Some people rebuild by bolting together 0.125" thick 1.5" L-angle aluminium, somewhat like a garden centre or greenhouse. A considerable amount of cross-bracing is required since modern cladding does not contribute much rigidity to the structure unlike Chrysotile. There are black recycled plastic agricultural panels available (Agriboard?) which would make useful side cladding (infill panels) which are relatively strong & cheap compared to alternatives.
What if you want to spread this out over a few years re cost/time/ hassle? No problem, work from one end and progress accordingly - working from below, never above (no need).
N95 mask, spray wet from above & below, crop the J bolts, simply lift off the panels, old oil paint any suspect edges before removal if bothered. Remember you have been walking around and inside the thing for years, slamming the door :-)