Leaking asbestos garage roof

[jamesdean1986]

Firstly I just want to say that I already know the dangers of asbestos and how to handle it due to removing it from my house last year.
At the front and back of the garage, the mortar has come away from the edge and down the sides all the flashing has cracked open by about 3-4mm.
Structurally everything is good, although it is an old garage, so I'm at the dilemma of do I replace the whole roof (initial thought is bitumen sheets) or do I repair roof, presumably with new flashing and mortar?

 

[dogfonos]

I have a similar issue with an asbestos/cement garage roof although no obvious leaks. There have been quite a few similar threads on this forum and opinion seems split between complete roof replacement and applying a coating (depends in part on roof condition of course).

I've decided on complete replacement. One thing puzzles me: why is it that bitumen sheets are often suggested as a replacement but not new, cement based corregated sheets? Are modern cement based sheets a bad idea as a replacement?

 

[jamesdean1986]

I have to be honest, I didn't think they made cement ones any more.
From my point of view, probably two reasons I would not use them.
I suspect (but haven't checked) that the bitumen sheets are a lot cheaper. 10 large sheets of bitumen when I last checked could be picked up for around £100-120. Wood for supports, plus flashing etc. whole roof was working out to about £200 - thats not including disposal of the old sheet.
Second reason for me, is I will probably be doing the majority of this roof on my own and putting up cement sheets will probably be a lot harder to handle.
However I do lack some faith in the bitumen sheets, by way of how much extra support they require to stop sagging.

 

[ed110220]

I have to be honest, I didn't think they made cement ones any more.
From my point of view, probably two reasons I would not use them.
I suspect (but haven't checked) that the bitumen sheets are a lot cheaper. 10 large sheets of bitumen when I last checked could be picked up for around £100-120. Wood for supports, plus flashing etc. whole roof was working out to about £200 - thats not including disposal of the old sheet.
Second reason for me, is I will probably be doing the majority of this roof on my own and putting up cement sheets will probably be a lot harder to handle.
However I do lack some faith in the bitumen sheets, by way of how much extra support they require to stop sagging.

Marley Eternit still make fibre cement profiled sheeting. It looks a lot like asbestos cement, but does not contain asbestos. It's mainly used for commercial and agricultural buildings. I guess for small structures like sheds and garages most people prefer the convenience of bitumen sheeting even if it doesn't last as long.