Al 1953 pretended :
I have a garage with an old corrugated asbestos roof. The roof has a number
of small holes where the rain gets in. Also, a draught gets in through gaps
where the sheets overlap. Would expanding foam be suitable to plug these
gaps and holes?

Ordinary mortar works well on the larger holes, if the panel is cleaned
up a little first. Silicon frame sealant works well to stop both blown
rain and drafts, if forced into the overlap from the inside. Sometimes
it can help if the gap is prised apart gently to increase it, before
pushing the sealant in.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk