On Sun, 13 Jan 2019 20:38:21 +0000, wrote:

Currently, for the hole, I'm favouring a corrugated off-cut screwed and
Stixall'd to the inside and then the depression at the top filled and
profiled with polyester resin (car body filler) ... but all suggestions
welcomed, especially from those who've already solved the same problem.

I repaired a difficult-to-replace bit of asbestos cement roofing with fiberglass
mats and resin, as used to repair rust holes cars. This soaked into the cement
well, creating a good bond, and has lasted ~10 years so far. Came in a kit with
resin, hardener, and mats...


Thomas Prufer