DIYbanter - View Single Post - Repairing a corrugated asbestos-cement roof

newshound

On 13/01/2019 20:38, wrote:
On 13/01/2019 19:30, newshound wrote:
On 13/01/2019 19:08, wrote:
I have a large shed (far too large to consider re-roofing) which has
a corrugated asbestos-cement roof that probably dates from the 60s.
It's in quite good condition but there are a couple of cracks and one
4" hole where a pipe used to pass through.
It seems the repair options are either Flashband (+primer), an EPDM
patch, making a GRP patch, covering with a bit of corrugated roofing,
or using galvanised mesh and cement. What else should I be thinking
of? Any recommendations?

Rather than flashband I would be thinking about the fabric with mastic
tapes, Sylglas to DIY-ers or Denso tape to professionals. Together
with a bit of corrugated sheet of the correct pitch for the 4 inch
hole. Probably not galvanised mesh plus cement, too likely to crack
over time.

Why would you prefer Denso tape to flashband?

Because I think you would get it to stick much better to the irregular
and friable surface.

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'd agree with that, except that stixall might well be enough. What are
you going to screw it to? Or do you mean put a few nuts and bolts
through the two layers? I would be OK with that. The problem I can see
with filling the depression with car body filler is that I am sure
cracks will open up. As an alternative, how about filling the depression
with mastic? The main thing is to get a good fillet over the lap joints.
Or, as I said, sylglas or denso.