Repairing a corrugated asbestos-cement roof

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?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Depends a bit on the aesthetics, patched in cement/asbestos roofs tend to l ook crap. If that is not an issue then a lot depends on how long you want t he repair to last because inevitably you will end up repairing it again. Th ose roofs tend to weather over time the eventual surface does not provide t he best substrate to adhere on and being the material it is not really feas ible to clean it.
Richard
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 19:25, Tricky Dicky wrote:

I plan to wire brush it (wearing mask and working up-wind) around the damaged areas, then to seal it with either a PU varnish or proprietary primer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hmm, well, its actually not that dangerous, as its particles not fibres, bout the kind of dimpling it has on its surface seem not to be able to be removed and if you do it seems that its still powdery underneath. I guess some modern paints might be better though. Brian
--
----- --
This newsgroup posting comes to you directly from...
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@aolbin.com was thinking very hard :

Box section, corrugated painted metal roof as a replacement, it is not that expensive.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 19:28, Harry Bloomfield wrote:

I've already re-roofed one smaller shed with 32/1000, but this one is LARGE (an old chicken house).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 19:28, Harry Bloomfield wrote:

Drips condensation during cold weather though.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew formulated the question :

As does asbestos. Steel can be fixed by either buying the insulated version, or adding insulation.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 19:08, snipped-for-privacy@aolbin.com wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 19:30, newshound wrote:

Why would you prefer Denso tape to flashband?
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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 13 Jan 2019 20:38:21 +0000, snipped-for-privacy@aolbin.com wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 14/01/2019 07:35, Thomas Prufer wrote:

Thanks for that. I'll think about using GRP on the top.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 13/01/2019 20:38, snipped-for-privacy@aolbin.com wrote:

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

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 14/01/2019 15:02, newshound wrote:

Yes, roofing bolts to hold the wiggly tin. Perhaps a bit of GRP over the top.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sunday, 13 January 2019 19:09:00 UTC, snipped-for-privacy@aolbin.com wrote:

I fixed mine with flashband. The stuff lasts a long time.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The problem with this stuff is that as the building settles, the roof is under stress and fixing cracks etc, is only postponing the inevitable. I think it goes brittle with age myself. The only, not very pretty thing I did for some years till I was ready to let it go was to use plastic corrugated stuff over it, tucked under the apex strip. Fillers, glue and other clever things seem not to bond to the powdering asbestos very well. Brian
--
----- --
This newsgroup posting comes to you directly from...
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sunday, 13 January 2019 19:09:00 UTC, snipped-for-privacy@aolbin.com wrote:

If replacement isn't practical, a cheap effective option is: Apply bitumen paint Apply cloth Apply bitumen paint Sprinkle on sand.
NT
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.