"newshound" wrote in message
o.uk...
On 10/05/2021 11:27, cf-leeds wrote:
I need to replace a very leaky old garage roof, which is currently in
corrugated asbestos sheets (I think they're asbestos anyway). I'm aware
of the disposal process for old asbestos roof and I have details of the
local council disposal process for asbestos - I'm ok with all that.

My question is what's the best replacement for the roof.

It's a flat sloping roof with a single gutter across the back end of the
garage - It's a prefab garage. (not a pitch roof).

I thought I'd just look online for some galvanised corrugated metal
sheets, around the same dimensions at the old asbestos, but I find there
are many products out there, including corrugated bitumen sheets.

Can anyone offer some advice on a good option here.

My main criteria are, easy to install, good-value, long lasting in terms
of no discolouring, if they happen to be dark great for example. Is there
anything that you'd definitely avoid ?

Any tips welcome.

Thanks in advance.

The problem with Onduline or Wickes own brand corrugated bitumen is that
it is only rated for 10 years life, especially if the slope is shallow or
the purlin spacing large. I need to replace my shed's roof this year,
admittedly that lasted 25 years, but we rent a stables where it has failed
badly at 10 years. Basically, it sags and then tears. It will certainly
last longer if you board underneath it with sterling board. I have not
quite decided whether to do that with mine, or whether to convert to
plastic coated steel, or perhaps to corrugated fibreglass (which is a bit
more expensive).

It gets slightly lighter in colour over time, not enough to matter IMHO.

Metal sheet comes in a range of thicknesses and geometries. The thinnest
(eBay) lasts pretty well, it is light and pretty easy to cut and fix. If
in a windy area you need to make sure the edges are well fixed down.

imo metal decking works much better. Happy with a very low slope
and since the clips are attached to the rafters first, well retained after
you button punch the decking onto the retaining clips. Lasts much
longer than anything else except stuff like copper or zinc sheet.