On 04/08/2020 11:10, TimW wrote:
This is an ordinary timber garden shed 8' x 10' (2.4m x 3m), the roof is
felt on treated sw boards on 3x2 purlins, a central ridge and a shallow
pitch of maybe 15deg. Very standard cheap wooden shed. Over 20 yrs I
have refelted and half re felted and it's leaking again, and the soffit
boards are totally rotted. The rest of the shed is of no particular
quality, and a a bit wobbly.

I was thinking of covering the roof with something better, hoping to
extend its life and usefulness - what would be good? Onduline?
galvanised steel? plywood and a rubber type sheet? some kind of new
material?

TW

IIRC the cheapest long-lived thing per square foot are the thin steel
plastic coated box profile sheets, but you might have to bodge the
ridge. If the boards are not too bad you could probably fit the sheets
using sticks like **** type cartridge adhesive, and save messing around
with roofing nails or screws.

I have to replace a corruline/onduline pitched roof soon, I shall
probably board it first but have not decided whether to use metal or
corruline. I have come to the conclusion that it is *only* worth using
the corrugated bitumen boards with full boarding underneath. Mine lasted
20 years but a stables that I rent has only lasted 10, owing to sagging
and splitting between rafters and purlins.