"Marland" wrote in message
...
wrote:
On Monday, 22 April 2019 22:56:20 UTC+1, newshound wrote:
On 22/04/2019 21:48, tabbypurr wrote:
On Monday, 22 April 2019 20:10:25 UTC+1, Bill wrote:
In message , tony sayer
writes

However now that the damage has been done thin "ish" section Steel
cold
dipped galvanised roof trusses and a coated ally roof materials .

Surely you mean hot dipped galvanised?

Painted to protect it from acid and sulphides in rain, that should
last
for ever.
Not totally sure about coated ally, having had two Land Rovers.

'Well we tried to cold dip it, but encountered some resistance'

Galv is good but no hope of it lasting a century, let alone several.


NT


What do you think is going to happen to proper hot dip galvanised struts
inside the dry roof space?

condensation.


A lot of people judge the effectiveness of galvanising by the state of
galvanised Iron Sheets on a barn or shed after a couple decades. What
has
often happened with them was the coating was damaged upon installation by
nails banged through them or rough handling exposing the steel underneath.
Handled properly it should last a really long time

Yeah, no rust in my metal decking except where the bleed from the
evaporative air cooler gets on it and that water is very salty because
the cooler by its evaporative action concentrates the salt in the water.
Thats why the bleed is there. Thats been there for 45 years now.

Metal decking doesnt have any nails thru it, its got galvanised
clips under the decking that are nailed to the rafters and the
decking interlocks with each sheet and it button punched so
that the vertical ribs in the decking grip the clips underneath.

but in a large building it would be inevitable that eventually some
tradesmen would drill a hole for a cable,pipe or to fasten something.