Zincalume or Galvanised?

[echnidna]

it stays shiny a lot longer than gal

[silentC]

That's why my roof is Dune Grey Colorbond. I wanted the look but the local airport gets a bit ancy about tin roofs.

[journeyman Mick]

That's why my roof is Dune Grey Colorbond. I wanted the look but the local airport gets a bit ancy about tin roofs.

Can't the pilots afford sunnies?

Mick

[silentC]

That's the stupid thing, they all wear those dark glasses that they get free when they graduate from flying school.

But then, I don't want them crashing into my house, so I did what I was told...

[Bleedin Thumb]

I'm nowhere near an airport but we aren't allowed shiny rooves (roofs?) either. Its so people living higher than you don't get their retina's blasted.

[Barry_White]

gal will last longer if you are near the coast

Not true Bob

[silentC]

I'm nowhere near an airport but we aren't allowed shiny rooves (roofs?) either. Its so people living higher than you don't get their retina's blasted.

I knew someone who had one of those A-frame houses that were popular in the 70's. The roof was tin and they were eventually forced to paint it after complaints from the neighbours who were getting blinded in the morning or afternoon (depending on which side of the house they lived).

[SilentButDeadly]

I've just started doing re-roof (Colourbond) and wall cladding (zincalume) on our house.

We wanted galvanised sheet walls mainly because of the aesthetic value (it fades out nicely) however:

1) galvanised iron is way more expensive than zincalume
2) galvanised iron does not come with a perforation/corrosion warranty like zincalume does...

Basically it was the former that nailed it for us.

Take the zincalume....

[Barry_White]

This is for the benefit of ytbc showing the difference of gal and zincalume after about 20 years of weathering.

[ytbc]

Is gal on the left?

[journeyman Mick]

Is gal on the left?

Yes

Mick

[Barry_White]

Is gal on the left?

As Mick said yes.

[ian]

the shack is now progressing - I am planning to clad it in corrugated iron - roof and walls - I have been told the galvanised iron is not as shiny as zincalume - or at least it isn't when gets older - any views on which is preferable? I would prefer something not to shiny as it is a bush block.

Things you need to know:

corrugated iron is what Blue Scope Lysaght calls Custom Orb® and Custom Blue Orb®

If you're happy to go with one of the Colourbond colours or Zincalume then you can use Custom Orb® which is available with a Base Metal thickness (BMT) of 0.42 or 0.48mm

if you must have galvanised (Lysaght calls it Zincform — zinc coated galvanised steel) you'll have to go for Custom Blue Orb® which has a BMT of 0.60 or 0.80mm

the base metal thickness directly translates to cost

don't forget that you can have any length sheet you want — usually the practicle limit is the length of the truck making the delivery — eliminating the end lap between sheets saves you money.

for most people, the difference in base metal thickness translates to the spacing of the batterns to which you screw it and hence the number of screws you need.

be sure to get the battern and screw spacing right for your area


ian

[Barry_White]

if you must have galvanised (Lysaght calls it Zincform — zinc coated galvanised steel) you'll have to go for Custom Blue Orb® which has a BMT of 0.60 or 0.80mm

ian

Ian

As far as I know up to three and a half years ago Lysaght were still rolling 0.42 BMT Zincform Custom Orb Hi-Tensile. The Custom Blue Orb is used for curving such as Bullnose or for water tanks.

The Custom Orb in zincform 0.42 is used as normal roofing and they also keep it for roofing on intensive farming such as piggery's and poultry sheds.

Blue Orb has a tensile strength of G300 and Hi-Tensile Custom Orb steel has a tensile strength of G550.

There is also a difference of the coating classes of the two steels.
Custom Orb Z/L has a coating class of AZ150 which is 150 grams of coating to the m2
Custom Orb Gal has a coating class of Z450
Custom Blue Orb Z/L has a coating class of AZ 150 and AZ200
Custom Blue Orb Gal has a coating class of Z600

The reason the gal has a heavier coating because the life of gal is directly related to the thickness of the coating whereas with Zincalume the coating thickness has mainly no bearing on the life of the zincalume.

[ian]

Barry

Through a coleague at work I've obtained a copy of Lysaght's latest Referee.

It lists Zincform as an available finish for 0.60 and 0.80 Custom Blue Orb but not for the thinner 0.42 or 0.48 Custom Orb.
But you can have stainless steel in 0.42mm Custom orb for your piggery if you want


ian