Guttering - Metal or plastic?

[LotteBum]

When we did our roof and guttering, the roofing guy said that even if we were going to paint our gutters to still use Colorbond. He said that they were more durable than Zincalume, but also said that a Zincalume roof is much the same as Colorbond, because water doesn't pool.

Anyway, that's just what we were told. Best of luck with it.

Lotte

[tameriska]

(which would be plain gutters all round, and with a tin roof .

Do you know if your tin roof is Galvanised or Zinc iron.

From what I have heard, for longevity, it is better to match galv with galv, and zinc with zinc.
I have heard of a Zinc roof paired with a Galv tank, the galv tank rusting out earlier than if it had been paired with a galv roof. Something to do with a reaction with the water running off one metal into another.
I am sure that other forum members will be able to explain better than I have, as this is only something I was told from a builder a few years ago.

[demuire]

I have no idea, it's silver I've decided to go the colorbond gutters though, so no worries (I guess?)

[Barry_White]

As an old Lysaght Rep and manager here is the correct information on Zinc (or Gal in the laymans terms), Zincalume and Colorbond.

Zinc or Gal is the old finish which its life span is governed by the thickness of the coating on the surface. Prior to the advent of Zincalume there was some Colorbonded Gal based material around as well as some imported material. Gal coated roofing was phased out about 25 years ago but there was still a bit of Gal feed used in guttering for a bit longer.

Old Gal is distinquised by the dull dark grey appearance from weathering that takes place after being exposed to the elements for about six months. The life of gal is about 50 + years before it begins to show signs of corrosion.

Zincalume is an aluminium/zinc based coating that is far superior to the old gal and the thickness of the coating has no bearing on the length of time it will last. The life of Zincalume from accelerated testing was said to last at least four times as long as Gal and even up to eight times as long inland from the coastal invironment. The only downside of Zincalume is you can't have water running off the old lead flashings on to it because it will create corrosion. The appearance of Zincalume is of a shiney silver surface and does not dull off like Gal.

Colorbond today has a Zincalume base and has the same properties as Zincalume.

As far as corrosion goes you should not run rain water off Zincalume or Colorbond onto a Gal surface as the water coming off is of a pure nature and does not add any protective salts to the water hence will create corrosion to the Gal surface. Whereas water from a Gal roof onto Gal gutter will not create this senario. The reverse is not so which means you can run water from Gal onto Zincalume or Colorbond and it will NOT create corrosion.

The result is the same if running rain water off a Terracotta tile roof it also will create corrosion in Gal gutter. If you want to see this effect have a look inside some old Gal gutter with a Terracotta roof and see the rust spots all along the gutter where the water has been dripping out of the valleys of the tiles.

Tameriska is correct in as much that you should not run water off Zincalume or Colorbond into an old Gal tank as it will accelerate the rate of corrosion and shorten the life of the tank.

[Chris Parks]

A bit late in this thread but my experience with plastic guttering was all good. It was on the house for 20 years, installed by me and never leaked, cracked, broke or discoloured and also it was easy to instal. The only issue I can see with it is in bushfires, it will melt when used to hold water. Mine only came off in house renos and I let them instal colourbond as I won't be here long enough to see it rust. I just don't know why every one knocks plastic guttering when they have not used it. A friend of mine has had it on his house a lot longer than 20 years and it is still going strong. This is just my experience for what it is worth.

[tameriska]

Barry, thankyou for explaining that.
I didnt know all the logic behind it, could just remember being told about it years ago.

[damien]

Is it possible to paint the Zincalume guttering?

[Barry_White]

Is it possible to paint the Zincalume guttering?

You sure can paint Zincalume it fact it doesn't even need a primer either. The only thing you need to do is to make sure there is no oil residue left over from the rolling processes.

[damien]

You sure can paint Zincalume it fact it doesn't even need a primer either. The only thing you need to do is to make sure there is no oil residue left over from the rolling processes.

Thanks for that