roof life

I was just in the roof space (before the heat) and noticed that up at the apex the corrogated sheeting (colorbond custom orb) the edges of undersides down for about 50mm, are starting to show signs of rust & white powder?

what service life is normally expected from this type roof? I know the house was built in 77, so already the roof is approx 28 years old.

I was thinking of wire brushing the apparent corrosion then spraying with a zinc rick paint. Is there anything else I could do?

Looking forward to any suggestions or comments. Thanks

On the Lysaght web site I just found tech bulletin No 2 which tells me how to paint existing product. (should've look there first) I'm still posting this thread as it might interest someone else.

http://www.bluescopesteel.com.au/au/...F017632B735E39

I know that life of roofing is subject to the conditions prevailing but it would be intersting to have comments from others.

look forward to your response

John

Wouldn't be dead for quids

John

How far from the ocean are you as this will have a direct bearing on the life of the roofing material. If you get wind driven salt laden air it will get up under the ridge cap and will not get regularly washed by the rain.

Another problem is if the top of the sheets where cut with a abrasive disk it opens up the bare metal, whereas if the sheets are guillotined as in when they are cut in the factory the shearing action draws coating over the bare cut edge.

If you are within 100 metres of the ocean Bluscope Steel® recommends Stainless Steel Colorbond®. If you are within about 500metres of the ocean they recommend Ultra Colorbond®.

Even so at 28 years you would be outside their 25 year warranty period but if I was you I would still approach them you never know they may replace it but you would have to be outside those distances I quoted above.

Back at that time some of the earlier Colorbond® was actually put onto galvanised sheet rather than Zincalume® and this would certainly have shortened the life of the sheet.

The fact that you say that it is showing a white powder tends to make me believe it could be galvanised sheet.

The only other problem was back then also some of the other roof suppliers like Monier and Hunter Douglas at the time were importing coloured roofing from New Zealand and Bluescope would not cover them under warranty.

Bluescope can actually test the steel and tell you if it is theirs.

I was a rep for Lysaght BHP Bluescope for eleven years.

Just as another point to really protect it from going further you would have to remove the ridge cap and treat the top side as well.

thanks Bazza for the info.

The house is 6-7 Kms from the port of Cairnsand probably 3-4 ks to the nearest tidal creek, so certainly not in the danger zone and there is definitely no breaking surf nearby in this part of the world.

I'll have to get a step ladder in the roof space to determine if the edges were cut with a disc or not.

this started me looking at the rest of the roof, and i see that some of the cyclone clips under the roofing screws have started to corrode. only slight alpha rust at the moment no thick flaking beta rust causing any break down so the clips look okay I'll probably apply the same zinc rick paint before applying a coating over the whole roof.

I'll get on to Lysaght on Monday to check next steps

thanks again Bazza for your time.

cheers