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Thread ID: 48136	2004-08-15 03:56:00	Off Topic -Difference between galvanised iron & steel roofing?	Laura (43)	Press F1

Post ID	Timestamp	Content	User
261836	2004-08-15 03:56:00	My family house was built as an 1890s cottage, then got add-ons later (e.g front verandah covered in, bathroom & back porch added) There were also major interior changes in the 1930s/40s. Although I know rough dates for some of these, I've no idea whether the roof is original (in part or whole), merely that it's now a rusty paint-flaking old corrugated iron job which needs attention - and perhaps replacement with a newer product? I wasn't even sure it was galvanised, so tried to find out on the Web what year galvanising became common. The trouble is, references are to galvanised *steel*. Too modern, I guess? As mine is good old *iron*, I need to know the difference in components to make sense of it. Google gives me too much to choose from, so I reckon a Press F1 person ( Any builders out there?) can probably enlighten me sooner... And if anyone has any tips on how to decide whether it's better to patch up or replace an old roof, I'd be grateful.	Laura (43)
261837	2004-08-15 04:14:00	Galvanised Iron and Galavanised Steel are one and the same. The iron bit is traditional usage but is a misnomer, roll formed roofing has always been steel. Without seeing the roof I would be loathe to advise you re replace or patch, can you post a couple of photo's? The other questions I would ask is, what you intend to do with the property, will you get good usage from your investment in a new roof? Your in a rural area aren't you, if near the sea or an industrial zone you will need to get the appropriate corrosion grade to take this into account. Cheers Murray P	Murray P (44)
261838	2004-08-15 04:16:00	"Corrugated Iron" is "Galvanised Iron" is "Galvanised Steel". :D Wrought Iron gates are usually arc welded mild steel. ;-) People use terms wrongly. The difference between your 1890's roofing, and modern roofing is that yours is better. It's lasted that long. The modern rubbish is lucky to beat 10 years. Yours had a heavy coat of zinc, on quite thick steel sheet. Modern stuff is very thin zinc on very light steel. Have a good look at the condition of the steel. It might be still sound ... the paint is the weakest part. If it's not, you might finish up replacing the lot ... you will find that the pitch of the corrugations(distance frompeak-peak) and even the coverage (width) of the sheets is different. I hope that the wood ("rafters, sarking, ...") to which it's nailed is in better condition than mine. :_|	Graham L (2)
261839	2004-08-15 04:45:00	Murray, you're a gem That's what I call a prompt & illuminating reply. So useful to know that our good old corrugated iron is actually steel. It'll make my research so much easier. No pix, sorry. I've not taken any & haven't a digital camera. Actually, I'm not *rural* for this query. This is my Dunedin roof, and as I'm only a few blocks from the harbour (as is most of Dunedin) there are obviously some salt air corrosion problems...which will be ongoing. As for *will I get good usage?*...Depends on how long I live. After 3 generations of my family in this house, I'm not actually planning on selling - despite the real estate agent cards in my letterbox. There's no real panic about the roof. It merely looks dreadful, but amazingly it still doesn't leak. So I have time to work this out slowly... Thanks again. P.S. Concerning my rural *other* address as above - the Central Otago stone cottage of the 1880s does indeed still have its original roof. The paint's peeling, but there's no rust at all. That's the difference between lowland coastal air & the clear dry Central Otago version you get at 1300feet. Horses for courses, indeed...	Laura (43)
261840	2004-08-15 05:00:00	Graham You've encouraged me about my old stuff & demoralised me about the new stuff. (Just read your post after I finished replying to Murray) Mind you, I don't know that my Dunedin roof is an 1890s job. It may have been part of a 1930s/40s tart-up before my knowledge time. Anyway, it'll obviously pay to get someone to do some scratching underneath that thar rust to see how thick the metal is underneath. And yes, Mr Laura has already warned me that replacing *bits* would be hell - as it's old imperial corrugations/sizing & the new stuff is metric, so they wouldn't fit together. Dunno about the rafters/sarking (perhaps just as well?) but I do know the spouting is definitely shot... though trying hard not to notice that yet...	Laura (43)
261841	2004-08-15 05:32:00	Graham's right, the old, thick steel and galvanising they used to use is superior in most respects to the much thinner high tensile stuff they use now but the factory applied coatings are far superior to any on-site applied paint system, there's the tradeoff . Even so, a well installed and cared for pre-coated modern corrugated "iron" roof should perform well for the next generation. Most failures these days are installation error and/or ignorance rather than inferior materials, idiots using pencil to mark, friction blades to cut, wrong fixings, sealants, etc, and leaving swarf and debris on the roof all can greatly reduce the life of the roof. Check your roof space to confirm you have no leaks, delay to repairs can be very costly through hidden decay plus insect attack which can be encouraged by damp conditions (depending on species of beasty). If your not ready for a re-roof, small holes can be patched using a bitumen and aluminium foil composite tape and painted over to match existing. At least fix the guttering as this can lead to water ingress at the eaves or cladding that may not become visible for some time at which point remedial work could be costly. Cheers Murray P	Murray P (44)
261842	2004-08-15 05:41:00	Laura We replaced our roof on an ~1890's house a few years back. I know with some certainty that the roof was original, and it was replaced by us as an part of an overall refurbishment and to accommodate some additions. We used Coloursteel, in the traditional corrogated (but metric?) format, however our architect opted for the heavier guage steel. He would not use the common (26 guage) thickness on any of his buildings and always specified the thicker (22 guage) product. Its as thick as the old stuff, which was very solid (but was rusted quite badly in places). Having seen the product I agree with the architect. But of course we were replacing the entire roof, so matching it was not an issue. Not sure there is much difference in the metric vs imperial though.	godfather (25)
261843	2004-08-15 06:12:00	Thanks, Godfather Your information about Coloursteel was very interesting . I wasn't aware it was available in 2 guages . I've not researched that far yet (still trying to canvas options of repair versus replacement) but have kept that choice at the back of my mind for checking later if necessary . Your additions made it sensible to start from scratch, so you wouldn't have costed out my alternative choices - or perhaps you did? Obviously, that decision comes down to how far gone my roof is -hence an expert opinion from someone who climbs over it, plus a quote - before looking at the Coloursteel prices (presumably found easily on a website?) So I'll remember that the thick version is the way to go . . deciding? Ob	Laura (43)
261844	2004-08-15 06:58:00	Color Steel (TM) or Colorcote (TM) do come in two gauges, as per GF's advice, .55 and .4 (24 and 26 gauge, or thereabouts, respectively). The .4 is paper thin, higher tensile steel, and not used by those with quality in mind IMO. However the grade of coating is more important for durability and has more impact on cost. As a general rule (there are other variables) if your within 500 metres of the sea you will need to use a product with a coating rated for severe marine environments. For quotes and installation, use members of the NZ Roofing Association, make sure they pass on theirs and the manufacturers warranty. GF, some of the old roofs were 22 guage but I don't think they were ever mad enough to use 26 gauge. There were also at least 2 different corrugated profiles. Roll forming was often done locally so profiles often varied from place to place or house to house (from batch to batch) due to wear or mis-adjustment of the machinery (or operator). Cheers Murray P	Murray P (44)
261845	2004-08-15 07:18:00	>f near the sea or an industrial zone you will need to get the appropriate corrosion grade to take this into account. I'm pretty sure that Zincalume ( that spelling may be wrong) coated steel is a better product when near the sea.	mikebartnz (21)
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