Custom orb roof and wall cladding
Roof sheeting - Roof and wall cladding on a sea front house in the highest cyclonic terrain category.  Tremendously strong but still good looking.

Steel roofing

On this roofing page.
Types of sheeting, | Before you get on a roof | Incompatible Materials | Maintenance | Stripable Plastic Coating

What I am going to be talking about here is external fixing of roof sheeting.  Not the secret fixed and crimped or the seamless sheeting.

I will be using the names as used in Australia, but other countries use the same technology with similar profiles.  The photos show fastenings that are for cyclonic areas.  They are typical for other regions, but the spacings could vary.

Corrugated roof sheeting or roofing iron has been around since the 1830's in England.  It was and still is a significant invention.  The simple process or forming corrugations into a flat floppy sheet of thin iron changed roofing for ever.  Because of it's lightness and strength, easy transportability, tons of it was shipped all over the world, including Australia.

Types of Roof Sheeting Available.

Spandek roof sheeting
Spandek roof sheeting
Custom Orb Roof Sheeting
Custom Orb Roof Sheeting
Trimdek sheeting
Trimdek sheeting Roof Sheeting
Klip Lok roof sheeting
Klip-Lok Roof Sheeting

Here, as far as I know the locally produced steel roof sheeting in Australia all comes from the one source, which used to be called BHP but now is using the name BlueScope.  I will be using their names for the material and profiles, but local suppliers use their Types_of_Sheeting_Available.own names for what is the same base material and the same or very similar profiles.

The main product that has replaced the old galvanised iron is called "Zincalume".  This name being derived from the two main components of the actual coating system, which consists of Zinc 55% / aluminium 43% / silicon 1.6% that coat the steel base.

The material is sent from the steel mill in large rolls of flat sheet.  (I'd guess a couple of tonnes per coil).  The main difference in the coil products are:-

  • Zincalume - This is the natural colour of the sheet that looks similar to the old galvanised iron.  It weathers with times and loses it's bright shiny look.  If you are thinking of painting this material, as we did with galv. iron, leave it to weather before painting.
  • Colorbond This is Zincalume with a paint surface added.  It comes in about 20 various colours.  It has a plain pain painted finish to the underside.
  • Colorbond Steellic - A Steellic sheen that changes under different light conditions.
  • Colorbond Ultra - For severe coastal and industrial environments.
  • Stainless - For severe coastal and industrial environments.
  • Thickness - Check out the table below.  For the most part I think that for private house work the 0.42mm thick is the most common.  As you can see it is pretty thin stuff, less than half a millimeter most of it.
  • Galvanised - steel sheeting is still made, but in the thicknesses for roof sheeting it most probably only done as special orders for heritage restoration work.  Where I do see it quite a lot is in the form of valley gutters, in thicker gauges, say 2.0mm.

Various local companies  do the roll forming.  They turn the coils of flat into various standard profiles for which the engineering properties are documented.  There are quite a few roof sheeting profiles available, but the main ones for housing are as follows:-

BMT Width overall Cover width Rib depth Minimum Roof Pitch
Custom Orb
(used roof and walls)
838 762 16 5 deg (1 in 12)
Custom Blue Orb
(for roof pre curving)
838 762 17 5 deg (1 in 12)
(used roof and walls)
816 762 29 2 deg (1 in 30)
754 700 24 3 deg (1 in 20)
Klip-Lok 406
432 406 41 2 deg (1in 30)
1 deg(1in 50)
1 deg (1in 50)
Klip-Lok 700 Hi-Strength
710 700 43 2 deg (1in 30)
1 deg (1in 50)

You can see from this short list, that the shallower the roof sheeting pitch, the deeper the ribs have to be, and also the thicker the material in most cases.
There are a handful of other profiles available that are less common on typical house construction.  Also there are some specific wall cladding options also.

A visit to BlueScope's website will give you heaps of detail.

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Before you get on a roof.

Read the roofing safety page

Get your ladders set up right.  Here's a link to my ladder safety, handling ladders page.

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Maintenance of Sheet steel roofs and walls

Modern Steel roofing if done well will last as long as the rest of the house!  Easily, no sweat!  The manufacturers say that under normal conditions where the roof is washed down with rainwater no maintenance needed.

Read what I said about maintenance on my roof care page.

I advise that you do a bit of preventive maintenance every so often.  Note I am not specifying a time frame here.  Only you can judge your own conditions.

  • Look at the height of you profile, say 16mm for Custom Orb.  It is easy to see that a build up of leaf mould on your  roof could push water sideways and it could be running over the screw seals.
  • Worse than that though, the leaf mould provides ideal conditions for rust to get a hold, and you can't see its happening.
  • If you have Steel clad walls  you should wash them down now and again  under the eaves, or garage doors etc. anywhere that dust and then gritty grime will lodge.
  • Your wall cladding should be at least 150 higher than natural ground level.  ( BCA regs).  Even if we are talking about garages and garden sheds, you must keep the cladding out of the soil.
  • What I see quite often is that some well meaning soul lays a garden bed up against the house and plants some pretty flowers.  Magic!  Apart from possible infestation by vermin, the wall structure and cladding are not designed to be permanently moist.  Don't do it!
  • Every time you think about putting something like a garden bed or a shade house up against the wall, anything not approved, that may hold moisture against the house, ask yourself would you still do it if you knew that in a couple of years time you will have done a few thousand dollars worth of damage.
  • I forget the name of the creeper that I pulled off a wall once, but the whole surface was marred. No real way to fix it , marks etched deeply into the surface.
  • If you notice any unusual stains on roof sheeting or wall sheeting, find out what is happening, where they are coming from.  If you have built onto an existing roof you may be getting problems with incompatible materials.  See below.

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Incompatible Materials

The most common mistake that people make when trying to fix small leaks in their roofs is using the wrong sealants.  Any silicone that says "acidic cure" is not compatible with Zincalume based roof sheeting.  That includes most of the bathroom, glass and wet area stuff.  You must use neutral cure silicone.  It usually says Roof and Gutter etc.

There are a few other materials that are are incompatible with one another, and then there is the problem of galvanic corrosion. Do NOT miss this page if you work on steel roofing.

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Stripable Plastic Coating

Don't fix flashing with it still in place, thinking that it will peel off afterwards.  It does come off, but it is a pain to do it, and there are always dags of plastic around the screw heads.

If you have left overs from a job and think you might find a use for them later, strip off the plastic, or they may be useless in a few months time.  Certainly if left in the sun

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Please Note! The information on this site is offered as a guide only!  When we are talking about areas where building regulations or safety regulations could exist,the information here could be wrong for your area.  It could be out of date!  Regulations breed faster than rabbits!
You must check your own local conditions.
Copyright © Bill Bradley 2007-2012. All rights reserved.
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