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

Roof Sheeting or Cladding, Corrugated Iron or Metal Roofing.

Metal roof sheeting is an old material, ( in Australian terms).  It has been made here for about a century and although it has had it's ups and downs in terms of popularity it has always been the best roofing material for many people.  Myself included.  I am biased.

I built my first house with a Monier cement tile roof coated a rich red terracotta colour.  It looked great, but it was as hot as hell.  Those tiles soaked up the heat during the day and kept it most of the night.

Metal roof sheeting is cheap to buy, quick to fix and easy to maintain and repair.  It also has excellent thermal and so energy efficient characteristics.  It is can be used in the most severe weather conditions.  The roof above is right on the coast in Darwin and as such can be expected to survive severe tropical cyclones.  (I did say I was biased).

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.

Roof sheeting - Definitely not a thing of beauty, this original corrugated iron outstation homestead is still capable of doing the job after over seventy years.

Corrugated iron become part of the Australian landscape, from outback stations and water tanks, to ultra modern roofing on sports stadiums.

It's very unique properties helped to develop Australia a century ago, and it is still helping developing countries today.

What other material can you transport with a motorbike, enough roof sheeting for a whole house?

Roof sheeting - Roof sheeting - ready for delivery.  Corrugated sheeting produced from a small shed in Northern Cambodia - 2005. The lengths of the sheets here suit the available transport.

Types of Roof Sheeting Available.

Spandek roof sheeting

Custom Orb Roof Sheeting

Trimdek sheeting 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 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 Metallic - A metallic 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:-

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.

• Don't go on a roof if you are not comfortable doing it. If you are unwell for whatever reason, keep off the roof for the day.  Don't let mates push you into doing something you are not happy with.
• Read and understand all the safety regulations applicable to your area. Over a certain height you may need edge protection, you may have to fix safety mesh, wear personal harnesses etc.
• Over a certain pitch you may lose grip and start to slide,(Yeah I know I am beginning to sound like the warning labels on step ladders "Standing on or above this tread may cause you to lose your balance", but I have to cover my back).
• Wear good gripping shoes or boots.  I used to leave the safety boots off and wear runners or Dunlop Volleys.
• Some weather conditions make the roof slippier than others.  Don't carry mud and crap off the ground onto the roof, wipe your feet at the bottom.
• Dragging power cords over sharp edges of roofing iron is always risky, try not to do it, but ALWAYS use a safety box.
• Watch out for overhead electrical feeds into the house.  Look for power lines outside the block if you are loading up the roof with a crane.
• Get your ladders set up right.  Here's a link to my ladder safety, handling ladders page.
• Wear leather gloves when carrying the sheets and passing them up onto the roof.

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Maintenance of Sheet steel roofs and walls

Modern metal 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 main roof 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 metal 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.

A better alternative to silicone especially for repairing leaky spots that are subject to a lot of thermal expansion are the PU (polyurethane) mastics.  Sikaflex is one of the best.

There are other incompatible materials that are less well known

• Lead. There are still an awful lot of lead flashings out there.  Say you have an existing lead flashing chased into a masonry wall and you want to still use it in a re roofing job.  Put a layer of something between the lead and the metal sheeting or flashing.  Paint, bitumen, roof felt, plastic etc.  Don't let the lead contact the sheeting. 
• Copper.  An old solar hot water tank can leak and leach copper onto the surface.  Fix it.    Copper pipes penetrations should not touch the sheeting.  They should have seals around them.
• Stainless steel (unless of course your roof sheeting is stainless, it is available).  that means no stainless pop rivets or screws.  Same for Monel metal.  It is easy to get your rivets mixed up.  Decktite fittings have stainless steel collars, with a EPDM seal under them.  OK so far, but don't use SS screws, use standard roof screws with EPDM washers to fix them.  (EPDM = ethylene propylene diene monomer).
• Carbon. Would you believe it?  Ordinary pencils are not compatible with Zincalume.  I like using water based kids marking pens.  
• Anything that stops the normal drying out of the roof after rain.  We have already said leaf mold, but what about this.  I once had to replace a section roof because the owner had put a black poly blanket type water heater thing for a backyard spa on his roof.  It sweating away happily for a few years until the inevitable happened.
• Chlorine While on the subject of spas, if you store your pool chlorine in an enclosed steel garden shed, sooner or later the shed will be knackered. More likely sooner if you leave the lids off the chlorine.
• Pesticides Still with chemicals.  On wall cladding watch that you don't get any over spray of pesticide onto the sheeting.
• Touch up paint.  Not really incompatible, but in the past people would buy packs of touch up spray, and spray fist sized patches everywhere there was a scratch.  The end result was that after a couple of years or so the touch up paint would fade and the whole thing looked like a mangy dog.  The current  wisdom is don't paint small marks, they won't cause rust.  For larger damaged areas, change the sheet.  In other words, be careful when you are fixing and you will get a better job.
• But wait......... there's more.  This one for the first time on the web.   Do a google on "Bat shit corrosion" .  only one eh!  You saw it here first.  Anybody who has lived in areas where fruit bats (flying foxes) abound has found out the corrosive power of their crap.  If left on a car for a few days, there will be a permanent mark in the paintwork.  The main reason for buying carports where I live is not weather protection for the vehicle, but to save the time and effort spent cleaning the crap off.  Same thing on roofs.  Now I have no answer to the "in flight" bombers.  But if you are like me and have a nice shady fig tree near one corner of your house that at certain times of the year, the fruit bats during the night and the Torres Straight Pigeons during the day, congregate in for a feed.  then I suggest you time your maintenance to this annual event and cut back the overhanging branches before the tree starts fruiting.

Strippable 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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