A Colorbond roof can last between 50 to 70 years and possibly longer with proper and regular maintenance. This is based on what we’ve observed with the thousands of re-roof jobs we’ve undertaken in South East Queensland and what BlueScope Steel guarantees with their product warranty. Colorbond steel is designed specifically with the Australian environment in mind, which is why it’s the most popular roofing material for both new and existing homes around the country.
However, the real variables are all the things that happen after the sheets leave the factory. How the roof is put on, where it is located, how it is pitched, what colour you chose, and whether or not anyone’s bothered to hose it down in the last ten years. All of this is what’s going to determine if your roof lasts for as long as it can.
If you know your Colorbond roof is getting on in years and would rather talk to someone than read an article, give us a call on 1300 12 ROOF (1300 127 663) for a straight answer on where things stand.
What affects the lifespan of your Colorbond roof
The same raw material underlies all Colorbond roofs, but it’s down to four variables whether your roof lasts until it’s 40 or more than 70 years old. Only one of them is beyond your control.
Installation quality
This is the single biggest factor, and the one most homeowners neglect. A Colorbond sheet is only as good as how it is fixed, overlapped, and flashed. Wrong screw location, under-tightened or over-tightened fasteners, insufficient overlap in sheet joints, and poor flashing around openings are all installation problems that won’t appear in the first year or two, but they do allow moisture to get inside and corrode from the inside out.
Proper installation is done by following BlueScope’s specifications to the letter. Proper installation also involves understanding the interaction of the roof structure underneath the newly installed sheeting, especially for older homes where battens need to be replaced or adjusted. We will discuss this further down, as proper installation is more than just worth mentioning. Learn more about A.M.J’s approach to Colorbond roofing in Brisbane.
Environmental conditions and location
A roof on a property in Kenmore, in suburban Queensland, is subjected to vastly different conditions to one in Burleigh Heads or one out at Toowoomba. The salt air is the strongest environmental factor for any roof in coastal areas. BlueScope takes this into consideration with specific product recommendations depending on distance from the coast, but even with the correct product, the roof will be working harder if it is in the Burleigh Heads area than one 30 kilometres out.
Humidity and storm frequency are factors, too, along with airborne debris and salt carried in the wind. Properties with heavy tree canopy cover will experience issues with leaf litter and moisture accumulation in valleys and gutters, which can cause corrosion if poor drainage is allowed to occur. Hail is also a factor in some areas of South East Queensland, particularly along the corridor. Although Colorbond steel handles hail well, extreme events will cause denting, compromising the finish of the coating.
Roof pitch and drainage design
Roof pitch has a direct influence on the speed at which water drains off the roof surface. This implies that a steeper roof allows water to drain off fast, limiting the moisture retention on the steel material and the potential for corrosion on the overlap and screw areas. On the other hand, a low-pitched roof retains water longer and has a high potential for the accumulation of debris in the valleys.
BlueScope provides minimum pitch recommendations for various Colorbond steel profile types. While going below these minimums is a non-compliance problem in itself, even going with the minimums does not always guarantee the best possible drainage. Drainage is further affected by the gutter and downpipe sizes and the positioning of valleys and the presence of overflow points. If a roof is designed with inadequate fall and gutter sizes, the water ponds on the roof during heavy rain and sits on the flashings and lap joints. This can cause problems after 20 or 30 years.
Colour selection and UV exposure
This is one factor that, again, no homeowner typically thinks about when deciding their Colorbond colour, but it will have a real-world effect in the long term. It’s no secret that darker colorbond materials will absorb more heat than lighter colorbond materials. On a 35-degree day in Brisbane, a Colorbond roof in Monument or Night Sky will likely be above 70 degrees, whereas a Surfmist or Shale Grey Colorbond will be 20-30 degrees cooler.
This sustained heat cycling does two things. One: it hastens the natural degradation of the paint system. While BlueScope’s baked-on paint finish is designed to withstand UV and heat, darker colours work the paint harder because they absorb more of the sun’s heat rather than reflecting it. Over a period of 25 to 30 years, you’ll see more paint chalking and colour shift on a dark roof than a light roof in the same suburb.
Two: the process of expansion and contraction due to heat is more pronounced in darker colours. Metals expand when they are heated and contract when they are cooled. On a daily basis, the range of expansion of a dark roof will be greater than that of a light roof. Over thousands of cycles, the stress on the fixings will be greater.
In all our projects, the result is the same. Colours that are lighter will last longer. This does not mean that if you prefer a darker colour, you should not use it if it is suitable for the exterior of your home. However, it is important to note that your Monument roof will require more maintenance after year 25 than your neighbour’s Surfmist roof. While the visual attractiveness of a darker roof is important, it is also important to note that you need to go into the decision with realistic expectations. If you are trying to decide on the merits of Colorbond compared to other materials, our guide on Colorbond roofing vs tile roofing discusses the merits of each on durability.
How Brisbane’s climate specifically impacts Colorbond roofs
Most articles that discuss the longevity of Colorbond roofing mention “harsh Australian weather conditions,” but this is a broad brushstroke, and the fact is, Australia does not have a uniform climate. It does vary, and this is important to know if you are concerned with the longevity of your roof.
The South East Queensland environment offers a mix to your roof that is unique compared to a Colorbond roof that is exposed to a Melbourne or Perth environment. The humidity is constant from November to March. The constant moisture in the atmosphere, coupled with warm weather, means that if there is any weakness in the roof’s protective system, it is exploited much faster than if the roof was exposed to a dry environment. A scratch on a panel or a faulty screw washer that may take 15 years to become an issue in Adelaide may become a corrosion issue on a roof in Brisbane within 5 to 8 years.
Then, of course, there is the storm season. SEQ is often battered by severe weather conditions between October and April, with hail and driving rain, as well as wind gusts that test every securing point on the roof. Properties along the western corridor from Ipswich through to the Lockyer Valley are often worst affected by hail, while the northern suburbs and the Moreton Bay region are worst affected by wind-driven rain coming off the coast. The damage caused by severe weather is not always immediately visible from the ground. Hail, for example, causes tiny dents in the paintwork, and these eventually develop pinpoint corrosion areas that are only visible years later.
Properties in coastal areas such as the Gold Coast and Sunshine Coast have to contend with salty air, which hastens corrosion on exposed metals. BlueScope’s product selection guide indicates different Colorbond products based on how close they are to the ocean, with the best corrosion protection offered within 500 metres of breaking surf. However, even inland properties can be exposed to salty air during onshore wind events. We have seen roofs in Mermaid Waters and Caloundra that have weathered differently to the same products installed at the same time in an inland area, simply due to cumulative salt exposure.
The intensity of the UV rays in Queensland is yet another factor that is always at work. Brisbane is said to have some of the highest UV index readings in the country. The constant bombardment of the UV rays is what causes the gradual chalking of the paint, which is normal on any Colorbond roof, although the rate is faster in Queensland than in the southern states.
However, Colorbond is still the appropriate material for roofing in Brisbane, as it performs much better under such conditions compared to concrete or asphalt shingles. This is just one example of why product suitability and quality are important.
What the BlueScope Steel warranty actually covers
BlueScope offers a manufacturer’s warranty on Colorbond products, which covers the steel and the paint finish. However, the warranty on the steel and the paint are two separate warranties with different terms and conditions.
The warranty for steel and coating covers perforation due to corrosion, and this lasts from 10 years for standard Colorbond Ultra to 25 years or more for their higher-rated coastal products, depending on your location relative to the coast. The paint finish warranty covers peeling, flaking, and severe colour fade outside specified colour ranges. This is normally less than the steel warranty and lasts around 15 years, depending on the product and colour.
However, there are conditions. First, the roof has to be installed based on BlueScope specifications, and proper materials have to be used depending on the location, especially if it’s a coastal location. Second, the roof has to be properly maintained. This means if the roof has not been cleaned in 20 years and has leaf litter accumulating in the valleys, then it has not been maintained properly.
The warranty provided is also a manufacturer’s warranty, not an installation warranty. It covers any defects in the Colorbond material itself. If your roof fails due to installation problems, such as using the wrong type of screw, insufficient overlap, or improper flashing, that is not BlueScope’s problem. That is your installer’s problem. This is why we also offer a 10-year written workmanship warranty for our installation service from A.M.J.
One thing worth noting: The warranty only covers where the property was when we installed it. If, according to our corrosion mapping, your address needs a certain product grade, and your installer has used a lower-grade product to save money, forget it. It’s just one more reason why we advise users to use an installer who is a BlueScope Industry Partner and follows our product selection guidelines.
When a Colorbond roof starts showing its age
Colorbond does not fail suddenly catastrophically, but rather ages over time, and understanding that means you can pick up on any issues while they are still minor, rather than when water starts leaking through the ceiling.
The first indication of this process is normally the chalking of the paint. To test the surface of a panel of paint, run a finger along the surface and see if there is a residue left behind. Some paint chalking after 15-20 years is completely normal and should not be cause for replacing the roof. It is a cosmetic change and not a structural change. However, when the chalking is significant, and the original colour of the paint has faded significantly, and the surface of the paint is rough to the touch, then the paint is no longer functioning at its full potential.
However, paint flaking is more concerning. While chalking is simply a gradual degradation of the paint’s surface, paint flaking is where actual portions of the paint film are lifting away from the steel substrate. Once this occurs, moisture is introduced to the base metal, and corrosion begins. If you see this on multiple panels, it means your roof is at a point where discussions about restoration or replacement begin.
Screw fasteners are the most common point of failure on an otherwise sound Colorbond roof. The neoprene washers under the screw head are what make a watertight seal, and they deteriorate much quicker than the steel itself. After 15 to 25 years, they harden, crack, and lose their seal. This means water leaks down the shaft and into the timber batten or purlin below. You won’t be able to see this from outside your building. The first sign of this problem might be a small rust mark around a screw head, or worse, a damp patch on your ceiling inside. If you’re experiencing these kinds of problems, it might be time to think about your options for getting your metal roof fixed.
Another aspect to monitor is flashing deterioration. Flashings are the metal pieces used to cover the joints at roof penetrations, ridges, valleys, hips, and intersections with the wall. Flashings are dependent on the effectiveness of the sealant and the overlapping of the flashing. The sealant will deteriorate over time, and if the flashing was originally poorly done, it will lift and separate due to the expansion and contraction of the roof. The flashing at the valley is the most critical part of the roof, as it carries the most rainwater.
Corrosion of the gutter and downpipes is often a problem before the roof itself begins to deteriorate. Gutters are designed to hold standing water, debris, and other matter that is carried through the air. This accelerates corrosion, even on new roofing materials. If your gutters are suffering corrosion, then it may be a good time to have the roof inspected, too.
If you can spot two or more of these signs, your roof is not necessarily done, but it’s telling you something. A professional assessment will determine whether you are looking at targeted repairs, a screw and washer replacement, or whether it’s time to start thinking about a new roof. Our guide to signs your home needs a roof replacement covers all of this in more detail.
Maintenance that extends your roof’s life
One of the advantages of Colorbond roofing is that it requires minimal maintenance compared to other types of roofing materials. However, minimal does not mean zero, and a Colorbond roof that lasts 45 years compared to one that lasts 65+ years can often come down to a few maintenance practices.
How to clean a Colorbond roof safely
Periodic cleaning is the maintenance activity with the greatest impact. Eventually, dirt, airborne contaminants, pollen, and other organic materials accumulate on the surface. Under the humid conditions of Brisbane, these contaminants have the potential to trap moisture on the surface, leading to the possibility of mould growth.
BlueScope suggests that the roof should be washed using clean and fresh water, and if necessary, a detergent solution. The garden hose from ground level is sufficient for cleaning the roof. If you can reach the roof, or hire someone to do the job, a soft broom and hose will clean the grime effectively.
High-pressure washers should not be used directly on the panels, as this will damage the paint system and force water into overlap joints and under flashings. Bleach-based cleaners and abrasive pads should also be avoided, as the harsh chemical solution will damage the protective coatings.
For most properties, cleaning once a year is all that’s needed. Properties under tree cover or near the coast might even consider cleaning twice a year. It takes a couple of hours, tops, and it is the cheapest thing you can do to protect your roof.
Gutters, downpipes and drainage
A clean roof with gutters clogged still remains at risk. If gutters become clogged with leaves, water will back up and settle at the bottom edge of the roofing sheets. Eventually, this water will penetrate under the sheeting through capillary action, especially at the fascia line. This leads to corrosion at the edge of the roof where sheets are cut and where the steel core is exposed.
Gutters should be maintained by cleaning out the debris at least twice a year, especially if you have tree branches hanging over the roof. Make sure the downpipes are free flowing and clear of blockages. If a downpipe is only partially blocked, it affects the entire gutter system and causes areas of overflow. While you are cleaning the gutters, check the gutter brackets and make sure nothing has sagged or separated from the fascia.
Inspections after severe weather
During the storm season in Queensland, a storm can produce hail and heavy rain, as well as strong gusts of wind, with little warning. After a strong storm, it is a good idea to have a professional check your roof, even if you cannot see obvious signs of damage from the ground.
Hail damage to colorbond roofs is not necessarily dramatic. There may not be holes or major dents. What hail damage will commonly cause, though, is impressions in the metal, and those impressions will crack the paint film where the hail stone made contact. Each one of those cracks has the potential to be a corrosion initiation site. On a roof, there will be many, many impressions after a hail event, and after several years, the damage can be considerable.
Wind damage can also cause screw fixings to loosen and lift the flashings. Moreover, it can also displace the panels at the overlap. Once again, this will not be visible from the ground. A competent roofer will check the fixings, flashings, and overlap of the roof panels to ensure that there are no problems. You can also book a roof inspection in Brisbane after the storm.
A.M.J handles a large volume of insurance-related roof work following a big storm in SEQ. If your roof has been damaged in a storm, we recommend that you lodge an insurance claim promptly. We deal with all major insurance companies and can assess your damage and obtain a detailed report for you. We then take care of the repair/replacement process from there. Learn more about our storm damage and insurance repair services.
Ventilation and condensation prevention
This is a maintenance factor that most people don’t even think about, but rest assured, this is one area that directly affects the underside of your Colorbond roof. In a poorly ventilated roof space, warm, moist air rises up through the living areas below and condenses on the underside of the cool metal sheets. This condensation can actually corrode the roof from the inside, somewhere you will never even think to look until the problem is serious.
Proper roof ventilation ensures the free flow of air through the roof space, removing moisture before it condenses. Whirlybirds and ridge vents are the most common roof ventilation methods, although eave vents can also be used in certain roof designs.
If the roof space appears humid when you place your head through the manhole, or you see moisture droplets on the roof’s underside, then you need to improve the roof’s ventilation system. This is a relatively inexpensive process that ensures the roof’s thermal efficiency and integrity are maintained in the long run. It also saves you on cooling costs during summer by preventing the roof space from accumulating heat. Discover more about roof ventilation systems and how they can improve the lifespan of the roof.
Why installation matters more than the material itself
You can have the best Colorbond product that BlueScope makes, but if it’s installed badly, it’ll be gone in half a century before it’s even close to being due for replacement. That’s not an opinion. That’s what we see over and over again when we remove old roofs and try to work out what went wrong.
The most common error we find in installations is the type and position of screws. The Colorbond profiles use particular types of screws with particular washers, screwed into a particular torque. If the screws are over-driven, the washer gets compressed too much and fails prematurely. If screws are under-driven, they don’t seal properly from day one. If screws are placed in the wrong position on the ribbed profile, they don’t capture the batten underneath, or they sit in a position where water collects around the fixing.
Flashing work is where the quality of installation really differentiates between experienced metal roofing specialists and general builders or handyman types. Flashing over penetrations, valleys, where roof planes meet walls, and at ridge lines are areas where water entry can occur on any roof. Getting a flashing right involves an understanding of how water behaves on this particular roof under conditions of heavy rain. Bending a piece of metal to a vaguely correct shape and siliconing the edges is not enough.
We have had to replace roofs that are only 15 to 20 years old because the original installation was done so poorly that the Colorbond, which is supposed to last another 30 to 40 years, is corroding on every fixing point and every lap. The material is great, but the installation ruined it.
Overlap and lap joint sealing is another area where shortcuts result in failures. Overlap areas have a minimum overlap distance depending on the pitch of the roof. Cutting down on overlap means water seeps up through the overlap by capillary action, and this is a certainty on a low-pitched roof during a heavy rainstorm. The corrosion occurs hidden from view, and problems are seen when it eats its way through from the inside.
This is why A.M.J offers a 10-year written workmanship warranty in addition to the manufacturer’s BlueScope warranty. While the material warranty protects the steel from defects, the workmanship warranty protects the installation of the steel. This is because we are confident that the difference between a Colorbond roof lasting 30 years and one lasting 60+ is the quality of the installation. With 7,000+ re-roof projects undertaken in South East Queensland, we’ve developed a system to get the details right on every job, whether it’s a residential or commercial property.
What should a homeowner look out for in terms of quality? The screw lines should be along the battens precisely, with no wandering lines. The flashings should be lying flat against the surface, no gaps, no edges lifted. Check out the overlapping lines, too. If you see sealant squeezed out the sides, that means the overlaps weren’t done well. The caps should be straight and evenly fixed. If you see daylight under a flashing, or if you see screws sitting at funny angles, that means the quality of installation was not what it should have been. If you are worried about the state of your current roof, knowing about replacement costs will help you work out whether repair or replacement would be more cost-effective.
Talk to a metal roofing specialist about your roof
The best thing you can do for an aging Colorbond roof is to get a professional opinion from a person whose business is dealing with metal roofs every day.
At A.M.J Metal Roofing, we have been re-roofing homes and businesses in Brisbane, the Gold Coast, Sunshine Coast, Ipswich, and Toowoomba since 2010 and have a combined 50 years of experience. We will assess your current roof and provide an honest opinion about the state of the roof. After that, we will discuss our options with you without any pressure. If the roof does not need to be replaced, we will also tell you that.
Call us on 1300 12 ROOF (1300 127 663) or fill out our online form to have one of our team members on your roof within the week.
FAQs
Can a Colorbond roof last 100 years?
Yes, it’s theoretically possible for a Colorbond roof to last for 100 years. However, no Colorbond roof has yet been around for this length of time because this technology has not been around for this length of time. Based on accelerated testing done by BlueScope, and what we can see on roofs installed in the 1960s and 70s using an older version of this technology, it’s likely that a well-maintained Colorbond roof will last for between 50 and 70 years.
Can this best-case scenario be extended further? Who knows? But it would be optimistic to expect a roof to last for 100 years.
How often should I have my Colorbond roof inspected?
It’s a good idea to get a professional inspection of a Colorbond roof every two to five years on most Brisbane homes. If you’ve experienced severe weather, especially hail or strong winds, it’s a good idea to get the roof inspected regardless of the time of year. Coastal areas and areas with a lot of tree cover should get more frequent inspections than this. An occasional visual inspection from the ground with a pair of binoculars can help you spot obvious problems with the roof.
Does the colour of my Colorbond roof affect how long it lasts?
Yes, to a certain extent. Dark colours absorb a lot of heat, and this speeds up the aging process of the paint system and also increases stress on fasteners due to expansion and contraction. Colours such as Surfmist and Shale Grey age slower than darker colours like Monument and Night Sky when subjected to similar conditions. This difference won’t be dramatic in the first 15 to 20 years, but after 25 years, it will become more pronounced. This also has a bearing on how much one spends on cooling, as lighter colours reflect more heat away from the house.
Can a damaged Colorbond roof be restored instead of replaced?
This is dependent on how extensive the damage is. If it’s only minor issues like corroded screws or areas where paint is peeling, it can be repaired. The same applies if some of the flashings have been damaged. Roof restoration is possible, but recoating a roof is not always the best option in terms of cost, especially if the roof’s steel is compromised. We will determine whether your roof can be repaired or restored, giving you an honest opinion on whether it’s worth it, or whether it would be more beneficial for you to replace it entirely. If it would cost more than 40 to 50 per cent of a new roof to make repairs, it would be more cost-effective to replace it entirely. For more information on what factors go into this, you can refer to our guide on roof restoration costs.
Is Colorbond roofing suitable for coastal properties in Queensland?
Yes, it is suitable, and the appropriate product must be specified. BlueScope produces Colorbond Ultra, which is suitable for coastal and severe coastal areas. This product selection is based on the distance of the property from the breaking surf and the prevailing winds. If you are within 200- 500 metres of the coastline, the highest-rated product is recommended (standard Colorbond can be used, but Ultra offers higher performance and better warranty protection in this range). Further back, standard Colorbond with proper maintenance is generally satisfactory. A.M.J installs Colorbond roofing on coastal properties on the Gold Coast and Sunshine Coast regularly and specifies the appropriate product selection based on BlueScope’s corrosion mapping. Using the wrong product grade on a coastal property is one of the quickest ways to void your warranty and minimise the lifespan of the roof.
