In Australia, roofing materials for your new home usually fall into one of two possibilities: concrete roof tiles; or corrugated metal roofing with a bonded paint finish (known in Australia as Colorbond or CB). Which option is best for your situation? Both will keep the weather out, so weigh up a few other factors against your taste, needs, and budget.
A Bit of History: The concept of bonding paint to a galvanized base originated in Chicago, and was brought back to Australia. Here it was further developed into a product that has remarkable corrosion resistance and is aesthetically interesting: Colorbond© . It comes in many standard colours and is resistant to the elements. Whereas in the past a galvanized corrugated roof might have a life 20 years or so, a Colorbond roof would have a 50 year life or longer.
Terra cotta tiles are an option; they are the best form of tile you can have as they literally last forever. There are examples of terracotta roofing that have been around for 1000s of years. Think archaeological dig. However it is significantly more expensive, about double the price of a concrete roof tile.
For our purposes, we will compare concrete roof tiles and Colorbond roofing. If we look at both products for what they’re designed for (keeping the weather out), both do an admirable job. Concrete roof tiles have been used in Melbourne for at least 75 years and there are many houses in older suburbs such as Heidelberg, Camberwell and Hawthorn that still have their original concrete tiled roof.
Why would you select one product over another? It comes down to personal taste, lifestyle, a few other factors… and COST.
Architectural Merit: Architectural merit is a personal matter. What do you like? That’s something that can’t be argued. Colorbond has a modern stylish look with clean lines. However, you should be aware there are many concrete roof tile profiles that give an altogether different architectural result than a standard half-pipe tile. For a small addition in price, you could (for instance) select a flat shingle style that will deliver a very different look. There are also myriad colours in concrete roof tiles.
Noise: This is an important consideration for some people. Insulation and ceiling notwithstanding, you will hear rain on a Colorbond roof. While we might think of raindrops falling on a metal roof as a pleasant sound, it can be disturbing and annoying to some people, especially in heavy downpours. Tile roofs are much quieter.
Water Collection: If you want to collect roof water in a tank for household use, Colorbond is the best option. You will harvest a lot more water than a concrete tile roof because concrete tiles have a level of absorbency. Also they tend to retain dirt, dust and so forth which is then washed off into water tank.
During the most recent 10 year drought in Melbourne, home owners were encouraged to collect rain water for gardens and other household use. The demand for Colorbond roofing was influenced by this.
Weight: Colorbond has a distinct advantage in that it’s light weight so the roof loading is a fraction of the weight of a concrete tile roof (10% of the weight to be precise!) As a consequence, your roof framing is much lighter; rafter spacings can be greater. Also, a Colorbond roof is no heavier wet than dry. A concrete tile roof will absorb a percentage of water before it runs off, so a wet tile roof is heavier. All engineering specifications need to take that into consideration.
Rodents: It is simpler to make a Colorbond roof pest-proof than a tile roof by nature of the way the product is installed.
Bushfire: Melbourne is a city adversely affected by summer bushfires. If you are living in the outlying fire-prone areas, BAL (Bushfire Attack Level) regulations will make it in your interest to choose a Colorbond roof, as they are easier to seal against external ember attack.
Resilience: Colorbond is more resilient than concrete roof tiles. If you need people to climb on your roof for any maintenance reasons, they need to be a lot more careful on tile than on Colorbond. However, if you need to penetrate the roof (for instance for a vent or flue or air conditioning) this will be more expensive with CB.
Eaves or Veranda. If you have an architectural design with extensive verandas or eaves, a Colorbond roof will be more desirable because of its lighter weight. With verandas you want a shallower roof pitch, because the further out you go the lower the head height. To maintain height for a wide veranda, this can only be achieved by CB or some other form of sheet roofing. Typically roof tiles are not recommended on a roof pitch of less than 20 degrees. And because Colorbond is a descendant of old-fashioned corrugated steel, this delivers the traditional Australian veranda look.
Cost: Ultimately, this is the foremost reason for choosing a concrete tile roof. Concrete tiles are over 20% cheaper than Colorbond, so if you have a tight budget I would obviously recommend tiles. This is why more than 90% of homes built in Melbourne have a concrete tile roof. The advertising might have you think that CB is as cheap or even cheaper than tiles, but this is simply not the case.
Designers sometimes prefer Colorbond in a never-mind-the-cost sort of way. I had one client who had paid to have plans drawn up by a designer. When they presented these plans to me for a quote, they were horrified to see 3.5 thousand dollars extra for a Colorbond roof, when they actually preferred a traditional tile roof.
Which roof is best for you? Look at each factor above as it relates to your situation. Weigh up its degree of importance, and then decide which roofing material best serves your particular needs, tastes, and lifestyle.
Do you value integrity, communication and superb quality throughout the building process? Do you have a question about your block or dream home? John Kearney is a Melbourne Building Design and Construction Consultant who has been in the building industry for over 20 years. He is passionate about giving people a cost effective alternative to building in the areas they love, and specialises in solutions for difficult and sloping blocks. Find out more at http://slopingblocksolutions.com.au/ Tweet with John at SBSBuilder and Like his Facebook page to get tips, updates and a bit of humour!