Decramastic Roofing: What Homeowners Should Know, and Why It May Be Time for a Replacement

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Decramastic roof tiles, also known as pressed metal tiles or “Decrabond”, were a popular style of Australian roofing during the 70s, 80s, and 90s. Decramastic roof tiles did not require removing the original corrugated roof to install and were simply layered over the original structure. Because of this, they provided a convenient form of roof renovation that could be used in place of a complete roof replacement.

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After

While such methods of ad-hoc construction have long been discontinued, many homes in South Australia still sport this problematic style of roofing. In this blog post, we will explore the pros and cons of decramastic roofing and explain why homeowners should consider retiring their metal roof tiles in exchange for a modern and long-lasting solution.

Above: 1980s Decramastic metal roof tile cladding over the top of original 1920s corrugated iron.

What is a decramastic roof?

A decramastic roof consists of pressed metal tiles that are typically manufactured from aluminium and steel. Some decramastic roof tiles were even finished with a sandy, grit-bonded texture, which, at a glance, gave them the appearance of concrete tiles.

By the 1970s and 1980s, early 20th-century houses that were originally built with corrugated iron roofs were around 50 years old, and their original roofing was past its serviceable life. As a result of its overwhelming popularity, decramastic roofing was used as an alternative to complete roof replacements on these older properties.

Above: A decramastic metal tiled roof part way through replacement. Note the grit bonded surface of the aluminium tile.

How was decramastic roofing installed?

Installing decramastic roofing relied on fixing timber battens directly to the original corrugated iron roof. Tiles would then be laid on top of these battens. This was a relatively unobtrusive method of installing a new roof that reduced the risk of water ingress. Unfortunately for uninformed homeowners, the cons of this technique far outweighed its pros.

The performance of the new decramastic roof was, and is to this day, terrible. Roofs clad with decramastic tiles are effectively non-trafficable. This means that anyone weighing more than a 10-year-old child would leave severe damage and dents if accessing the roof. Once dented, the thin and lightweight tiles could be quickly blown off even by moderate winds.

Above: Metal roof tiles partially removed, revealing original 95 year old corrugated iron roof below and timber battens and frame work.

Can a decramastic roof be painted?

Another drawback of decramastic roof tiles is that they cannot be painted or restored. While it is theoretically possible to apply a new coat of paint to the surface of the tiles, other practical problems make it an infeasible solution. The biggest obstacle to any form of roof painting and repair effort is the trafficability of the decramastic roof. Due to the fragility of their tiles, decramastic roofs sustain significant damage during the painting process. This is just one of the many reasons why decramastic roofs are being replaced rather than restored or painted.

Above: All metal roof tiles now removed from this area. Roof partially re-clad with new Colorbond sheeting with insulation blanket below.

How are decramastic roofs replaced?

The process of replacing a decramastic roof consists of several stages. As the vast majority of decramastic roofs are installed over an original roof, two roofs must be removed before re-installation can begin.

The first step is removing the decramastic tiles, which are incredibly light, especially when formed from aluminium. Because these tiles are usually made in strips 2 – 4 tiles wide, they can be easily ripped from their respective battens. The metal tiles are then thrown into a large skip for removal as recyclable scrap metal. After the tiles are successfully detached, the battens and timbers follow suit. Finally, the contractor can remove the nails on the original iron roof and dispose of the corrugated iron sheets.

With both roof claddings now safely removed, the re-installation of a new Colorbond roof can begin. This process starts with checking all the structural timber members for rot and termite damage, then re-fixing the original roof purlins. The final stage of the roof replacement process is to roll out the insulation blanket and install the new Colorbond sheeting and flashings over the top.

Above: With all metal roof tiles revealed the condition of the 95 year old roof below can be truly revealed.

Benefits of Metal Roof tile replacement

Converting from a decramastic or metal roof tile to a new and insulated Colorbond roof has many benefits. Primarily, a Colorbond roof eliminated the risk of leaks and displaced metal tiles. A new insulated Colorbond roof will also be much cooler and quieter than a decramastic roof. Colorbond roofing is also well suited to installing solar panels, which is impossible with a decramastic roof.

Above: The finished front side of the roof. Transformation was incredible. The chosen colours here are ‘Basalt’ for the roof sheeting and ‘Night Sky’ for all flashings and guttering.

How much does replacing a decramastic roof cost?

The cost of converting from a decramastic roof tile to Colorbond depends on the scope of the overall project. However, a standard-sized house is usually priced between $20,000 and $25,000 + GST. The cost covers insulating the new roof and using quality Australian products with industry-leading warranties.

Before After

So, that settles it then!

Decramastic roof tiles are best removed and replaced with a new Colorbond roof. Not only will you save money in the long run but you’ll also have a much safer and more practical roof over your head. If you’re in the market for a new roof, be sure to get quotes from reputable companies that use time-tested Australian products. You can consult our guide on selecting roofing contractors if you’re unsure of where to start or if you’re looking for a few handy tips. Remember that, as decramastic roofs show us, the cheapest quote isn’t always the best one.

– The Oz-Roof Team

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