8 Factors To Consider When Choosing A Metal Roof

by | Sep 16, 2021 | 📁 Metal Roofing

Choosing the right roof for your home is an important decision, with the major deciding factor often seeming to be aesthetics. However, what is often overlooked is the material from which the profile is made which is without a doubt the most important factor to consider. 

In this article we’ll explore eight important considerations when choosing the right metal roofing for your specific application, ensuring that you select a fit-for-purpose roofing profile and material which is suitable for your home and the environmental conditions in which your home is situated.

Base Metal Options 

Did you know that a roof sheet can be produced from different types of metals and these directly influence how long the roof lasts? Metal roofing is typically available in a wide variety of options, including Zinc-coated steel, Aluminum-Zinc-coated steel (sold as Zincal® in Africa), pure Aluminium, Copper, Zinc alloy, and stainless steel.

The most widely used option is a steel roof substrate which comes coated with either a Zinc coated steel or with the state-of-the-art Zinc-Aluminium coating technology. This coating is applied to the steel substrate to protect the base metal from the elements as well as from other corrosive substances found in the air. The Aluminium coating forms an oxide, which provides a tough physical barrier, while the Zinc in the coating provides sacrificial protection. This phenomenon then allows superior protection at the cut edges of the roof sheet. This type of material option is equally suitable for inland and coastal applications, as it is available in different coating thicknesses which cater for the different corrosive conditions. This newer technology is also extremely cost effective and is priced to be competitive against the older Zinc technology.

Roof sheeting made from pure Aluminium is extremely lightweight and commonly used for structures close to the ocean or other highly corrosive areas. It is extremely resistant to corrosion and is available in a variety of colours.

While Copper and Zinc alloy roofing profiles offer longevity, they do attract an extreme premium – on top of the cost of the base metal most of the profiles produced are handmade by various artisans. Thus these roof options are for an individual who is not price sensitive and is looking for a bespoke roof which will truly be one of a kind.

Aesthetics / Design

When selecting a metal roof, make sure the product’s design is an appropriate match for the rest of your home’s construction. Next, choose a material which is fit for purpose and will give you the longevity you desire. You can find quality metal roofing from the roofing suppliers with a national footprint within South Africa. The brands of substrate which are most commonly sought after are ColorPlus, Zincal, Chromadek, Galvanized and Pure Aluminium. Brand names such as these are synonymous with quality and all of them will be available with a warranty from the roll former, so don’t be afraid to ask for the substrates by name. By law, the coil mills are required to print what their product is at no less than three-metre intervals at the back of the sheet. So if your sheet is not printed with the specific brand name at the back then you can be sure you are not getting what you pay for.

Minimum Slope Requirements

Depending on the roof profile you select, there are minimum roof slope requirements for each panel which need to be considered. Consult with your roof supplier to ascertain these details and ensure your roof meets the minimum criteria. The roof profile refers to the shape the metal sheets take when they bend to form panels. A low-slope roof has more complex geometry which is often more expensive to construct because it is a more intricate system to install. However, fewer materials used in the construction of a lower pitched truss means it is less expensive, so the roof as a whole can still work out as a more financially viable option as well as being more modern and aesthetically pleasing. Commercial roofs are typically low slope. Steep-slope roofs are commonly used in residential applications and are ideal for areas which have higher snow loads, and will also prevent the possibility of water ponding on the roof.

Weather Resistance

The most important role of a roof is to protect your biggest investment from the elements. Make sure you consider factors such as prevailing weather conditions when designing your roof. As pretty as a large overhang is, it would be impractical and unnecessarily expose your roof to the possibility of damage. Choosing the right profile is critical in ensuring your roof performs to standard and keeps you dry. For example, a flat roof in a region which gets high snowfall would need to be designed for a dynamic dead load. This means that when the snow falls on the roof it puts a lot of extra weight on the roof – because the roof is flat the snow will lie on the roof and not naturally fall off. If the roof has not been designed for this load then the roof stands the chance of collapsing. Always make sure you consult an engineer and roofing specialist when designing your roof.

The impact resistance of the roof is another important consideration. Although metal roofs are tough, not all are created equal. Aluminium and Copper are softer metals than steel, and therefore more prone to denting. The colour of your roof can also play a major role in how cool your house is and will ultimately affect your comfort while at home. Dark colours attract more heat so your house will naturally heat up quicker. A quick chat with a professional roofing supplier will be able to answer any of these queries and ensure you make the right choice.

Energy Efficiency

Certain types of metal such as Aluminium-Zinc reflect heat more than a galvanized roof. With most roofs, heat reflects best when the sheeting is painted with a light colour such as white or an off-white colour. If your metal roof reflects heat efficiently it can keep your home naturally cooler in warm weather, which can lower energy bills and ensure you live comfortably during the hot South African summers. 


The most vital part to a roof’s longevity are the fasteners used to hold it down. Fasteners are often overlooked and a cheaper alternative is used. A fastener also needs to come with a warranty because using a metal which is not compatible with the sheeting you have chosen causes a reaction known as bimetallic corrosion. This means that the metal is not compatible with your roof sheet and will cause a reaction which makes it rust very quickly. This will cause your roof to rust prematurely and your guarantee given by the roof sheet supplier will be null and void because of the cheap fasteners which were used. The rule of thumb is to use a Class 4 fastener with Zinc-Aluminium and galvanized sheeting, and a Class 5 stainless steel fastener with pure Aluminium sheets. Make sure your fasteners come with a low carbon EPDM washer. A washer is what seals the fastener off against the sheet. If a high carbon washer is used it will corrode the sheet where it makes contact with the metal and your roof will fail.

Finish / Coating

Metal roofing, especially steel, requires a good coating for long-term durability. Product warranty lengths are usually determined by a combination of the metal and the coating. Seek out a finish which has already proven itself in the market. Also, make sure the finish is warranted against fading, chalking, chipping and peeling away from the base metal.

Consider using Safal Group’s Colorplus® pre-painted steel roofing solution which has been designed specifically to endure South Africa’s harshest climates. This product ensures your roof will have a considerable increase in service life, superior thermal protection, added aesthetic value, cost-effectiveness and eco-friendly credentials. The technology used for this coating system also limits chalking and its modified polyesters resist dirt, ensuring your building stays cleaner for longer. With its balance between cost and quality, UV resistance and corrosion resistance, hardness and flexibility, Colorplus® is a standout product in the pre-painted coated steel sector.

Product Warranty

Although some metal roofs offer an expected service life of over 25 years, it’s wise to ensure that your roof has a warranty so that this longevity can be guaranteed. These warranties are determined by a variety of factors including the corrosivity of the area you live in, the pitch of the roof, the grade of coating used on the roof and whether or not the roof has a paint coating on top of its protective coating. Most metal roofing systems should come with a warranty of 15 years or more – if your warranty is any less than this then your product may be of inferior quality or you may have chosen the wrong product for your area.

A metal roof is a major investment for any homeowner so it’s important to know what you’re looking for beforehand so you can be confident in your choice, and pick a roofing profile which will last and add aesthetic value to your building. Contact Safintra today if you require any assistance selecting the right roof to meet your needs.

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