Have you ever wondered how all the components of a building work together to keep a home upright and safe from the elements? One of the most important is the roofing system. The roof contributes to the building’s structural integrity and protects against wind, rain, snow, solar radiation and more. It should also look the part.
At Buildmate, we know a thing or two about choosing the right roof for your property. Deciding its covering is no less important. A few of the questions you might be asking are:
Answer these questions and it will become clearer whether or not you’re on the right track with the right roof covering. If you are not sure, here is our handy guide on what types of roof coverings are available to you in South Africa.
In this post, we are focusing on one of the most popular options – metal sheeting and its many profiles. If you want to know about other materials like tiles, thatch or slate instead, read Part 2 of 2.
Good quality metal roof sheeting offers excellent protection against all types of weather conditions and decay. In South Africa there are several types of sheeting - but the most popular profiles fit into a few main categories:
Corrugated sheets are a widely used steel roofing type that features the classic S-rib profile. This is one of the most popular choices for roof coverings in South Africa because it is easy to fit and good value. The S-rib offers strong structural integrity and is readily available throughout the country. Corrugated sheeting can be galvanised with an Aluminium Zinc coating for added protection against rust.
The naming of roof sheets can get a little technical. Aluminium Zinc coating is often abbreviated to ‘AZ’, as in "Roof Sheet Corrugated 0.53x762mm AZ200 Slate”. The ‘200’ refers to the thickness of this coating, which varies between 100 and 200 microns. When installing a roof sheet on a residential property you will want to use a sheet thickness of 0.47mm or 0.53mm. The width of a corrugated sheet is fixed at 762mm but they can be bought in pre-cut ‘standard’ lengths or cut to size. ‘Slate’ refers to the colour of the roof sheet. The most common colours are Thunderstom, Slate, Raincloud and Seaspray – all variations of metallic grey.
Another budget-friendly option is the Inverted Box Rib (IBR). This has a square-fluted profile. Its key benefits are:
IBR roof sheets have a covering of 686mm and can also be cut to site. They are suitable for commercial, industrial and residential buildings. IBR has become an increasingly popular choice in South Africa. As with corrugate, IBR sheets are available in different lengths, colours, and finishes.
Concealed Fix is a type of roof sheeting application method where the sheets are fixed to purlins with a clip system that are concealed under the sheet. Using a concealed fix system means there is no piercing of the roof sheet itself. This improves water resistance and creates a cleaner roof profile. Because the system uses clips rather than screws the expansion and contraction of the sheet happens without damaging the sheet.
Concealed fix is the preferred system on low-pitched and long-span roofs due to its versatility and the ability to achieve a continuous sheet covering, but it can also be applied to other roof types.
It is important to choose a high quality system. The leading brands on the market are Klip-Lok 700, Saflok 700, Diamondek 700, Springlok 700 & ProLok 700, all of which provide a covering width of 700mm.
Polycarbonate roof sheeting is a versatile material that can be used to cover parts of your roof. It can withstand extreme temperature, filter out harmful UV rays and is fire resistant.
Polycarbonate roofing panels are usually used for skylights, greenhouses, and awnings. They come as a clear glass-like sheet or in a variety of transparent colours, and can be used as a replacement for costlier glass. It is actually 250 times stronger than glass. The main disadvantage is that Polycarbonate sheets are not resistant to scratches so will not be suitable for high traffic areas.
This type of sheeting offers:
Widespan sheeting has various residential, commercial, and industrial applications. It is a popular option for carports, garages and sheds.
Metal sheeting looks great on a wide variety of roof styles including gabled roofs, wood-sided homes, cabins, cottages and modern designer homes. Known for its durability, metal sheeting can come with a long warranty period (it lasts ±50 years). It reflects radiant solar heat so can keep your home cooler and control energy costs in hot weather. It repels rain better than most materials. Best of all, sheets are 100% recyclable at the end of their service life.
Roof sheeting is more expansive per sq. meter than concrete tiles but are also lighter, which means they can sit on a lighter (less expensive) truss.
The high aesthetic appeal of concealed fix IBR roof sheeting has led architects to start using the material as a cladding for the side of buildings. The speed with which IBR sheeting can be installed onto a frame makes this a practical option too.
Metal roofing provides great all-round protection, but it can be noisy during loud weather. This happens if installed directly over the framing as when you have an exposed truss. It is important that your builder uses the correct rubber sealing washers and silicone rubber sealants to seal the sheeting against noise, pull-through and leaking.
If you are living within 1km of the sea then salt corrosion is more of an issue for your roof. Higher grade materials are needed. In this instance, it is better to choose a metal roof sheet with an AZ200 coating. Salt will still build up on any areas that are exposed to rain so it is a good idea to wash your roof with fresh water every 6 months.
Temperature extremes cause all metal to expand and contract. If you live in an area that experiences high temperature variation you will want to do an annual check of the screws and fittings of your roof sheets to ensure they remain tight.
If you are installing or replacing your entire roof you’ll need to get a certificate of compliance. This is governed by the National Building Regulations SANS 10400-L (2001). It is a legal requirement for a new roof to be inspected and certified by a qualified inspector. Once satisfied, they’ll issue an A19 completion certificate. You’ll need this for your occupation certificate. An A19 is also required by most insurers.
The cost of sheeting varies – depending on availability (prices have gone up in the last two years due to global supply chain issues) and the type of material used. For instance, the thicker the AZ coating (which provides greater corrosion resistance) the higher the cost. Your choice of profile (IBR vs corrugated) also affects the price.
Use our handy calculator to estimate the cost for different roof-sheeting solutions.
Don’t cut corners with your choice of contractor. A badly installed roof covering will give you a lot of headaches, and cost more over the long term. You’ll need specialised experts for either steel or tile installation. If you are looking for a tradesman to help with your roof, email us and we’ll put you in touch with one of our contractors.
Are you considering other materials like tiles, thatch, or slate? Head on over to Part 2 of 2 to read more about the other roof covering options available.
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