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Roofing Installation

Roofing - What are the Options?

Review of Design, construction and installation of roofing and waterproofing or damp proofing in Johannesburg. We’ve come a long way since our ancestors selected cave living as a way to keep a roof over their heads and keep themselves protected from the elements. Today roofing has evolved to an art and it is not unusual to expect a roof to last 100 years, quite amazing when you consider the amount of damage a roof has to withstand from the onslaught of sun, rain and other things. Building professionals have tested what works the best and what doesn’t and today can offer reliable assurances that your roof will not leak or fall down and kill you.

Perhaps the most common roof we see in South Africa (in fact worldwide) is the wood framed or trussed method. The most important aspect of any roof is its frame; it is also what gives a roof its pitch, or steepness. The pitch given to a roof is more than aesthetics, it is practical too. In areas where bad weather is the norm, the steeper the pitch the more practical it is. While we don’t experience snowfall in South Africa, those countries that do generally use a steep pitch as this allows the snow to slide off instead of having to climb up and shovel it off. Not necessary in South Africa and we would use a steep pitch for design aesthetics only.

The Construction of a Roof

Roofs are made in a variety of shapes and materials, generally manufactured offsite they are delivered completely assembled, ready to be installed.

Roofs need to be designed and constructed very well as they not only protect us from the elements the also protect the structure beneath them be providing structural support for superimposed loads.

Modern roofing comprises an outer roof which is attached on top of a deck surface which in turn is supported by a primary framework or structure that comprises beams, arches or trusses. The shape of the roof is dictated by the materials and the deck of the structure below.

Roof shapes comprise anything from completely flat to three dimensional, spherical, pyramidal or even two sloping decks intersecting in a line.

A roof is built upwards from the structure of the building below. Its primary framework rests on the walls or columns of the structure of the building which in turn supports the roof deck which is responsible for carrying the roofing assembly. The structure of the building is framed with girders and the beams that rest on them are connected to these. The roof deck spans between the primary framework and are anchored to them.

Once this is all in place the next step is to sheath the roof deck generally using structurally sound plywood and then apply what is called roofing felt or insulation. This is attached to the roof deck and its purpose is to provide greater protection from the elements. In South Africa this is probably better known as “areolite”.

The final step is to apply the exterior finish which is what gives the building it’s over look. What you choose to cover your roof depends on where you live, what your architectural influences dictate, what you can afford and what overall style or appearance you are after.

Whatever you choose, remember that this final stage of completion and should only be done by a professional. Unskilled labour at this point can be very cost prohibitive as well as leaving you exposed to the elements if it goes wrong.  

Roof Shingles or Tiles?

While not the only options in roof cladding shingles or tiles are perhaps the most prolifically used. Let’s start with shingles.

Shingles consist of individual elements that overlap each other. They are usually flat and rectangular in shape. They are laid in single rows without touching sides and are laid from the bottom edge upwards, overlapping each other as they go by as much as a third of their length. Shingles come in a wide range of materials which include asbestos, cement, ceramics, natural stone or slate. They are even available in a bitumen soaked type of paper which is then covered with an aggregate, or asphalt. However due to the fire hazard that these shingles present, they are slowing being replaced by fibreglass versions.

Roofing tiles on the other hand are available in many modern materials such as concrete and even plastic, clay or ceramics. They are designed to be “hung” from the roofing framework and then fixed with nails. These tiles are generally ‘shaped’ or have profiles, but can also be flat. Flat tiles are the simplest form of roof tiling and are laid in the same manner as shingles are.

Many tiles are shaped for reasons of practicality, one being the ability to channel water away while giving them the ability to interlock with each other when installing. For instance a Roman tile would be flat in the middle with concaves curve at one end and a convex curve at the other which allowing each tile to interlock with its neighbour.

Pantiles offer an S shape profile which allow interlocking and once complete the overall effect is of a “ploughed field”, while the barrel tiles are semi cylindrical and are laid in columns each one consisting of the convex side while the other consists of the concave side.

Of course there are many other shapes, colours and varieties which all give their own unique completed look and finish.

Mention should also be made of corrugated steel roofs. Steel roofs have a place in modern building still, yet are predominantly found on warehousing or industrial type builds. If put to use in a residential application steel roofs provide a particular appeal as well as a definite type of “finished look”. However they can be noisy in rainy weather and in hot climates need to have special attention paid to the level of roofing insulation installed in the home. Usually applied in sheets, they are laid in rows and nailed to the roof framework.  

Eco Friendly Plastic roofing

Plastic roofing, or more precisely polyethylene roofing is applied in sheets, much like steel roofing. Fixed directly onto the roof framework, plastic roofing offers a homeowner up to 20-25 years lifespan. They are available in many colour choices, offer good UV protection, will not rust or break, offer good temperature isolation, will not oxidise, are lightweight and easy to install, are not brittle and are very price competitive.

Whatever your personal choice of roof cladding, the basic construction of any roof remains the same, are construction from much the same materials and offers a homeowner pretty much the same lifespan.

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