CONCETE ROOF TILES - THE MOST ECONOMICAL AND BEST LOOKING ROOFING MATERIAL:

First conducted in 2003, the survey uses data gathered in February this year from many sources. It focused on three building models, a 57m² (floor area) house, a 134m² house and a 1 158m² commercial building. The results of each will be published by the CMA in three leaflets in May, one for each model.

CMA director, John Cairns, said the survey assessed complete roofs built with trusses which allow for the inclusion of ceilings and underlays, and in each case concrete tiled roofs proved the most cost-effective material.

“An increasing number of low-cost housing developments are using roofs built with trusses as they have better insulation and aesthetic properties and ultimately, make for much sounder long-term investments,” observes Cairns.

Factors such as floor area, roof area, pitch and truss spacing, among others, as well as cost factors such as truss and timber sundries, roof erection, roofing material and fixing, were taken into account.  Prices were based on complete roof structures, however, fascia boards and gutters were omitted from the survey because these are optional items which make no difference to the costing. Likewise no provision was made for underlay, membrane or ceiling construction.

Certain assumptions were made to simplify the costing model for these houses. For instance, while some housing developments comprise many units and developers/contractors can negotiate special project discounts, the majority of builders construct one-off houses and are therefore obliged to source roofing materials from their local suppliers at less advantageous prices.

The survey takes the following into account:

• Roof truss prices are based on standard industry pricing practice
• All cost are based on February 2007 figures
• Labour costs for the erection of the timber structures and the fixing of the roof covering material are included in the cost comparison
• General sundries exclude fascia boards and barge boards
• The cost of gable masonry has been excluded as it is constant for all roofs
• The rates exclude VAT
• Waste is included in all calculations
 
The updated survey focuses on two models for concrete tiled roofing in the 57m² house category, one using a conventional concrete tiled roof, and the other deploying a roof using The CMA Roofing System. The latter, which has been awarded an Agrément certificate, was introduced two years after the first survey to make concrete tiled roof even more affordable, and the results of the current survey confirm this.

The R/m² costs for a concrete tiled roof on the first model at R187 are 11% lower than the next most cost-effective material, corrugated iron sheeting at R209, whereas, the R/m² costs for the model using The CMA Roofing System are 17% lower at R179. The first model was also compared with other materials such as corrugated fibre cement, pre-painted IBR metal sheeting, and pressed metal tiles.

The survey revealed that a conventional concrete tiled roof at R187 costs 20% less than the R232 of corrugated fibre cement, 21% less than pre-painted IBR metal sheeting at R235, and 35% less than pressed metal tiles at R287.
 
Pre-painted metal sheeting, pressed metal tiles, fibre cement slate and Alumaz natural slate were the materials selected for comparison with through-colour concrete roof tiles on the 134m² house and the 1 158m² office building.

The R/m² costs on concrete roof tiling for the house at R228 was eight percent lower than that of pre-painted IBR sheeting at R248. They were 27% lower than the R311 of pressed metal tiles, 46% lower than fibre cement slate at R355, and 50% lower than Alumaz natural slate at a cost of R448.

The R/m² costs on concrete roof tiling for the office building at R288 were 13% lower that that of pre-painted IBR sheeting at R329. They were 21% lower than the R362 of pressed metal tiles, 32% lower than fibre cement slate at R421, and 44% lower than Alumaz natural slate at a cost of R514.

Certain assumptions were made to simplify the costing model for the office building. For instance the floor area of 1 158m² was chosen arbitrarily and has no special significance other than being fairly representative of architectural practice. The roofs were all pitched at 26º as it was felt that in most circumstances this would be an architectural design feature of the building.

Cairns says what the survey clearly demonstrates is that property developers can have the best of both worlds on roofs built with trusses – attractive concrete tiled roofs which enhance the value of residential and commercial property at the most cost-effective prices. 

The timber framework of a typical example of The CMA Roof System is subjected to stringent load testing prior to the issuing of an Agrément certificate.

The Golf Course Ext Development, an affordable housing initiative adjacent to the King Williams Town Golf Course, in the Eastern Cape, the first housing project in which the recently introduced CMA Roofing System was used.

Concrete roof tiles are laid using the CMA Roofing System.