building process


  • Creation Date: Wednesday, 29 May 2019

When most people think of insulation, it is mostly with regards to what is over the ceiling but there is so much more involved than that. An issue to consider is that many contractors, particularly those in the bakkie brigade, do not always read or understand the notes on the architect’s plan and simply assume that the insulation that they have traditionally installed is what is required and so they do not allow for it properly in their pricing structure. This either leads to cutting corners or argument, both of which can be avoided by knowing what to look for in your project.

  1. Foundations and floor slab.

The correct method of applying insulation here is to place a minimum 25mm sheet of polystyrene or polyurethane against the inside edge of all external walls and on both sides of internal walls from the top of the foundation to the underside of the floor slab. This must be done before they backfilling and compaction of the under floor-filling. The next is to place a minimum 25mm sheet of polystyrene or polyurethane under the entire area of the floor slab, on top of the compacted fill. This will effectively insulate the floor and thereby increase the effectiveness of the other insulation in the house but also increase the effectiveness of any underfloor heating that you may wish to install.

     2. Walls

Until recently, it was unknown to insulate the walls of your house but now it is prudent and soon to be a requirement, that all cavity walls are insulated with a 25mm sheet of polystyrene or polyurethane fixed to the outside of the inner skin of brickwork. This is particularly important when building with cement bricks which tend to be somewhat more porous than baked clay bricks.

  1. Roof spaces.

When it comes to roof spaces, your architect/designer would need to have specified what insulation is required in your roof structure to meet the energy efficiency insulation requirements for the Climate Zone that you are in. The important issue here is for both yourself and your architect to make sure that the specified insulation is being installed. The difference between a 75mm and a 100mm polyester blanket is difficult to spot once it is installed but it will make a difference to your comfort and your pocket if the thicker blanket was specified and paid for but the cheaper one was installed.

Further thought would be to consider the design and covering materials that are specified. Designing a ventilated roof, for instance, will tend to lower the temperature inside the roof space which in turn will make the insulation more effective. Different roofing materials would also have a differing effect on the temperature inside the roof space.

Once again, it is a requirement that your architect/designer calculates and specifies the glass that goes into the various windows or doors in your house. The specification will also vary depending on the orientation of the house. This is an issue that you should discuss with your architect as performance glass can become very pricy but designing shading elements into your house will affect the type of glass that needs to be installed. This will also have an impact on your pocket and small changes in the design can make a difference in the price of the glass.

The effects of proper insulation will not only be felt on the day of extreme heat or cold but there will be much longer term effects on your energy bills as there is a less of a requirement for heating or cooling your house. Consider a short term financial outlay for a long term financial gain and live in comfort.

Article written by Les Abbott. PrArch. L A Design Studio.