Thermal insulation as part of the roof system can keep heat in or out as the season demands, while facilitating compliance with the National Building Regulations.
Whether building a holiday cottage in a subtropical area or a cosy home in a cooler climate, the objective is the same – to ensure internal comfort for the occupants, which would ultimately lead to reducing the demand for and use of electrical energy in heating and cooling buildings.
There are many options available to building designers to achieve this, guided by the National Building Regulations (NBR) SANS 10400 XA Energy Efficiency in Building, which requires significant thermal resistance to be introduced to prevent heat flow through the roof systems of new buildings and alterations.
One option that facilitates compliance with the NBR is the installation of an insulated ceiling, such as IsoBoard thermal insulation. IsoBoard ceilings are highly water-resistant, so it can easily be installed in kitchens and bathrooms. The material is paintable, safe in use and will last for the lifetime of the building without reducing its superb design performance.
According to IsoBoard’s Grant Hoffman, the inclusion of thermal insulation in the roof system provides a heat-transfer barrier, keeping heat out or in as the season demands. An insulated ceiling can be installed to follow the roof profile if one wants exposed rafters, or as a conventional horizontal ceiling.
“From a thermal insulation point of view, in warmer climates it is better to have the insulation further away from the occupants, so it is best to install an insulation ceiling to follow the roof profile. In cooler climates it is important to reduce the volume of space to heat, so having the insulation as ceiling will contain heat within the area for longer and at a lower cost of generation,” Hoffman explains.
“One can also install an insulated ceiling board directly below an existing ceiling structure, rather than removing the original ceiling first. This is a clean and quick way to add the comfort of insulation, as well as possibly repair a damaged ceiling, without the mess of removing the original,” he adds.
Hoffman notes that the thermal resistance required by the NBR is very conservative, which results in very thick layers of insulation if one follows the prescriptive table specific to each climatic zone. A more effective way may be to combine different insulation products, for instance insulated ceiling board and a thermal blanket insulation product, to achieve the required thermal resistance (R-value) at a reduced overall installation cost.
“Using a rational design methodology, one will likely arrive at a required thermal resistance equivalent to a 40mm thickness IsoBoard insulated ceiling, sufficient to maintain a comfortable living temperature throughout the year, with minimum temperature control intervention required,” states Hoffman.
Isofoam SA (Pty) Ltd
Tel: 021 983 1140
Ceiling insulation advice:
Warm climates – high ceilings with insulation following the roof profile.
Cold climates – low ceilings create smaller spaces within to contain heat.