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rci 001Contractors install insulation in a roof.  
Image credit: CLS Renewable Energy

State and local building codes typically include minimum insulation requirements however, it is more cost-effective to add insulation during construction than to retrofit it after the house is finished. “Government regulations introduced in 2011 specify minimum insulation levels for all new homes and buildings built in South Africa,” says the Thermal Insulation Association of Southern Africa (TIASA).

The energy efficiency legislation for new buildings SANS 10400-XA has been published by the regulator (NRCS). All new buildings need to comply with the performance parameters, which means that insulation will be installed to achieve the stipulated R-values (thermal resistance). Home insulations are fully compliant with these new regulations!

South Africa has been divided into six climatic zones according to humidity and temperature variations. These are cold interior, temperate interior, hot interior, temperate coastal, sub-tropical coastal and arid interior. The NRCS has a detailed report on which city falls into which zone.

Well designed and insulated homes that use an insulation that meets the South African requirements will give all year comfort. Additionally, it will cut the heating and cooling costs. Which in turn reduces greenhouse gas emissions. Choosing the best ceiling insulation for your situation is an important factor.

rci 002Contractors install insulation in a roof.
Image credit: Pinterest

The appropriate thickness will be influenced by climatic conditions. You will need to establish if you are trying to keep the heat in, keep it out or both. Ceiling insulations are effective against daily temperature changes as well as seasonal changes.

Choosing ceiling insulation
When choosing the right ceiling insulation, there are two main categories to choose from – reflective or bulk roof installation. You can get an even greater insulating effect by combining reflective and bulk insulation.

Examples of combined insulation would be factorylite, which is aerolite combined with a reflective insulation. Isofoil which is isotherm combined with a reflective insulation. The R-value of the product determines the products ability to resist heat flow. The higher the R-value, the better insulating affect you will get out of the product.

Aerolite and Isotherm bulk ceiling insulation
Bulk insulation is excellent for resisting convected and conducted heat. The air pockets inside the insulation traps the heat. Thermal resistance works the same way, and it makes no difference which way the heat flows through it.

Additionally, bulk insulation and reflective insulation are the two types of insulations currently on the market. The leading bulk insulations are think pink aerolite, which is a glasswool roof product. Isotherm ceiling insulation is a polyester material. Bulk insulation comes with an R-value that differs according to which thickness of insulation you require.

Well designed and insulated homes that use an insulation that meets the South African requirements will give all year comfort.

Reflective insulation
Radiant heat flow is resisted by insulations with reflective properties. This is achieved because the insulation is highly reflective and it can re-radiate heat. There is a 25mm layer of air that the reflective insulation relies on next to the shiny surface. Heat flows differently through reflective insulation depending on which direction the heat source is coming from.

Reflective foil is made from aluminium and is laminated to paper or plastic. You can get a decrease in performance from reflective insulation when dust settles on it as dust reduces its ability to reflect. The shiny foil surface should always face downwards. The anti-glare surface of single sided foil should always face upwards or outwards.

Up and down R-values are supplied with reflective insulation. You get a different R-value for each thickness. Always make sure the values given by the manufacturer relate to what you are looking for.

Fixing the errors
Leaks, roof moisture and fungus are the most visible consequences of improper maintenance. Poor insulation promotes heat from escaping through the layers of roofs leading to leaks and flooding from rain. This process becomes detrimental to the roof and leads to deterioration and destruction of the membrane, flashings, gutters and downspouts.

Each type of roof should have carried out calculations of temperature and moisture. The aim is to not only select the correct thickness of thermal insulation, but also eliminate the possibility of condensation between the layers of the roof and eliminate conditions conducive to the growth of mould on the ceiling and walls on the inside. These calculations consider the space around windows, skylights, roof hatchways and so on. These are the places where moisture frequently occurs and are favourable conditions for mould growth. With inadequate ventilation, steam and moisture within the layers cause separation and can be seen visually on the ceiling and wall in the form of streaks and peeling paint coating, which are signs of weakness in a roof’s waterproof seal.

rci 003A roof, ceiling and insulation installed correctly go a long way.
Image credit: Homeless Turtle Sanctuary

Waterproofing on every roof, regardless of its function, is crucial. The most common cause of leaks is due to errors by the contractors, such as lack of knowledge of the technologies used and a lack of a qualified team of employees.

A common mistake is to use alternatives or materials other than those provided by the manufacturer or chosen and described in the project documentation. The resulting ‘saving’ for the difference in price of material is usually superficial and disproportionate to the cost of any subsequent repairs.

Source: Home insulation and Alta Roofing and waterproofing


  • 45% on cooling and heating energy can be saved with roof and ceiling insulation
  • 20% additional cooling and heating energy with wall bulk insulation
  • 5% on winter costs with the right floor insulation used in your home

 Source: Home Insulations


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