Roof Insulation - Legislation

Legislation and mandatory insulation requirements

SANS 10400–XA: Energy usage in buildings

A law introduced that makes it compulsory for roof insulation to be fitted to all new residential homes as of November 2011. The law is because of Eskom’s Demand Side Management (DSM) Plan. Eskom is desperately trying to supply enough electricity to South Africa with limited power sources. The power utility has realized that increasing the supply of electricity (building new power stations) will ultimately take years. Eskom is therefore trying to address the imbalance between supply and demand from the demand side.


Unfortunately due to corrupt contractors and ignorant municipalities, SANS 10400-XA is not always adhered to or inforced, often to the detriment of the home owner. To this day we still get calls from new home owners or developments that complain their house is exessivly hot or cold. Upon inspection we either find insufficient roof insulation or no insulation, when the architects plans and the law says a minimum requirement is legally to be met.


By fitting ceiling insulation, South Africans can take it on themselves to help minimise the inconvenience of load shedding. However, installing roof insulation and complying with SANS 10400-XA needn’t be seen as a grudge purchase. In fact, you get long-term financial savings and a comfortable living space whilst adding to the resale value of your property after the installation of ceiling insulation.

Insulation Climatic Zones

Recent amendments to SANS 10400-XA as of 2021 have now simplified the temperature zones in South Africa. Where zone 2 (Pretoria) required a minimum total R-Value of 3.2, now the new minimum is 3.7. Contact us if you require any further explaination of R-Values and what thickness of insulation your home would require and how your home would benefit from having Thermo-floc® roof insulation installed.

Zone 1

- Cold interior

Total R-Value required - 3.7

Zone 2

- temperate interior

Total R-Value required - 3.7

*previously 3.2

How thickness required is calculated

For our example, we will use a typical tile pitch roof structure or home in zone 2.


Total R-Value require for Zone 1 and 2

  • 3.7

Average R-Value of roof tile, air space and ceiling (without insulation)

  • 0.35

R-Value of insulation required (Total R-Value required - R-Value of uninsulated roof structure)

  • 3.7 - 0.35 = 3.35

Thickness required to achieve specified R-Value (R-Value of insulation required x Thermal conductivity of Thermo-Floc®)

  • 3.35 x 42 = 140mm (However we account for insulation settling and install at 150mm)


If a roof has undertile foil, we can also factor that into the equation as well which will result in a slightly thinner thickness required to meet or exceed the minimum requirement. Thermo-floc® is the wiser choice, thicker and lighter with the same performance or able to exceed minimum requirements.


3.7 - 0.35 - 0.75 (foil membrane)

= 2.6 (R-Value of insulation required)

2.6 x 42

= 110mm (we recommend sticking to the thickest insulation possible as this will ensure a considerably longer performance over any of our competitors)

Give us a call and we will be more than happy to explain your options and exceed minimum requirements and excelling in performance.