2. Wall Insulation

  • Masonry Cavity Wall Insulation

Masonry walls, inclusive of collar jointed and cavity walls, shall comply with the requirements of SANS10400-K (Walls). External walls are defined as the complete walling system, as measured from the outer skin exposed to the environment, to the inside of the inner skin exposed to the interior of the building, and does not include glazing.

The Minimum total R-value requirements for an external wall with a surface density greater than 270kg/m² shall be as per below.

Minimum R-value requirements for walls with a surface density greater than and equal to 270 kg/m²
Walls – Mandatory Non-mandatory
but sensible: with Insulation
(alphabetically)
Surface Density Energy Zones R-Value Example +50mm
EPS
+50mm
MW
+50mm
PU
+50mm
XPS
Generic R-Value of Product
R=1.43 R=1.52 R=2.00 R=1.79
Total R-Value of Wall System
(Cavity + Insulation)
>270kg/m2 1 0,5 50mm cavity wall, plastered internally 1.93 2.02 2.5 2.29
2 0,5 50mm cavity wall, plastered internally 1.93 2.02 2.5 2.29
3 0,35 Collar jointed wall, plastered internally
4 0,5 50mm cavity wall, plastered internally 1.93 2.02 2.5 2.29
5 0,35 Collar jointed wall, plastered internally
5H 0,35 Collar jointed wall, plastered internally
6 0,5 50mm cavity wall, plastered internally 1.93 2.02 2.5 2.29
7 0,5 50mm cavity wall, plastered internally 1.93 2.02 2.5 2.29

Key: EPS: Expanded Polystyrene, MW: Mineral Wool, PU Polyurethane and XPS: Extruded Polystyrene.

Note: R-values quoted are generic. For actual figures obtain thermal values from manufacturers.

  • Typical Construction Details of a Masonry Cavity Wall with Insulation

    • Wall insulation in Light Steel Frame Construction

    External walls with a surface density lighter than 270kg/m² shall achieve a minimum total R-value of:

    1. a) 2,2 m²K/W for energy zones 1, 2, 6 and 7; and
    2. b) 1,9 m²K/W for energy zones 3, 4, 5 and 5H.

    A walling construction that has any metal sheet, metal studs, metal tracks or metal battens fixed to each other shall have a thermal break consisting of a material with an R-value of not less than 0.2 installed between the metal structural elements.

    Typical Construction Details of a Fibre Cement Board External Cladding System

    R – Value of basic elements of wall: 0,245 m².K/W (Note: Fire resistance to exceed 30 min.)
    Energy  zone 1, 2, 6 and 7 3, 4 and 5
    Minimum total R–value 2.2  m2.K/W 1.9  m2.K/W
    Indoor air film 0.12 0.12
    Outdoor air film 0.03 0.03
    9mm fibre cement 0.025 0.025
    15mm Gypsum boards 0.07 0.07
    Minimum required added R–value  m2.K/W 1.96 1.66

    Typical Construction Details of a Fibre Cement Board External Cladding System