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IsoBoard Thermal Insulation — extruded polystyrene (XPS)

IsoBoard thermal insulation is a high density, extruded polystyrene rigid insulation board, having a 100% closed cell structure. IsoBoard has been tried and tested internationally since 1970, and manufactured in South Africa since 1995, using a fully automated extrusion process, in accordance with international specifications and standards.

Surface Finishes

Edge Beveled Finish
IsoPine Finish

100mm centre grooved boards, popular for ceilings and exposed applications such as over rafter installations.

Edge Profiles


Shiplap and straight edge profiles on request.

Tongue & Groove

All boards manufacured standard with tongue and groove edge profile.



Standard board lengths: 4800mm increasing in 600mm increments to 7200mm, then 8000mm, the longest board we can manufacture. Length tolerance is ± 5mm.

Board width: Standard effective width 600mm. Width tolerance is ± 2 mm.

Thickness: Popular thicknesses usually available ex stock are 25, 30, 40 and 50mm. Thickness tolerance is + - 2mm Thicker boards of 60, 70 and 80mm are manufactured to order. Thickness tolerance is + - 3mm


Paint Effects

IsoBoard can be painted plain and also painting techniques can be applied to achieve a wood like finish..

Standard Board Colour

IsoBoard's natural colour is white and often not necessary to paint.

IsoBoard Properties

  Standard Conditions IsoBoard
Density (2) ISO 845; 1988 FDIS4898 32–36 kg m3 (± 10 %)
Compressive Strength (5) ISO 844; 1978 10% Strain 160–310 kpa
Water Vapour Permeability (2) ISO 1663; 1981 38°C / 88% RH 0.78 ng/Pa.s.m
Water Absorption (6) ISO 2896; 1987 See note 6 below < 1 % by volume
Coefficient of Linear Thermal Expansion (2) ISO 4897; 1985 -10°C to 60°C 0.067 mm per m per °C
Dimensional Stability EN1604 -10°C to 60°C < 1.0 %
Thermal Conductivity (3)
(average of two tests)
ISO 8302; 1991 (F) 20°C mean temperature.
Dry and 90 day aged
0.024 W/m°C
Long term Thermal Conductivity Five year aged 0.028 W/m°C
Recommended Design Value 90% RH 0.030 W/m°C
Combustibility/Flame Spread (4) Class: B/B1/2/H&V. Refer SANS 428 Classification Table
  1. Determination of physical properties of IsoBoard rigid foam insulation, dated July 1996, by the Division of Building Technology of the CSIR.
  2. Copies of test reports are available from Isofoam (South Africa) (Pty) Limited upon request, or on our website.
  3. Thermal conductivity reports by the general physical laboratory of the South African Bureau by Standards numbered 722/82397 /NK9, 10, confirmed by Guarded HB tests February 2010.
  4. IsoBoard is combustible, with no flame spread characteristics. IsoBoard is suitable for all occupancy types in horizontal and vertical applications, except for buildings where non-combustible materials are prescribed by SANS 10400. (Reports on the fire propagation properties of IsoBoard dated July 1996, by the Division of Building Technology of the CSIR, and further assessments by Firelab to SANS 428 dated July 2007.)
  5. The compressive strength and density of IsoBoard increase with thickness of boards. Thermal conductivity is constant across the density range.
  6. Sample board immersed in water to 50 mm depth for 24 hours. Water absorption is expressed as an average percentage increase over the original volume.
© Isoboard 2012