Isotherm Thermal Insulation maintains a comfortable indoor climate all year round; keeping interiors warm in winter and cool in summer. Isotherm is made from polyester and is 100% people-friendly. It is safe and easy to install; no protective clothing required and is non-flammable.

Isotherm is an Agrément Certified product. Isotherm is economical and the best thermal insulation product to use in terms of guaranteed quality and does not collapse after time and is maintenance-free.

Made from recycled PET bottles, Isotherm helps to fight unemployment and sustain the ecology and economy of the country. Isotherm is 100 % recyclable.

Isotherm saves energy thus installation can pay for itself, through savings in electricity.

Isotherm Thermal Insulation Characteristics

Isotherm Thermal Insulation is made from 100% thermally bonded, people-friendly polyester. The polyester fibre is produced from recycled PET bottles. The soft texture of Isotherm insulation makes it easy to roll out and cut to size. Pleasant to touch, simple and safe to install. No loose fibres or itching. It is non-allergenic, non-irritant and resilient. Providing excellent thermal and acoustic insulation, Isotherm is ideal for use in both roofs and walls.

Get the R-Value

  • The R-Value is the measure of an insulation product’s ability to restrict heat transfer. The R-Value is therefore indicative of an insulation product’s thermal insulation performance.
  • The higher the R-Value the better the performance and effectiveness of the insulation product.
  • The R-Value of Isotherm is dependent on the thickness selected.


Up R-Values

This is the resistance to the upward flow of heat; sometimes referred to as “winter” R-Values or warming.

Down R-Values

This is the resistance to the downward flow of heat; sometimes referred to as “summer” RValues or cooling.

Total R-Values

This is the total resistance provided by a roof or ceiling assembly and /or wall. Total R-Values are the best indicators of performance.


  • 40 mm  –  0.88
  • 50 mm  –  1.10
  • 75 mm  –  1.65
  • 100 mm  –  2.20



The pH value of 7.8, determined as between 6.0 and 9.0 such that it will not affect or be affected by materials with which it is likely to come into contact. Tested in accordance with SANS 1381: Part II (Loose Fill Thermal Insulation Material, 3.10)*

Fire Behaviour 

  • Isotherm does not support combustion when installed as specified and used in applications described.
  • Isotherm may be used as specified for all types of buildings subject to the Provisos listed in Part T of Section 3 of SANS 10400*)
  • ASTM – E84:       Spread of flame = 0   |   Smoke index = 160   |   Smoke toxicity = <1 (low toxicity)
  • SANS 10400 – 1990. The application of the National Building Regulations.*
  • Max service temperature is 180°C


Chemical and Physical properties

  • Composed of polyester.
  • The relatively high melting point of polyester fibres gives ISOTHERM good thermal stability.


Moisture Absorption

  • Isotherm does not absorb more than 2% (by mass) of moisture, which is within the limits set by the standard.
  • Tested in accordance with SANS 1381: Part I (Materials for thermal insulation of buildings)*



  • Isotherm is non-toxic. If wet with water,Isotherm will not emit objectionable odours nor will it lose any of its benefits on drying out.


Quality Management

  • Isotherm’s quality management scheme complies with Agrément South Africa’s requirements.
  • Agrément South Africa’s requirements are based on SANS 9001:2000 Quality Management Systems.*


Durability Settlement and Handling

  • Isotherm does not physically deteriorate over time and does not require maintenance. Tested in accordance with SANS 1381-1, 3.9.*
  • Isotherm is not damaged during normal handling and installation.


Temperature Range and Resistance to bacterial attack

  • For the uses described, ISOTHERM will not be exposed to temperatures that will affect its material properties, which are less than -50oC or greater than +180oC.
  • Isotherm has good resistance to bacteria, fungi and mildew. In addition fibre-devouring insects will not damage
  • Isotherm since it is indigestible. BS279: Methods of Testing for Inorganic Thermal Insulation*


Resistance to condensation

The installation of Isotherm above ceilings will reduce the likelihood of condensation forming on walls and ceilings. Condensation and associated mould is less likely to occur on the underside of Isotherm insulated ceilings.

Health and Safety

Isotherm is made from polyester which is considered physiologically inert and will not shed fibres. Fibres are thermally bonded as opposed to glued with adhesives, which may deteriorate over time. Isotherm is non-irritant and non-allergenic. No loose fibres are shed during handling, cutting and shaking.