Installing IsoBoard thermal insulation into your home / building

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We try and answer a number of potential questions you may have regarding the installation of IsoBoard thermal insulation into your home / building.


A) Inverted roof insulation

  1. Why would you use this method? What are the benefits?
  2. What is the uptake in SA? Are many people insulating this way?
  3. Is it also good for insulating normal pitched roofs, or is it mostly used for flat roofs and roofs that are also used as floors?
  4. What is the downside or challenges associated with inverted roof insulation?
  5. What are the most important aspects that need to be considered when going this route?
  6. Do we have the necessary skills locally to do this properly?
  7. Any new developments in terms of technologies or application?

B) Insulating the sides of buildings

  1. Is this important for SA where the focus is more on keeping buildings cool, rather than keeping heat inside?
  2. Are there any building regulations for insulating walls?
  3. What are the most common ways to insulate walls? What role does insulation board play in insulating walls?

C) Performance of installed insulation vs the potential performance

  1. How important is it to consider the performance of the installed product vs its potential maximum performance?
  2. Is there a big difference between the two?



A1: Inverted roofs have the insulation over the water-proofing layer. The benefits are that the entire volume of the roof slab is at internal temperature, insulated from the effects of the elements. The thermal mass of the roof slab assists to moderate the internal temperature beneath the slab. Also, the water proofing layer is protected from weathering, so requires very little if any maintenance.

A2: This is not as popular as it perhaps could be, but is becoming more so as designers and customers apply their minds to energy efficiency solutions, passive building principles and lifetime cost analysis.

A3 Flat roof, gentle drainage slopes. The insulation needs to be secured in place by ballast of some form, so this solution is not suitable for severely sloping roofs.

A4 Generally speaking, it might be the weight of the ballast that is required, if the roof hasn’t been designed for it, or the availability of suitable drainage systems. No real challenges, the IVR is a very elegant and simple solution.

A5 Choosing appropriate insulation. The insulation material is exposed to water effect. Insulators which absorb water are not suitable.

A6 As long as the roof is properly designed to accommodate the mass of ballast and the correct drainage of water from the roof, installing under supervision is very simple.

A7 Not so much new technologies, as new uses for roof systems: As space becomes more valuable, people turn to green roof systems, roof top urban farming, Aquaponics, roof entertainment areas, living space, parking space, perhaps helicopter access.


B1 Insulating the sides or walls of buildings is important, as part of the overall heat control solution for any building. Heat flows through the easiest route. As buildings get smaller, the ratio of roof to walls decreases, meaning walls have increasingly more influence on the internal temperatures. Also, in steel framed buildings, if the roof is well insulated but not the walls, heat will flow in through the walls, and become trapped under the roof insulation. In some climatic zones in South Africa, keeping heat in in winter is more important to energy efficient usage than keeping heat out in Summer, such as the Western Cape.

B2 Not for masonry walls, however there are requirements for lightweight walls, such as timber or steel frame constructions, which must achieve a minimum thermal resistance, depending on the climatic zone in which they are constructed. Wall insulation can play a big part in limiting heat flows in a building, and as such are frequently considered as part of a rational design energy usage solution, as this will invariable be a cheaper solution than prescriptive compliance. Rational designs allow greater freedom of design expression, while keeping projects affordable. For instance, introducing wall insulation can eliminate costly glazing solutions.

B3 In new buildings, masonry walls can be insulated by fitting a rigid insulator like IsoBoard between the bricks. A retro-fit alternative is EFIS, (External Façade Insulating Systems) where insulation boards are placed against the outer wall of existing buildings, then covered or rendered with a protection of some sort. Very popular internationally, particularly with light weight frame buildings, to bring existing building stock up to current regulatory standards for energy efficiency, but not common in SA as yet.


C1 Insulation is affected by many factors, the most insidious of these being water. When choosing insulation for an application like inverted roofs, choose a product that is least affected by water, i.e. IsoBoard. When we advertise a reliable design value IsoBoard, we allow for a full 25% deterioration in the performance of the insulation over time, due to water absorption and the substitution of the original blowing agent with air. IsoBoard installations which are re-tested after long periods of installation in the harshest conditions have proven that the design value is appropriate, and can be relied upon by architects, engineers and customers as the worst case thermal performance of IsoBoard, and that this value can be sustained for the life of the building. This is particularly useful for concealed applications, such as inverted roof or cavity wall.

C2 There is always a fall-off in thermal performance over time in insulation products. The reasons for the degradation in insulation value vary as per type of product, and application. Buildings where this is not considered and anticipated will not achieve or sustain their energy usage design objective.