IsoBoard is the name of our insulation product. The company is called Isofoam South Africa (Pty) Ltd, established in 1995, with our factory based in Atlantis. We are part of an international construction company, reporting to a South African Group Company.

We have Distribution Centres in Cape Town, Durban and Centurion, as well as stores in George, Port Elizabeth and Bloemfontein.

IsoBoard is a rigid extruded Polystyrene foam, with excellent thermal insulation characteristics in the temperature range -30 ˚C to + 70 ˚C.

IsoBoard is constructed of microscopic gas-filled cells which resemble a honeycomb. This structure gives IsoBoard its very high compressive strength, as well as its near total resistance to moisture transfer.

IsoBoard works well as an insulator because the gas trapped within the cells has a very low thermal conductivity, and the cell walls prevent heat transfer through convection.

Also, the polymer which forms the cell walls is not a good conductor, and the lack of air spaces between the cells prevents heat transfer. IsoBoard is a bulk insulator, which means the thicker the board, the better the thermal resistance.

IsoBoard contains flame retardant gases within its cells, which cause the board to self-extinguish and not spread flame.

The board is always 600 mm wide, and is available in standard lengths from 1200 m, increasing in 600 mm increments to 7200 mm, with the longest length being 8000 mm.

Thicknesses start at 25 mm, then 30 mm, increasing in 10 mm intervals up to 80 mm. The board can be used in combination if greater thicknesses are required e.g. 3 x 50 mm boards to make 150 mm.

The board generally has a tongue and groove edge profile so that adjacent boards may interlock. 80 mm boards are only produced with square edges.

IsoBoard is used when guaranteed performance is required from thermal insulation. We supply to many commercial applications, such as shopping centres and hospitals, where the quality of the insulation determines the size and running costs of the air conditioning plant.

In agriculture, we supply many wine cellars, as well as chicken and pig breeding farms and food processing plants, who like IsoBoard as it is washable, does not support mould growth, and is a superior insulator.

IsoBoard is without doubt the most versatile and reliable of thermal insulators, due to it’s smooth, white, paintable surface which can be used in exposed applications, it’s compressive strength, spanning capability, moisture and flame spread resistance.

The need for energy efficiency has led to more and more home builders and renovators installing IsoBoard, and from middle 2008 it will be mandatory for any new building to be energy efficient, in terms of the SANS 204 addition to the Building Code. There are many actions that can be taken to make a building energy efficient, and the installation of effective thermal insulation is one of the most fundamental and successful interventions.

Determine the following:

For what purpose is the board to be used, and how installed? For instance, a nail-up ceiling will require clips and glue to fix the board. An over-purlin application may require a fitted slipsheet if the board is to be directly under chromadek roof sheets, although not if a Clip-loc or similar fixing system is used.

What lengths of board are required?

If fitting a ceiling, always try to have boards running from wall to wall. Avoid Butt joints wherever possible, and if you do need to install a butt joint, plan the position of the joint within the room in such a manner that you can fit a cover strip of some sort over the joint and make it a feature of the room.

If installing boards over purlin or rafters, make sure that the boards begin and end on a purlin or rafter. Also, make sure that the spanning capability of the specific thickness of IsoBoard for that application is not exceeded.

For cavity wall, inverted roof and under floor applications, the specific length of the board is often not important, however, a shorter board up to 3 m long may be easier to handle.

What thicknesses of board are required?

IsoBoard is a bulk insulator, which means, the thicker the board, the more thermal resistance provided. However, doubling the thickness of the board does not halve the temperature! For instance, a 25 mm thick board installed as a ceiling may have a surface temperature of 29 ˚C on its inside face on a very hot day, while installing 50 mm IsoBoard as alternative may reduce that temperature to 25 ˚C. As a guideline, you can expect the temperature to reduce with between one and two degrees for each additional thickness of IsoBoard installed. The benefits of thicker board are principally that a more stable, constant, predictable and dependable temperature is experienced, and the effect of events such as heat waves or cold snaps is minimised.


Discuss planned lighting, to confirm that it is appropriate. IsoBoard will shrink away from excessive heat sources such as inappropriate downlighters fitted within the board. The guidelines for downlighters are as follows:

Choose a swivel or tilt fitting.

Use an ALU lamp, sometimes called an ALU shield lamp, these have a thicker aluminium coating which reflects light and heat forward.

Alternatively, use energy saver lamps, or LCD’s, which do not release excessive heat.

IsoBoard will soften at 90 ˚C, and melt away from the heat source at 120 ˚C.

IsoBoard Finishes

Determine what surface finish the client requires i.e. IsoPine (100 mm center grooved board, imitating a knotty pine finish) or bevelled or square edges.

Phone or fax your order through to your nearest distribution centre. Builders merchants should always work through the Cape Town Office. You will receive a pro-forma quotation faxed from our office, which serves to confirm your order, as well as details such as delivery. It is essential that this document is signed and returned to us, as no order will commence unless we are in receipt of this order confirmation.

Preparation of orders takes between three and five days, although this may be up to 20 days if yours is a large order which requires manufacture by the factory in Atlantis.

We offer delivery from the regional distribution centres. Most merchants tend to collect their orders, as they have vehicles of their own. We employ a third party distributor, which makes delivery of very small orders relatively expensive. The delivery charge for a small or large volume order is usually the same, unless multiple deliveries are required.

Merchants hold small quantities of stock, usually of a common thickness such as 30 mm, and in two or three lengths, to cater for customers who require board immediately. We supply the board for stock in plastic wrapped packs five and ten, and suggest that the board is sold as a pack where possible. This will keep the board clean, and make it easier to transport.

The board should always be stored under cover, out of direct sunlight and away from the effects of weather.

IsoBoard is fragile and should be transported and handled with care.

The tongue and groove edges of thinner boards such as 25 mm are vulnerable to rough handling, although damaged boards can usually be glued back together, as the IsoBoard will not crumble.

IsoBoard can be cleaned with water and mild detergent when necessary.

The board may develop a surface static electric charge due to the friction of transport and handling. This should be removed at the installation stage by wiping the surface with a cloth dipped in a solution of water and fabric softener. Add a capful of fabric softener to a 10 litre bucket of water. If the static charge is not removed, the board may become dirty from airborne pollutants sticking to the surface, which will need to be washed off.

A product which provides thermal resistance provides a barrier to heat transfer. The better the insulating effect, the longer heat takes to transfer through from one side to the other. Heat always moves from hot to cold, and tries to achieve equilibrium i.e., equally hot on both sides of the product.

Each product has an inherent thermal conductivity, or k value, which is the measure of that products ability to transfer heat from one side to another. Each insulation product also has a thermal resistance or R value, which is described as that products ability to resist heat transfer. The thicker the IsoBoard through which heat must transfer, the longer it takes for the transfer to occur. For instance, 30 mm IsoBoard has a resistance or R value of 1, while 80 mm IsoBoard has a resistance or R value of 2,66 m °C/W.

The k value for IsoBoard is 0.03 Watts per meter per ˚C, which is the long term design value for thermal conductivity of extruded polystyrene of any thickness

Heat transfer is also affected by the thermal gradient, which is the difference between the temperature on one side of the barrier and the other. The larger the difference, the faster heat transfer will to occur. Remember, heat is always seeking equilibrium.

In Summer in South Africa, it is hot outside and cooler inside, so heat flow is inwards into a building. In Winter, the reverse is often true, so heat flows out of the building.

Simply put, installing insulation has the effect of keeping the Summer heat out, and the Winter heat in.

Insulation does not make a building hot or cold, it only delays heat transfer from outside to in, or vice versa. Also, insulation does not necessarily cover the entire building leading to gaps where heat can flow through, so incomplete insulation coverage can be ineffective and inefficient.

Some form of mechanical cooling or heating system is often still required, particularly in buildings where there are many people present and ventilation is required. However, a well insulated building will require considerably smaller plant, and will have far lower running costs than a poorly insulated equivalent building.

Imagine that the temperature around you is 35˚C, or 16 ˚C. One is too hot, and the other definitely too cold for comfort.

The aim of insulating a building correctly is to produce a feeling of comfort for the inhabitants. Generally, people feel comfortable between the temperature range of 20 and 28 ˚C. Within this narrow temperature band, most people are neither too hot nor too cold, and they can adjust themselves to the temperature through simple changes in clothing.

Thermal Insulation should be added to the design of a building envelope so as to ensure that the internal temperatures will remain within the comfort range with minimum intervention.

Always secure the board positively on its long ends and at support points, to prevent movement and possible shrinkage.

Do not allow the board to come in direct contact with a heat source above 70 ˚C, such as unsuitable downlighters. Choose appropriate light fittings for use with IsoBoard.

Clean the board with a solution of fabric softener and water immediately prior to installation, to remove static electricity from the surface.

Ensure that the board is appropriate to span the required distances over purlins or trusses without deflection.

Always use adhesive if fixing the board as a nail-up ceiling together with the concealed clips.

Increase the number of fixing points if installing the board outside under eaves or verandahs in windy areas. Use adhesive every 100 mm.

Only paint the board with water based paints and wood stains.

Do not glue paper backed vinyls or other decorative finishes to the board, as these affect the flame spread characteristics of the product.

Over Purlin

The board is laid in long lengths over purlin under roof sheet from the eave to the roof ridge, butt-joining on a purlin if necessary, and is held in position by the roof screws securing the roof sheets. Remember to reduce the purlin spacings for Chromadek roof sheets to prevent deflection, as chromadek roof sheets get much hotter than standard zinc-alum. Fit slipsheet to the board where Chromodek is used to prevent squeaking, Slipsheet is not required where clip-loc type roof fixings are used, as the Chromodek and IsoBoard are not clamped together. Remember to wipe the surface of the board with an anti-static solution (such as Stay-Soft diluted in water) immediately prior to installation. This reduces the effect of airborne pollutants adhering to the board.

Nail-up Ceiling

The IsoBoard is installed as a normal ceiling fitted to brandering spaced at maximum 700 mm centres. Fixing is through using clips and adhesive. The IsoBoard is held in position permanently by the adhesive, the purpose of the clips is to hold the board in position until the adhesive cures. This can take up to three days, depending on the prevailing temperature and humidity.

Remember to install a perimeter brander all around the room which aids the fixing of IsoBoard, to avoid butt-joints in ceilings and to install appropriate downlighting.

Under Soffit

IsoBoard can also be fitted directly to an existing ceiling, as well as under a concrete soffitt. Fit additional brandering if these surfaces need levelling.

Over Truss/ Rafter

IsoBoard is laid horizontally above the rafters or trusses, secured by screws fixed through the purlins and the IsoBoard into the truss/rafters. The board can be painted before installation if necessary. The purlins should be pre-drilled before fixing the IsoBoard so that the screws center properly into the truss/rafter. When installing over trusses, remember to brace the trusses against top chord lateral deflection under the IsoBoard, i.e. on the visible side of the roof as per architects/engineers specification.

Retrofit Between Trusses or Rafters

IsoBoard can also be retrofitted between trusses or rafters to existing roofs. Brandering is fixed to the upper inside edge of each truss top chord or rafter. The board is fixed to the brandering as for a standard nail-up ceiling, i.e. with clips and glue. It is usually easier to fix short lengths horizontally than longer lengths vertically.

Inverted Roof

IsoBoard is laid above the water-proofing membrane of a concrete roof, below ballast such as paving stones or gravel. This is an excellent use of IsoBoard as thermal insulation, as the board protects the integrity of the water proof membrane against the effects of the weather, and the thermal mass of the concrete slab is at internal as opposed to outside temperature, helping to maintain a constant temperature below. The ballast is necessary to prevent the IsoBoard floating, or blowing away.

Cavity Wall

IsoBoard is fixed horizontally to the inner leaf of a cavity wall. This type of installation is becoming more important, particularly as houses get smaller and the ratio of wall area to roof area increases. Commonly, the South, East and West walls are insulated, allowing the Winter sun to penetrate and warm the north wall, which should be shaded in Summer to prevent heat ingress.

Under floor

IsoBoard is installed either below floor slab or above slab below screed. This is generally to guard against heat loss for under floor heating systems, however, an unheated insulated floor can expect to be between 4 to 5 ˚C warmer than an uninsulated floor.

Suspended ceiling

It is possible to fit IsoBoard to a suspended ceiling grid system, although care must be taken to weigh down each individual board. As IsoBoard is very light, it will lift in response to pressure differences, such as wind, or doors opening and closing. We recommend that the board for a 1200 mm x 600 mm grid is weighted with a piece of gypsum cut to 600 x 300 and stuck centrally to the back of the IsoBoard.

Suspended ceilings using IsoBoard are commonly used when the ceiling plenum is used to deliver chilled air, or for the top floors of offices and hospitals where the roof is not otherwise sufficiently insulated.

Similarly, in airports, IsoBoard can be bonded to noise absorption panels, which are relatively poor thermal insulators.

If the IsoBoard is to be visible, it can be painted to finish. We do not stick paper-backed vinyls or other coverings to the board as these may reduce the otherwise excellent fire performance characteristics of the product.

The chief advantages of using IsoBoard thermal insulation are:

It is an excellent thermal insulator, which can reasonably be expected to last for the life of the building.

The board is available in lengths and thicknesses to suit almost any thermal insulation requirement.

The boards are lightweight, yet very strong and task appropriate.

IsoBoard has Agre’ment Board certification for four of our applications currently, with a fifth in progress.

The boards are very simple to install, and are very cost effective, particularly when used in exposed applications such as ceilings.

The boards inherent resistance to moisture transfer means it will lose very little insulating performance or be damaged if it gets wet.

The flame spread resistance is another proven success characteristic of installing IsoBoard: the board does not spread flame itself, and only those boards in direct contact with flames or excessive heat will soften and shrink away from the flame.

A potential concern when using IsoBoard is the lack of sound reduction through the board. We advise using an 80 mm thick fibrous blanket together with the IsoBoard to soften weather noise on a steel roof, for instance.

Returns are minimal, and are usually because the wrong board thickness or length has been supplied. When IsoBoard breaks on site, it can be glued back together, as it usually has a clean break and does not crumble like expanded polystyrene.

As a plan can always be made to complete the installation successfully, customers are satisfied.

The most common problems that can occur with installing IsoBoard are:

Exceeding the recommended spanning capability of IsoBoard as the board may sag.

Not using adhesive where appropriate, such as ceilings installations as the ceiling may become loose over time.

Fitting inappropriate lighting or downlighters as IsoBoard will shrink away from excessive heat.

When fitting IsoBoard against a chimney pipe, we recommend that a piece of fibre-cement board be fixed to the pipe extending 100 mm above and below the level of the IsoBoard, to prevent possible shrinkage due to excessive heat build-up.

IsoBoard is a thermal insulator and should not be used in isolation to achieve noise reduction. Please consult a specialist with respect to noise reduction systems. (Generally a fibre blanket will reduce sound transmission.)

New Building Regulations

As of the 10th November 2011, the National Building Regulations require mandatory interventions to reduce energy

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IsoBoard Contribution to Sustainability

IsoBoard has performed extensive modeling of various buildings to assess the level of thermal

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Why IsoBoard Works!

IsoBoard is one of the very few manufacturers to present AGED performance values for our products.

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