What is an R-value?
An R-value is a unit of measurement used to describe the thermal resistance level of a material – i.e, how much the material restricts heat transfer.
A higher number R-value indicates higher thermal resistance and more effective insulation.
R-values are generally provided in one of two ways: as Material (or Product) R-value, or as System (or Total) R-value.
Material R-value indicates the thermal resistance level of a product or material in and of itself. (Bulk insulation is an example of where Material R-values are used.)
System/Total R-value indicates the thermal resistance value of the total building system – meaning the value of the building materials, insulation materials, and reflective air spaces combined. (The thermal resistance of reflective insulation is generally expressed as part of System/Total R-value.)
Different climate zones have different requirements for System/Total R-values – check the NCC Climate Zone map and the NCC to find out your local requirements.
Which side of the sarking faces out – the foil side or the blue anti-glare side?
The blue anti-glare side is installed facing outwards. This prevents glare when installing.
How does reflective insulation work?
Heat is primarily transferred into and out of a home in the form of radiation. Reflective insulation works by reflecting radiation back in the direction it came from. This means that warmth inside your home in winter will stay in, and heat from outside during summer will be reflected back out. Reflective insulation must be installed adjacent to an air space of 20 mm minimum in order to be effective.
Reflective insulation also reduces condensation in the building structure and provides a barrier against draft and dust penetration.
Why use reflective insulation?
Reflective insulation is extremely effective in climates with predominantly hot weather, like most of Australia. Using reflective insulation in your home can significantly reduce radiant heat transfer, keeping your home cooler in summer and decreasing the need for air-conditioning – resulting in a more comfortable, energy efficient home. You save money, and help the environment!
What is a reflective air space? Why do I need this?
A reflective air space is a gap left in between the exterior cladding of the building structure and the reflective sarking or wall wrap material. Reflective insulation requires this air space in order to be effective – this is where heat is reflected back from the foil. A minimum air space of 20 mm should be left adjacent to the reflective foil side of any sarking or wall wrap.
Reflective foil products installed directly against bulk insulation will NOT be effective.
What is a thermal break? When do I need one?
A thermal break is material with a low level of thermal conductivity, which, when placed in between two conductive materials, helps to inhibit or prevent heat transfer.
A thermal break is required by the NCC for some types of steel frame construction. Check NCC requirements for your particular project before beginning. Where a thermal break is required, we recommend Trade Select™ ThermalBreak™, which has a material R-value of 0.2 in situ and meets all NCC requirements for a thermal break in steel framed construction.
Does your sarking also provide vapour control?
Our range of sarking products provide an effective barrier against wind, dust, moisture and vapour. The vapour control classification is Class 2 Vapour Barrier.
What’s the best wall wrap for double brick construction?
Trade Select™ ThermalCavity™ or ThermalLiner is rigid and flexible convenient to install into double brick constructions.
Why can’t I see the holes in your breather products?
Trade Select’s range of micro-perforated products use next-generation micro-perforation technology and are classified as Class 3 Vapour Permeable membranes.
Traditional breather products have hundreds of bigger (and more visible) holes which can allow a lot of liquid water through the membrane, potentially leading to moisture problems in the building structure. In contrast, our micro-perforated breather products have thousands of tiny, very precise perforations that allow water vapour to escape while providing superior holdout against liquid water, meaning more effective moisture management for your home or building, in particular suitable for brick veneer and drained cavity constructions for NCC, ABCB Climate Zones 6, 7 and 8.
You can see the micro-perforations by holding the product up to the light.
What sort of R-values do your products have?
Aluminium foil in and of itself does not have any thermal resistance – in fact, it conducts heat very well. It is actually the reflective surface of the foil which prevents radiant heat transfer by reflecting heat back in the direction it came from. Reflective insulation MUST be installed with an air space to allow for heat to be reflected back.
For this reason, thermal resistance values (known as R-values) for reflective insulation are expressed as part of the Total System R-value, rather than Material R-value (which is generally used for bulk insulation).
Note: Total System R-value may also be referred to as “Total R-value” or “System R-value” but the terms are used interchangeably and mean the same thing.
R-values for our products vary by product and system, and are provided as Total System R-values for winter and for summer on each individual product page.
If you require more information about R-values for a particular product or building system, contact us!
Do your products retain their R-value over time?
As explained above, the thermal resistance value of aluminium foil is derived from its reflectivity, so R-values will be retained as long as the reflectivity of the product is maintained. Generally speaking, reflective insulation correctly installed will retain its stated R-value for the life of the product. However, certain factors beyond control, such as dust accumulation on upward facing foil surfaces (e.g. in roofs), or poor installation techniques, can cause R-values to decrease slightly over time. (This applies to all aluminium foil products, regardless of the manufacturer.)
For example, foil insulation installed correctly in a sealed wall would not be affected by dust and would retain its R-value permanently. Whereas foil installed horizontally in a roof could be subject to excessive dust accumulation over time which would cause a decrease in R-value. In most cases, however, this decrease is negligible, and R-values are calculated with accumulated dust taken into account. (In many cases, dust accumulation is actually less than what has been allowed for in the calculation – meaning R-values may be higher than stated.)
As a material, aluminium foil is susceptible to environmental conditions, and the long-term retention of R-value depends largely on the environmental conditions where the insulation has been installed. Harsh environmental elements such as salt, ammonia, or even animal droppings can corrode the product and cause decreased effectiveness over time.
Trade Select’s range of products are constructed with a high grade of raw materials and adhesives to ensure superior durability over long periods of time.
Our technical team can help you choose the right product for your specific application and climate zone, to ensure maximum effectiveness of the product in the long term.