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Celotex 200mm insulation
Last year’s changes to Part L of the Building Regulations, and in particular the adoption of a method that looks at overall thermal performance rather than specifying individual U-values, have had a significant effect on the way insulation is being used.
Rather than trying to achieve minimum standards throughout a building, specifiers can focus on providing high levels of insulation where it is cost-effective and straightforward to do so, thus making it easier to achieve the overall performance target for the building. This has led to the phenomenon known as ‘thickness creep’ where developers are specifying ever thicker insulation – often using two layers of board to achieve extra performance.
Nobody wants to add thickness for the sake of it, or reduce available floor and loft space, so the best solution is generally the one that offers the best performance in the smallest possible space. One of the most effective insulation materials per millimeter of thickness is polyisocyanurate (PIR) foam board. This is an upgraded version of polyurethane (PUR) that has enhanced fire resistance as a result of its chemical structure.
As well as being around twice as efficient as most traditional insulation materials such as mineral or glass wool, these boards are light, with a high strength to weight ratio, durable, and A-rated for environmental performance in the BRE Green Guide.
This environmental performance, combined with its superior insulation properties, makes PIR board a suitable material for use in developments that seek to meet the Government’s Code for Sustainable Homes. The Code has been introduced to drive a step-change in sustainable house building practice and will form the basis for future developments in Building Regulations.
The Government also sees it as a way for developers to differentiate their product offering and appeal to the growing consumer demand for more environmentally acceptable housing.
The Code measures the sustainability of a home by awarding points in nine design categories – including CO2 emissions and energy efficiency – and with the points being added together to give a star rating. One star is the entry level at which a property can be described as meeting the requirements of the Code, and a maximum six star rating is available for a ‘zero carbon home’. The overall star rating represents performance across all nine categories, and although there is some flexibility in how the overall score is achieved, minimum energy/CO2 performance levels are specified at every level.
These minimum standards are based on a percentage by which the home outperforms the requirements of Part L of the Building Regulations, as calculated using the SAP:2005 method. A 10% improvement is required for one star and this increases in steps up 100% for five stars.
As with the Building Regulations themselves, this makes it very attractive to use as much insulation as possible where it is easy to do so, and then get additional points towards the star rating from other design features. This typically means using thick insulation layers wherever they will fit and thinner insulation layers as a top-up.
Recognising this requirement, Celotex has used its technical capabilities and expertise to develop the widest possible thickness range of PIR board. Boards are available from 12mm, which is the thinnest on the market, up to 200mm, which is by some way the thickest on the market. It also recently introduced a 165mm thick board – the second thickest on the market. With these thicker boards specifiers no longer need to use two layers of board to achieve the Uvalues they want, which saves time on-site, handling, storage space, material and particularly labour costs.
The U-values that can be achieved with these thicker boards can be quite astonishing. On a recent project to build a concept house with a three star sustainability rating for the Interbuild exhibition, 200mm board was able to ensure a ground floor U-value of 0.10 and a roof U-value of 0.08. Values like these show that PIR boards really do perform through thick and thin!
