Ensuring insulation fits for improved thermal performance

Buildings are responsible for nearly 50% of the UK's energy consumption and carbon emissions. Well-insulated existing and new-build properties will help improve that figure, but only if the insulation is correctly fitted in the first place. Global leaders in PIR manufacture, Recticel Insulation, provides a guideline to installation practices and techniques in respect of one of the more innovative insulation products on the market.

A Green Building Council report released earlier this year revealed 25 million homes need to be refurbished by 2050 in order to meet insulation standards, and achieve the UK's pledge to cut carbon emissions by 80%, by then in line with the 2008 Climate Change Act. Excess energy used to heat draughty buildings is a major contributor to the country's carbon footprint, hence the need for quality insulation that is fitted to a high standard.

The onus on providing buildings which deliver in terms of thermal performance will largely fall on architects, developers and the building industry as a whole. However, manufacturers can also play their part by continuing to refine the properties and performance of ‘fabric first' materials which are so vital in putting a thermal seal on the building envelope.

Innovative solution

Dedicated to raising the standards of insulation products in the UK, Eurowall + represents Recticel Insulation's commitment to PIR innovation to improve a building's thermal performance and enhance the comfort and wellbeing of its occupants. Eurowall + was the first rigid insulation board to feature a tongue and groove joint on all four sides. This interlocking feature ensures boards slot together easily to provide insulation that is solid and airtight and minimises heat loss caused by thermal bridging, as well as offering effective protection against elements such as wind-driven rain.

In the quest for improved energy efficiency, designers can be left with little option but to increase the thickness of insulation in a dwelling's external walls. This additional insulation can be added internally, externally or within the cavity, all of which mean that floorplans need to be enlarged, which for housebuilders can mean smaller rooms or fewer houses per plot.

Eurowall +, a premium, full-fill cavity insulation board manufactured from high performance closed cell polyisocyanurate (PIR) foam, has been developed to allow designers and housebuilders to maintain traditional build techniques, without compromise to thermal performance. It's resulted in a board that achieves a U-value of 0.18W/m²K to enable compliance with Part L1A of the Building Regulations 2013 in England and Part L1A of the Building Regulations 2014 in Wales.

Installation made easy

Installing Eurowall + couldn't be easier. To help the installer fit the boards the right way, there is a different gas-tight foil-faced finish on each side: one is distinctive grey alkali-resistant facing for placing against the inner leaf; where wet cement can affect the foil facing. The other is a low emissivity multi-layer aluminum facing which enhances the thermal resistance of the cavity.

Eurowall + eliminates the need to tape board joints, whilst the boards themselves should be installed in a brick bond pattern with staggered vertical joints.  Wall ties should be applied in the same way as if a partial-fill board were being installed. This involves cutting a slot in the tongue joint with a trowel then pushing the wall tie into it. Retaining discs fit onto the wall ties, acting as a spacer to help maintain the 10mm cavity. 

In terms of reveals, wall ties continue to be installed at every second course of blockwork, rather than every course, as is common practice. Two ties are positioned within 225mm of the reveal. Corner details are formed by cutting the boards squarely and closely ****-jointing. A vertical 300mm wide DPC covers the corner and runs the full length of the junction. Cavity trays are fitted by either cutting the insulation at an angle and running a DPC over the top of it,  or using a partial-fill board behind the section where the DPC is due to be fitted.

Case study: Gerrards Cross, Buckinghamshire

Eurowall + was used by Mentmore Homes in the construction of two energy-efficient, detached five-bedroom homes in Gerrards Cross, Buckinghamshire, valued at £2.5 million each. The high-quality, traditionally-constructed homes feature external walls built using brick/block cavity construction. Cavity wall is the UK's most common method of wall construction for residential dwellings. For Mentmore Homes, a significant challenge was to retain a standard-sized cavity while complying with the latest Building Regulations.

To maximise the thermal performance of the external walls without increasing the width of the 100mm wide cavity, Mentmore Homes specified Eurowall + full-fill insulation. Using this high-performance PIR insulation board enabled the developer to meet the thermal performance required to achieve Building Regulation compliance.

A total 500m² of Eurowall + boards were used in the wall construction of the two houses. Nicholas Peck, contracts manager at Mentmore Homes was impressed with the performance of Eurowall +: “We wanted to make the properties as energy efficient as possible; to make this happen the best place to start is the insulation,” he said. “Specifying Eurowall + meant we didn't have to increase the size of the wall cavity and lose space inside the properties”.

The panel's interlocking feature was another element of the product that Peck says was beneficial: “Eurowall +, because it slots together so easily will remain solid and airtight,” he said. “We required a high-performance product for this extremely high-profile project and Eurowall + didn't disappoint”.

Case study: Hedge End, Southampton; Ludgershall, Andover

Ease of handling and simplicity of installation were just two of the reasons Foreman Homes selected Eurowall + to insulate the walls of the homes on two large housing developments in the south of England. The schemes at Hedge End, Southampton, and Ludgershall, Andover, together contain a mix of over 300 plots of social and private housing; homes vary in size from two- to five-bedrooms.

Mark Kew, a bricklayer with Foreman Homes, applauded the benefits of using Eurowall +: “In 35 years' experience in construction, the insulation developed by Recticel is easy to cut accurately due to the grid printed on the foil-facing side which makes it easy to install with minimal waste. I can honestly say our quality and speed have excelled as a result of its use.”

In total over 15,000m² of Eurowall + insulation was installed. For Foreman Homes, using Eurowall + meant the homes' external walls could be built quicker and easier resulting in a corresponding saving in construction costs.  And, the full-fill insulation's excellent thermal performance will mean that residents on both developments will be able to enjoy their comfortable, energy-efficient dwellings.

As these case studies demonstrate, innovative PIR products such as Eurowall + contain a host of benefits to fit the 21^st century need for insulation which improves a property's thermal performance and speeds-up the overall construction process. However, for the performance to match the quality of the product, its installation has to be correct – hopefully first time. 

Visit: http://www.recticelinsulation.co.uk/