CPD articles

CPD: PIR insulation panels

3 April 2017 | By Peter Wilcox

As an alternative for mineral wool insulation in masonry wall cavities, polyisocyanurate panels offer ease of installation, water ingress protection and excellent thermal properties, explains Peter Wilcox.

The energy-deficiency of the UK’s ageing housing stock was once again thrown into sharp focus with the publication in February of a report by the UK Green Building Council.

The Building Places that Work for Everyone policy paper states that 25 million homes across the country will not meet required insulation standards by 2050 — a significant year for the government, as by then it has to have met its legally-binding pledge to cut UK greenhouse gas emissions by at least 80% from the 1990 baseline. An enormous task, particularly as poorly-insulated homes account for 25% of emissions released in the UK.

The UK Green Building Council, which produced the report in conjunction with the construction industry, has urged the government to impose a countrywide programme of home renovation to increase energy-efficiency and improve the health, wealth and wellbeing of occupants. However, sceptics have already raised doubts over the potential success of such a scheme, citing the failure of the Green Deal.

Launched in 2013, the Green Deal offered loans to homeowners embarking on domestic energy-saving measures. It was scrapped two years later after figures revealed only 14,000 householders took up the option. The £50m government loan outlay fell a long way short of its £1.1bn forecast, with high interest rates for loans given as a reason for the Green Deal’s ultimate collapse.

There can be no doubt the thermal performance of UK buildings needs to be addressed urgently. Even though the 2050 deadline might be viewed by some as “an issue for tomorrow”, the spiritual and fiscal comfort of today’s homeowner/occupiers can be vastly improved with an energy-efficient interior. Insulation manufacturers are developing ever-inventive solutions in an attempt to put a thermal seal on the building envelope.

Insulation with a difference

Eurowall + is, an innovative, precision-cut, full-fill cavity insulation board produced by polyisocyanurate (PIR) manufacturer Recticel Insulation. In essence, it changes the way a wall works without changing the way it is constructed. It features a tongue-and-groove joint on the board’s four sides to ensure a tight, secure lock and guarantees increased protection against wind-driven rain.

Another innovative facet is its size. While many rigid full-fill products are 97mm or thicker for a designed cavity width of 100mm, Eurowall + offers a 90mm insulation board to achieve similar thermal performance while avoiding impeding conventional bricklaying techniques. Recording lower U-values while maintaining traditional cavity widths means existing house designs do not have to be adapted.

Recticel’s reputation for quality technical knowledge is maintained by its support team, who are able to advise on the PIR insulation product that is most suited to your project. Ensuring that specification complies with the latest Building Regulations and other carbon reduction programmes as well as providing condensation risk analyses, U-Value calculations and advice on installation best practices.

Recticel PIR rigid insulation products are composed of a polyisocyanurate foam core with a closed cell structure. These products deliver a high thermal performance, contributing to a substantial energy saving in building projects and in turn increasing the comfort of the end user.

As well as offering excellent thermal properties, Eurowall + offers a cost-effective alternative to other forms of cavity wall insulation. The boards save on material costs, as items such as wall ties and lintels do not have to be increased in size to suit larger cavities.

Comprehensive supporting details, such as thermal bridging calculations help to ensure that junctions are built correctly and the improved performance is accurately accounted for in Standard Assessment Procedure (SAP) energy calculations – a Building Regulations requirement for all new houses, conversions and some extensions – as part of a “fabric first” approach.

Home reassurance

By helping to achieve lower U-values in walls, Eurowall + contributes to reduced heat loss and better domestic energy efficiency, creating the ultimate benefit for homeowners: lower energy bills through reduced heating use. Eurowall + can help new homes to meet and exceed the requirements of Building Regulations Part L 2013 (England) and Part L 2014 (Wales) as part of the complete specification, reassuring the prospective homeowner that their future house is comfortable and energy-efficient.

Eurowall + was designed with the builder, as well as the end user, in mind. It addresses a common complaint from onsite trades that rigid full-fill insulation boards impede conventional bricklaying techniques. With a nominal 10mm air space between insulation and outer brick leaf, there is room for bricklayers to work as normal while the external wall achieves  thermal performance targets.

The boards are lightweight and easy to handle and cut, which assists in the delivery of safe onsite working practices. Eurowall + provides high levels of thermal performance in the wall and at crucial junction details, as well as excellent resistance to external moisture, resulting in a healthy and comfortable internal environment as part of the complete building specification.

Building Regulations - England Part L 2013

U-values are part of wider assessment criteria to meet the requirements of Part L as a whole. Other factors taken into account include: airtightness, door and window U-values, the heating system, and thermal bridging. “Limiting U-values” are the worst acceptable level of performance, but designing to these values is unlikely to result in compliance. The “notional building specification” is a recipe approach that will ensure compliance if all standards are met.

In-situ, Eurowall + helps reduce a home’s carbon footprint by cutting energy usage, its production is carried out with the highest environmental considerations. It is manufactured using a blowing agent with zero ozone depletion potential (ODP) and low global warming potential (GWP).

Wall ties do not need to be increased in size to suit larger cavities

Therefore its specification displays a commitment to minimising energy consumption, harmful CO2 emissions and impact on the environment. After eight months, a Eurowall + board saves more energy than was used in its production.

The tongue-and-groove joint negates the need for taping the boards’ joints — a major cost and time-affective benefit which sets it apart from similar products. Compared to other boards, Eurowall + is relatively straightforward to use. It’s flat and, when installed, the tongue-and-groove joints lock in tightly. The boards are easy to cut, and fit tightly around the wall ties.

Space creator 

Installing full-fill rigid PIR board in wall cavities, rather than mineral wool, represents a change for bricklayers. Mineral wool products are tested by the British Board of Agrément (BBA) to the same rigorous standards. In normal conditions and installed correctly it should perform well.

The main benefit of PIR over mineral wool, however, is the reduction of wall thickness.For mineral wool to attain the same level of thermal performance as Eurowall + board, it’s estimated 150mm-thick 0.32Wm2K insulation would need to be installed, resulting in an accordant increase in the cavity wall size. And once the cavity width increases, wall-tie lengths have to be lengthened and window and door lintels expanded – the whole building process becomes more costly.

With developers looking to fit as many homes onto allocated plots as possible, maintaining a 100mm cavity in new buildings means room sizes can be bigger. Eurowall + 90mm board not only ensures a 0.18 U-value in a 100mm cavity, the 10mm air gap makes for a less inconvenient fit for bricklayers when it comes to installing it. Therefore, Eurowall + maximises space while minimising cost for house builders.

One of the main threats to cavity wall masonry construction is moisture ingress from wind-driven rain. The Eurowall + tongue-and-groove joint offers increased protection against damp caused by inclement elements. After all, prevention is better than cure, and once damp takes hold of a building, the expense and inconvenience involved in its removal can be significant.

Eurowall + achieved British Board of Agrément (BBA) certification in October 2015 (Certificate number (02/3908). It is also Local Authority Building Control (LABC) approved – no: EWW620. Its price per sq m is as follows: 75mm, £13.81; 90mm, £16.38; 115mm, £20.52; 140mm, £24.41.

Peter Wilcox is development manager at Recticel Insulation

Product fits the bill at Hampshire housing

Eurowall + was the product of choice for two large-scale housing developments that required cavity insulation offering excellent thermal capabilities as well as long-term protection against damp.

The multi-million pound developments at Hedge End in Southampton, and Ludgershall in Andover, contain nearly 300 plots as part of a mixed social and private property scheme undertaken by Foreman Homes. To maximise the long-term thermal performance of each home, a reduced thickness, full-fill insulation board which allowed for lower U-values, was required. Eurowall + met the brief.

In total, 15,000 sq m of Eurowall + insulation board was installed across the two housing developments, which feature properties of two to five bedrooms. The panels’ lightweight, easy-handling capabilities made for a simpler and more rapid application between the brickwork and internal blockwork of each building, than traditional glass or mineral insulation material — without compromising thermal performance.

“For our onsite teams, the rigid foam board was a lot easier to handle than traditional forms of cavity insulation.”

Gary Hunt, Foreman Homes

For Foreman Homes, it meant reduced installation times and onsite construction costs, while the eventual occupiers will inhabit an energy-efficient home which maximises comfort and reduces annual fuel costs. Eurowall + also provides excellent resistance to external moisture, minimising the potential for long-term damp issues.

Explaining the decision to specify Eurowall + for both blue-chip housing projects, Gary Hunt, senior buyer at Foreman Homes, said: “Its high insulation values made Eurowall + the obvious choice for the developments. We not only wanted to achieve NHBC standards in terms of each property’s thermal performance, our ambition was to ensure each home maintained its energy-efficiency for many years to come. Eurowall + will go a long way to helping secure that. For our onsite teams, the rigid foam board was a lot easier to handle than traditional forms of cavity insulation.”

The two-year works programme for both housing developments is expected to be completed in October 2017. The proven thermal capabilities of Eurowall + will help uphold each property’s status as an energy-efficient asset for its owner and the environment.


Please confirm that the pir insulation requires to be broken on party walls with a Rockwool fire barrier, common issue on site the assumption that the pir is a fire barrier

ERIC TUDOR, 3 August 2017

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