October 09

Over the last few years the external wall insulation industry has significantly increased its share of the new build and refurbishment market – especially with regards to a wide range of educational buildings, where it has been specified to meet more stringent Building Regulations.
In order to respond to the climate change challenge, the Government has introduced a programme of legislation to meet the UK’s carbon saving commitments. One of the key targets is to achieve zero carbon construction for homes by 2016, with all non-domestic buildings to be zero carbon from 2019 (with earlier targets for schools and public buildings).
It is in working towards these targets that the external wall insulation industry is well poised to be at the forefront of the construction. Placing insulation on the external surface of the building, protected by weatherproofing, is now seen as a prime solution in meeting climate change objectives.
Architects and forward looking builders are leading the construction industry in producing sustainable energy saving educational buildings. In an increasing number of cases, external wall insulation systems using insulated render are now regarded as the solution to meet the most demanding energy efficiency requirements. This is because external wall insulation can achieve much higher wall insulation values than other insulation methods.
Whilst the new build market for the process may be somewhat quieter than in recent years, the demand in the refurbishment/re-build of schools has increased. For example, in facing a decision to demolish outdated, but structurally sound buildings, or to re-style them to meet modern thermal insulation and design requirements, specifiers are now turning towards external wall insulation as a solution to increasing energy efficiency standards.
Insulated render systems have been used successfully on a range of supporting materials in concrete and steel framed structures on schools, universities and similar educational buildings. These buildings have been insured for up to 20 years and have an assessed life of at least 30 years – which may be extended to 60 years with a maintenance regime.
External wall insulation is applied to the outside of the building for insulation, weatherproofing, and appearance purposes. The original look of the building can be reinstated or can be updated with a real brick finish. Today’s look couples brick finish on the lower level with render for the first floor. A really modern architect-designed look can be achieved by using different colours and finishes. Or Georgian, Victorian, Edwardian and other modern designs can be replicated.
Insulated renders have been used to envelope modern construction methods to meet current and future standards and to enable imaginative aesthetic design to use the curved surfaces currently demanded.
The wide range of coloured renders – very often in different colour bands separated by painted tape boards – can provide striking colour finishes and can be used to interesting effect to give a modern aesthetic result.
Another factor in selecting an external wall insulation system is the speed of application, which causes as little disruption to the community as possible. Additionally, educational buildings often have the need for high performance render, resistant to dirt, low maintenance and with insulation for sound proofing, as well as excellent thermal performance.
The now pressing need for sustainability of buildings, as well as other resources, is creating a new demand for solutions to reducing wastage and pollution. Insulated render is the solution that puts the insulation in the optimum place within the building; that allows both old and new buildings to operate effectively and sustainably; and that lends itself to exciting, imaginative and radical designs and solutions for all types and conditions of buildings.
Timber frame construction is a fast building method which provides a lightweight structure. Insulated render systems are applied directly onto the sheathing boards of the timber framed construction. Systems can be designed with drained and ventilated cavities, to meet the requirements of NHBC. Designers are now able to significantly increase thermal and acoustic performance levels and achieve lowest U-values. This method of construction enables large structures to be erected, made watertight, and finished externally at high speed. It lends itself to off-site, partially factory construction, which helps to meet the Egan Report requirements.
Steel stud with external weather grade cementitious board, insulation and render is becoming widely used in the new build field, particularly with high rise commercial buildings. The steel element eliminates the need for bricklayers/blockwork, which is governed by the availability of suitable tradesmen and weather. Whereas steel studwork can be pre-fabricated off-site ahead of it being required and quickly fixed in position using semi-skilled labour, immediately the structure is ready to receive it.
Once the cementitious board is fixed and the joints sealed, the structure is watertight and internal trades can commence early, whilst the fixing of insulation and render externally follows, thus speeding up the whole building process and reducing overall programme costs.
As a secondary precaution against water ingress, a breather membrane can be accommodated between the cementitious board and insulation.
This means of construction is not only quicker, but can be just as inexpensive, if not less so, than traditional blockwork. In addition, it is much lighter, hence it creates further savings with regard to size/cost of the main frame of the structure, plus the foundations themselves.
Similarly, additional insulation can be increased between the steel studs to further improve the U-value, merely to increase the density to achieve better acoustic requirements.
In association with the Steel Construction Institute the Association has been instrumental in producing a guide, Insulated Render Systems Used with Light Steel Framing, to provide design guidance and good practice recommendations. This publication is available from INCA at a cost of £35 (payment to be sent with order).
The Insulated Render and Cladding Association (INCA) points out that it makes good sense for buildings across the board to be treated with insulated render – not just those with solid walls. Latest government figures show that external wall insulation is the most effective insulation process – twice to thrice more effective than cavity wall insulation in terms of heat and money saving ability.
One of INCA’s main objectives is to help increase the size of the UK insulated render market by 75% by 2010 from 2Mm2 in 2006 to 3.5Mm2. It aims to increase membership of INCA so that by 2010, the organisation represents all system designers, 80% of specialist contractors, and as associate members, the principle component suppliers. Through the INCA brand it hopes to develop the image and position of the industry.
A typical ‘state of the art’ educational building, where insulated render was specified, is the New Fairfield School, Horfield in Bristol. This is a horseshoe shaped building, rising to a maximum height of six storeys, with a central atrium as the school assembly hall. External balconies provide access to classrooms and allow pupils to study and congregate outside. This type of design has been used successfully in Holland, where it was found to improve the behaviour of the children, giving them a more adult environment in which to study.
Cowlin and Bristol City Council required a high level of insulation to meet the U-value of below 0.2W/m2K – and to preserve the environment: 100 mm thick mineral fibre insulation boards were used on a steel-frame building. The external cladding is mainly self-coloured rendering, with a feature facing brick plinth to the ground floor, with timber panelling.

By Gillian Allder, Chairman, Insulated Render and Cladding Association