SIPs systems offer an extremely low energy and eco-friendly construction method that’s also incredibly strong and quick to build. Matt Banks of SIPs Eco Panels explains more about the options available

As we move into an era of low energy zero carbon construction, the inherent energy efficient, airtight nature of structural insulated panels has attracted self-builders across the world. SIPs (Structural Insulated Panels) now account for around 10 per cent of all self-build construction and this is increasing rapidly. The average SIPs home benefits from a 50 per cent decrease in energy consumption and drastically reduced CO2 emissions. In fact, manufacturing of SIPs uses 80 per cent less energy than traditional building methods, making it a popular green building method.

One of the major benefits of structural insulated panels over traditional masonry or timber frame construction is speed. A typical SIPs three-bedroom home can be installed on site in a period of five to seven days, resulting in huge savings on build programme and labour costs. The installation of a SIPs structure also requires significantly less manpower and site supervision with the majority of installation teams being made up of four operatives.

Offsite fabrication removes the risk factors involved in traditional onsite construction. SIPs are precision manufactured in controlled factory conditions using CNC machine cutting with extreme accuracy and minimal waste. Once design drawings are agreed, a SIPs superstructure can be fabricated in four to six weeks and delivered straight to site for immediate installation.

SIPs houses can be built with zero reliance on weather conditions, for minimal disruption to the critical path. The building envelope can be installed in most weather conditions without the need for wet trades like brick and block construction, which needs to be left to dry and is heavily impacted by poor weather. Once the SIPs structure is up, it is wrapped in a breather membrane, leaving it wind and watertight and ready for internal and external trades to get to work without delay. This again significantly reduces the overall construction programme and is up to three times faster than other traditional construction methods.

A more innovative approach to roof construction results in increased usable roof space. SIPs roof panels are structural and arrive pre-cut and fully insulated with no need for roof trusses. The elimination of trusses can result in a double height floor to ceiling. With the extra space, you can leave a large open ceiling space either for storage or install partitions to add extra rooms, or opt for a vaulted ceiling. Dormers or skylights can be very easily added at little extra cost, allowing for design flexibility to make the most of the system.

CHOOSING THE RIGHT TYPE OF SIPS SYSTEM FOR YOUR PROJECT

There are two main types of SIPs, the difference being the insulation used:

• EPS (Expanded Polystyrene) – 100 per cent recyclable and extremely durable. EPS insulation has zero ODP (Ozone Depletion Potential) and GWP (Global Warming Potential).
• Injected fibre-free rigid urethane core.

Both systems consist of an insulating foam core sandwiched between two structural facings typically OSB3 (oriented strand board). EPS has been used in the construction industry for decades, it’s lighter in weight and easy to install. EPS insulation is non-toxic and chemically inert and does not degrade or delaminate over time. Although you get a slightly thinner wall with rigid urethane SIPs, its thermal performance can be reduced over the first three years of use. SIPs panels are extremely strong, and surrounded by high quality structural grade timber.

Where structural requirements allow, manufacturers will use a purpose-built joining system, in the form of an insulated SIPs spline connecting the panels. This SIPs joining spline provides continuous insulation and high levels of airtightness compared to a standard timber frame kit. Traditional timber frame for example, has a much lower thermal resistance and has been recorded as losing more than 30 per cent of a household’s energy.

Beyond the building envelope, some SIPs manufacturers will only supply all internal walls as studwork. However, for increased thermal and acoustic performance, other manufacturers can also supply a thinner SIPs internal wall panel in place of studwork, giving a greater flexibility of choice for self-builders.

Whichever system you choose, make sure the SIPs manufacturer is accredited with UKAS recognised certification and are Gold Assure Members of the Structural Timber Association. These manufacturers will be regularly audited by independent third party organisations to ensure standards of excellence are maintained.

COST EFFECTIVE

When comparing structural systems, it’s clearly important to look at the overall construction costs of the project. While SIPs can appear a more expensive form of construction initially, there are major time and overall cost savings across the entire build programme. Unlike timber frame or masonry systems that require additional follow on trades to fit insulation and prepare the structure to be ready for first fit electrics, plumping and dry linings, a SIPs package is ready to go. With a SIPs system, you are getting a fully insulated structural shell that does not require any follow-on trades, labour or additional materials.

As a SIPs build can be completed up to three times faster than other structural systems, overall construction costs can be reduced. This time saving results in reduced scaffolding costs, lower plant hire costs, savings on labour, site management, accommodation and a huge reduction in site waste. This speed of build and the reduction of risk brought about by the offsite manufacturing process results in fewer delays, an efficient build, and fewer unexpected costs.

Structural Insulated Panels (SIPs) are the future of building in the UK, and will continue to change the landscape of the construction industry for years to come.

Matt Banks is commercial director at SIPs Eco Panels