Why self-build with SIPs?

14 May 2020 Kingspan Insulation UK

The process of building your own home is a fantastic opportunity to express your individuality and create a space which is finely tuned to your taste and everyday needs. At the same time, the decision making process can be a little daunting with every choice coming back to you, from the front door to the bathroom taps! Perhaps the single most important choice you can make, however, is the building material. This outer envelope not only defines how your home will look, but also how quickly it can be built, how comfortable it is to live in and how affordable it is to run.

Whilst brick and mortar approaches have long been the default in much of the UK, a growing number of self-builders and contractors are now turning to offsite construction processes. As you might expect, these move much of the construction process away from your plot and into a factory where it can be fabricated with precision and with no risk of rain delays. One of the most popular and well-established offsite approaches in the UK and across Europe are structural insulated panels (SIPs). In this blog, we’ll look at what SIPs are and why they are a popular choice for self-build.

What are SIPs?

SIPs are formed by taking two layers of timber board — typically oriented strand board (OSB) or particle board — and bonding them either side of a rigid insulation core. The resulting panels are strong, lightweight and highly insulated. They can also be easily factory cut to precise shapes and dimensions, creating a kit of panels which can then be quickly erected on site to form the walls and/or roof of the building.

What are the benefits of constructing with SIPS?

Lewes - Kingspan TEK Building System

SIPs offer a number of clear advantages. The offsite fabrication is much more predictable than traditional on-site processes. As the panels are machine cut directly from the agreed CAD drawings, the finished panels are extremely accurate limiting the need for adjustments and waste. They can be fabricated in 4 – 6 weeks from the point that drawings are agreed and are produced to a reliable schedule helping to avoid unexpected delays for their delivery.

Once the foundation is formed, the rest of the envelope can be erected without the need for wet trades such as brick mortar which have to be left to dry. This limits the impact of poor weather on the build programme. The panelised, kit construction also facilitates a fast-track erection programme meaning that the shell for even larger homes can often be built in just two or three weeks. Once the shell is wrapped with a breather membrane and windows and external doors fitted, the building is weathertight, meaning that internal trades can get to work. This helps to greatly condense the construction programme compared with conventional construction projects.

In practice, they provide considerable freedom for designers allowing details such as insulated dormer windows and even barrel roofs to be incorporated. As internal walls are stud-based, it is much simpler and cheaper to adjust the internal layout if you need than with structural internal walls. Whilst the panels themselves are timber faced, this doesn’t mean the home must take on the appearance of a timber building. The flat surface of the panels can support a wide range of exterior facings, including slip brickwork, render and timber. Kingspan TEK SIPs have even had a self-build where the client wanted an industrial feel and opted for Corten steel facing panels.

U-values

The insulation core of the panels can provide high levels of thermal performance out-of-the-box. This is measured through a U-value. Put simply this is a measure of how well a building element (this means a complete floor, wall or roof) can prevent the most common types of heat transfer. Building elements with lower U-values are more effective at preventing heat loss and so better insulated. You can learn a little more about U-values in the video on the left.

Kingspan TEK Building System SIPs are available in 142 mm and 172 mm thicknesses and they can help to achieve whole wall and roof U-values of 0.20 W/m2K and 0.17 W/m2K respectively, without the need for additional insulation. When incorporated into a well-designed home, these values are typically enough to ensure the building is compliant with the Building Regulation/Standard requirements for energy efficiency. Alternatively, if you want to aim for even better performance, you can easily raise this performance further by adding a slim thickness of insulation on the inner or outer face of the panels.

Depending on their jointing system, SIPs can also be used to create buildings which are very airtight and have excellent insulation continuity. For example, our Kingspan TEK SIPs have a routed channel along their long edge. To join them together, we use an insulated cassette which simply slots into the channel. Once an expanding urethane sealant is applied this joint works together with the OSB/3 facing of the TEK panels to prevent air-leakage. When used in combination with a mechanical ventilation and heat recovery (MVHR) system – which uses the warmth from exhaust air to heat incoming air – this can create a comfortable and quiet environment which has low energy bills and a small carbon footprint.

To ensure Kingspan TEK projects are completed to the highest standards, we work with a network of approved and carefully audited Kingspan TEK Delivery Partners who understand the system’s capabilities and can ensure projects take full advantage of them.

What to expect when working with a Kingspan TEK Delivery Partner

The Kingspan TEK Building System

Our delivery partner network offers flexible packages to meet your particular needs, from simply designing and erecting the building shell, to a full turn-key package including heating and ventilation, windows, doors and staircases. 

They work with your designer or architect to turn initial planning drawings into a complete CAD drawing and provide a fairly comprehensive quote including the type of plant needed, extent of scaffolding and any additional structural elements that may be required such as glulam roof beams.

Once the design is agreed, the Delivery Partner will work with your building contractor to provide the engineering calculations and line and point loads for your foundation, helping to ensure this work is fully completed before the panels are delivered to site. Whilst this work is ongoing, the Delivery Partner will get to work at their own sites cutting the panels to size on a giant CNC cutting machine. They are then labelled up to ensure a fast and accurate installation.

The Delivery Partner will stay in touch throughout the production process, clearly communicating the expected start date. Once the panels are delivered to site, the installation itself can be completed very quickly. The Delivery Partner installers will first fix a treated sole plate to the foundation – creating the outline of the building footprint. Urethane foam is applied to the soleplate and the SIPs are lifted– either by hand or with a lightweight lifting vehicle – slotted in place and secured with mechanical fixings. Adjoining panels are slotted together using the cassette joint (again with urethane foam applied to joints). Once the external ground floor walls are erected, timber battens are fitted to the top of the panels and the internal walls can be erected.

Next the floor joists can be hung from the panels and an OSB or particleboard flooring installed over the top. A bottom plate is then fitted around the perimeter of the floor, and the second-floor panels lifted and slotted into place.

For pitched roofs, purlins are fitted into pre-cut slots at the top of the wall panels. The SIP roof panels can then be lifted and fitted. TEK panels can also be used in flat roof configurations and have even been used to create barrel roofs.

The Delivery Partners will also fully wrap the building shell with a breather membrane and prepare the pre-cut opening for doors, windows and rooflights. They can either carry out installation of these features and the outer cladding, or provide guidance to the building team to ensure these features are accurately installed and sealed to limit air leakage and thermal bridges. Before handover, they will carry out a full check of the building to ensure your complete satisfaction.

Built to last

In addition to these benefits, and for added peace of mind, the Kingspan TEK Building System is recognised by major building warranty providers and holds BBA Certification No. 02/S029 and is covered by ETA Certification No. ETA-11/0466.

All of this means that by selecting Kingspan TEK, you can have confidence that you are getting your self-build off to the best possible start.

Kingspan Insulation Ltd

Pembridge

Leominster

Herefordshire

HR6 9LA

General enquiries: 01544 388 601

Technical advice: 01544 387 382