The Simplicity of Extending your Home with a SIPs Extension

Whilst traditional building methods i.e., brick and block are historically the ‘go to’ option, a SIPs extension offers huge benefits to homeowners who want an all-round solution that address their particular needs and provide advantages not offered by traditional construction. In fact, in the past two years, we’ve seen the number of people building a SIPs extension with us increase by more than 50%.

Here are just a few of the benefits of a SIPs extension:

There’s no sugar coating it, building an extension is a major upheaval so you want it completed as soon as possible. The good news is that a SIPs extension is super speedy to build and will be completed 30%-40% faster than a brick and block equivalent.

As an example, a typical 4m² x 4m² extension will take one day to fabricate in our factory and around two days to erect the SIPs superstructure of your extension, to weather resistant stage. Depending on the design, installation could be even less.

Based on our current guidelines, we estimate six to eight weeks from your approval/sign off of our drawings, to the shell being delivered to your site. The timeline for your SIPs extensions will always depend on how swift clients’ decisions/approvals are made.

The rapid construction is due to three main factors:

• Off-site manufacturing - Without doubt, one of the main reasons for the speedy construction of SIPs, is the offsite manufacturing process. Each panel is individually precision engineered in a quality-controlled factory setting with apertures and complex design features pre-cut before the kit is delivered to site. This saves time at installation stage, with only minor tweaking to be done, when and if required on site. An added bonus of this means it significantly reduces the amount of follow-on labour required, which as a result, will save on costs.
• Predictable Build Programme - Having a predictable building programme means that you will feel more in control of your project and if you’re not a professional builder, predictability can be very reassuring. The streamline process of off-site manufacturing means that an accurate build programme can be created, allowing for the building site to be fully prepared prior to delivery of the SIPs building system, materials and plant to be ordered and follow-on trades to be scheduled. The predictable schedule means that clients can order their windows and doors as soon as the technical drawings are agreed, mitigating potential delays. 
• No Weather Delays - One thing not even the SIPS@Clays team can control is the Great British weather, so it’s good news that a SIPs extension can be installed come rain or shine. This means there are no weather delays or resultant ‘knock on’ delays to follow-on trades. Once the SIPs extension has been installed and the superstructure is weather resistant, follow on trades can immediately begin, working simultaneously if desired.

It’s often the case when building an extension in residential areas that access is very tight, the neighbouring properties are generally in very close proximity and working space is limited.  This is where the benefits of SIPs surpass traditional construction with offsite manufacturing being the primary factor here (see above). 

Depending on the size of the extension, we can generally transport the factory cut panels in just one delivery, on a suitably sized vehicle for your location and circumstances, with minimal inconvenience and disruption to you and your neighbours. Where access is particularly challenging, we’ve even been known to transport the panels to site using a 4 x 4 and trailer!

If you want to build a highly efficient, sustainable extension with low U-values, superior airtight qualities and reduced thermal bridging, then the inherent qualities of SIPs and especially the Kingspan TEK™ Building System can’t be beaten. 

Depending on the age, condition and insulative properties of the rest of your home, you will see a significant improvement in the ambient temperature in a SIPs extension. By using SIPs and in particular the Kingspan TEK Building System, you could reduce the amount of energy needed in the SIPs extension by up to 50%, relying on the natural efficiency of the fabric of the extension itself.

Just like self building a complete home, there is no need to compromise on design when building a SIPs extension.  Whether it’s single or two storey, as long as a qualified structural engineer has approved the addition to your home, anything is possible. In fact, a SIPs system offers some exciting design opportunities that are not achievable when using brick and block, such as a ‘room in the roof’.

As SIPs roofs are supported by glulam beams rather than roof trusses, they provide the options of a value and space adding ‘room in the roof’, or by leaving the roof open to the eaves you can create impressive double height features. And because space is at a premium when you’re building an extension, the slimmer construction components of SIPs, will always provide a larger floor area than a traditional brick and block extension.

Our design team will work with you, your architect or your contractor to find the best design solution for you, adding value engineering to your plans as standard. More information on these options can be found on our SIPs Brochures, Manuals & Guides page in the Kingspan TEK Building System - Specification Manual

In addition to the many other benefits of building a SIPs extension, the off-site manufacturing means minimal onsite waste is produced, there are fewer deliveries to site than traditional building methods i.e., less construction traffic, and reduced carbon impact on local surroundings.

And because the process is far quicker  and cleaner than a traditional build, the disruption and endless brick dust shower that goes hand in hand with renovating a home, is considerably less when building a SIPs extension – definitely a bonus!

Building a SIPs extension is no harder than building a traditionally built extension… in fact the process itself is very straight forward. 

Whilst the SIPs extension kit is prefabricated off-site,  it is essential that preparatory works, including services, drainage, laying the foundation slab or raft foundation and installation of site equipment, are carried out prior to SIPs delivery. It is also important to have your site as clear of material as possible. This will enable the installation team to have plenty of space to work, allowing them to install the extension quickly and efficiently, without hindrance. 

SIPS@Clays’ installation team will begin by installing a damp proof course (dpc) on the pre laid foundation, with beads of silicone sealant applied to the top surface then a deep treated softwood (C24) soleplate and top plate. The fitting team ensure that the foundation is square and level and pack with levelling ‘shims’ if required, before erection of the panels begins. Accuracy at this stage is key. Watch Clays TV to see how the SIPS@Clays installation team lays the soleplate.

Once the soleplate is complete the SIPs walls are erected. The Kingspan TEK Building system uses a unique panel to panel jointing system which differs for structural and non-structural joints. 

Non-structural panel joints have routed channels along all edges which house an insulated ‘spline’ (or mini SIPs panel) that interlocks each panel. These are secured through the panels OSB/3 facing with nails/screws and expanding urethane sealant between the core of the spline and the panel. This proprietary joint maintains the insulation layer of your SIPs extension.

The structural joint differs slightly, with the panel’s routed channel housing a structural timber, fixed into place as before and sealed with expanding urethane sealant to retain airtightness. 

Once the SIPs structure is complete, it is wrapped in a breathable membrane to protect it from the elements until brickwork or external cladding/finishing is applied.  This stops damp from getting into your panels whilst you wait for ‘knocking through’ and follow-on trades.

Your builder will advise on the equipment required to complete the build, however in order to manoeuvre the wall and roof SIPs panels into position and to lift packed panels to a suitable location at your site, a telehandler or Genie lift (depending on space available) will generally be all that is required for the duration of the SIPs installation. 

We know that every project is individual, so in discussion with our clients, a bespoke installation plan will be drawn up by the SIPS@Clays team which will be dictated by available space at your site and access to it. For example, this may include delivering piecemeal or ‘hand-balling components’, if necessary and safe to do so.  

One of the main differences between a SIPs extension and a traditional extension is that the client needs to do more upfront thinking prior to the panels being fabricated.

This ensures that any technical complexities of your SIPs extension are identified early on, accurate soleplate detail calculated and window and door openings are suitably positioned with relevant tolerances for elements such as overhangs if included. It’s a lot of work at the outset of your project but will ensure value engineering and precise fabrication and it will also save time, hassle and possibly additional costs at the back end of your project. You can read about SIPS@Clays Six Top Tips to help you get started on your SIPs extension (or self build).

As with all types of extension, a qualified architect or surveyor should be consulted prior to any works being undertaken.

For more information on building a SIPs extension either send us your plans via the contact us form or speak to one of our team, who will be more than happy to chat through your SIPs extension with you.