Many people are opting to improve rather than move when looking to add more living space. By building an extension, garden room or annex to an existing property, homeowners can create additional space and boost the value of their home.

Traditionally, people have opted to use a masonry or ‘brick and block’ method where insulation is then added to the cavities, the demand for Structural Insulated Panels (SIPs) has rocketed as homeowners are asking for better insulation so they can reduce their energy bills. SIPs provide a wide range of benefits as a construction method, including faster build times, durability, and thermal efficiency. Below, we look at some of the reasons why SIPs are becoming increasingly popular and what factors you should consider when using SIPs.
 
Increased thermal efficiency

With household bills expected to quadruple in less than a year and temperatures fluctuating up to 40 degrees this year, due to climate change, now is the perfect time to consider SIPs if you’re looking to extend or build a garden room or annex.

Building with SIPs provides a high level of thermal efficiency and extreme airtightness, which results in reduced days that your building needs heating or cooling, significantly reducing energy bills. Additionally, the jointing system of SIP structures offers extreme airtightness which results in cooler homes during the warmer periods.

Costs of building with SIPs 

One of the factors when considering making improvements to an existing space is upfront costs, so how much does it cost to build an extension, garden room or annex with SIPs?

When looking at costs, there are multiple factors that can affect the cost of building with SIPs, these include;

• Quality of SIPs – it is important to choose a SIP that is high-quality and provides a lower U-value. SIPs buildings use up to 50% less energy than other building materials. Ensuring the SIP is high-quality will reduce long-term costs as the building will be more energy efficient.
  
  When comparing the quality of a SIP, some important factors to be considered are the manufacturing process of the insulation and relevant certifications. In relation to the manufacturing process, Polyurethane insulation (PUR) provides a higher R-value as the insulation is auto-bonded to the panel, this method is stronger than the glued EPS alternative. This is an important factor as using a PUR SIP rather than an EPS SIP can prevent delamination issues.
  
  Certification is another factor to consider when building with SIPs to ensure they are high-quality. BBA Certified products are extensively tested for Structural, Acoustic and Thermal properties, including Fire Resistance which are important factors when selecting a material for your build. Many homeowners find that they cannot secure finance on a SIP that doesn’t have a BBA certificate.
  
  
• The size of the building – the larger the building, the more panels will be required. However, SIPs create more internal space as the required u values can often be achieved with the SIP alone, without the need for additional layers of insulation.
  
  
• Follow-on trades – more complex projects will require an increased number of follow-on trades, once the initial building superstructure is in place and can be made weather-tight quickly. Using SIPs, which are prefabricated in a controlled manufacturing environment means that follow-on trades can be onsite faster, with fewer delays.

Although SIPs have a slightly higher upfront cost in comparison to traditional masonry materials, the construction time is 60% faster than other construction methods due to the SIPs being cut to size. This will reduce both build time and costs which can make the overall project costs comparable. 

FAQs

How long will my extension, garden room or annex last?

SIPs are a very durable construction material and are typically covered by a warranty of up to 60 years (two mortgage periods), although SIP builds last much longer in reality.

Can I build my own SIPs extension or garden room?

Whilst SIPs projects can be straightforward, we recommend contacting a professional tradesperson to carry out the work. We have professional tradespeople we can recommend should you require more information please contact us here.
 

What finishes can I have on my SIPs extension, garden room or annex?

SIPs buildings can have the same external finish as any other construction method, such as render, cladding or brick slip.
 

How big can my SIP extension or building be?

SIPs can create spaces as big or as small as required. When building an extension, you will more than likely need building regulations approval to ensure they meet the minimum technical standards. These standards mean you will need to consider;

• Energy performance - U Values to comply with Building Regulations Part L (updated earlier this year)
• Structural Integrity
• Protection against falls and unsafe walls
• Electric and gas safety
• Fire protection

More information on building regulations for extensions can be found here: https://www.homebuilding.co.uk/advice/building-regulations-for-extensions

If you’re considering extending or building a garden room or annex and would like to find out more, please contact our team and we can put you in touch with our install partners.