SIPS home extensions

---

In an era where energy efficiency, speed of construction, and sustainability are more critical than ever, homeowners across the UK are turning to modern methods of construction to future-proof their properties. Among these, SIPs (structural insulated panels) stand out as one of the most innovative and versatile solutions on the market today.

Whether you’re planning a kitchen extension, a garden room, or a complete annexe, SIPs offer a faster, stronger, and more eco-friendly alternative to traditional brick-and-block building methods. This guide is your complete resource for understanding SIPs extensions—from what they are to how they’re built and why they’re quickly becoming the preferred option for forward-thinking homeowners.

Structural Insulated Panels, commonly referred to as SIPs, are a high-performance building system used for walls, roofs, and floors in residential and commercial construction. Each panel consists of an insulating foam core sandwiched between two structural facings—typically Oriented Strand Board (OSB).

SIPs are pre-engineered and manufactured off-site, which makes them ideal for fast-track building projects. Once delivered to the site, they are assembled like a jigsaw, significantly reducing labour and build time.

Core materials include:

• Expanded Polystyrene (EPS)
   

The result is a lightweight yet extremely strong system that provides superior insulation, airtightness, and structural integrity.

SIPs are revolutionising the UK extension market—and for good reason. Below are some of the most compelling advantages they offer:

SIPs deliver excellent thermal performance thanks to their continuous insulation core. With minimal thermal bridging and superior airtightness, SIPs extensions can achieve U-values as low as 0.10 W/m²K, depending on the specification.

This means lower heating bills, greater year-round comfort, and enhanced compliance with Part L of the Building Regulations.

Time is money—especially in construction. SIPs systems can be erected in a matter of days, not weeks. This rapid build time reduces site disruption, labour costs, and delays caused by weather or traditional trades.

SIPs are incredibly strong relative to their weight. Once assembled, they form a rigid, monolithic structure capable of withstanding heavy loads and extreme weather conditions. They meet or exceed UK structural standards and are suitable for multi-storey applications.

With sustainability becoming a cornerstone of modern construction, SIPs are an environmentally responsible choice. They use less timber than traditional framing methods and drastically reduce energy consumption over a building's lifetime. Many SIPs products are PEFC or FSC certified, ensuring responsible sourcing.

While the upfront costs may be slightly higher than traditional builds, SIPs pay for themselves through:

• Reduced heating and cooling bills
   
• Shorter construction timeframes
   
• Lower labour costs
   
• Less material waste on site
   

One of the standout advantages of structural insulated panels (SIPs) is their remarkable design flexibility. Whether you're envisioning a minimalist garden office, a spacious kitchen extension, or a multi-room annexe, SIPs can be tailored to meet diverse architectural styles and functional requirements.

ETZ Group, a prominent UK-based company, offers a range of SIP panel home extension kits that epitomize cutting-edge design and efficiency. Their kits are engineered for optimal thermal performance and structural integrity, enabling rapid installation and seamless integration with existing properties .

Similarly, SIPS Kits specializes in self-build SIPs kits, providing customized solutions for home extensions, garden rooms, and annexes. Their panels come in various sizes, ranging from 98mm to 242mm, to achieve and exceed the U-values needed for building control.

Understanding the construction process of SIPs extensions can help homeowners appreciate the efficiency and precision involved:

1. Design and Planning: Collaborate with your chosen provider to finalize the design, ensuring it meets your aesthetic preferences and functional needs.
    
2. Manufacturing: The SIPs are prefabricated off-site in controlled environments, ensuring high quality and reducing on-site waste.
    
3. Delivery and Assembly: Once manufactured, the panels are delivered to your site, ready for assembly. Companies like ETZ Group provide detailed instructions and support, making the process straightforward.
    
4. Finishing Touches: After the structural assembly, you can proceed with internal finishes, electrical installations, and other customizations.
    

This streamlined process not only reduces construction time but also minimizes disruptions to your daily life.

When considering a SIPs extension in England, it's essential to be aware of local regulations and planning permissions.

• Permitted Development Rights: Some extensions may fall under permitted development, meaning they don't require formal planning permission. However, specific criteria must be met regarding size, height, and location.
   
• Building Regulations: Regardless of planning permission, all extensions must comply with building regulations to ensure safety and energy efficiency.
   
• Consultation: It's advisable to consult with your local planning authority or a professional advisor to understand the specific requirements for your project.
   

Companies like ETZ Group and SIPS Kits often assist clients in navigating these regulations, ensuring a smooth approval process.

SIPs extensions are incredibly versatile, making them suitable for a wide variety of residential projects. Whether you’re a homeowner looking to enhance your living space or a property developer aiming to maximise value, SIPs can be adapted to suit almost any purpose.

• Kitchen Extensions
  Open-plan kitchens and dining spaces are in high demand, and SIPs are perfect for creating these large, open areas quickly and efficiently.
   
• Garden Rooms
  Detached offices, studios, or relaxation zones constructed using SIPs benefit from thermal efficiency and noise insulation—ideal for year-round use.
   
• Home Offices and Studios
  As remote working becomes more permanent, SIPs-built home offices offer a quiet, professional space separate from the main house.
   
• Granny Annexes and Guest Accommodation
  SIPs are a great solution for adding independent living quarters to your property, complete with plumbing, heating, and full insulation.
   
• Loft Conversions and Garage Extensions
  Lightweight yet strong, SIPs can be used to create additional storeys or over-garage rooms without overloading existing structures.
   

ETZ Group provide tailored solutions for all of the above, offering pre-designed kits or fully bespoke services depending on the scope of your project.

Cost is always a central consideration in any building project. While SIPs might seem like a premium product at first glance, their value becomes increasingly clear when you look at the full picture.

The initial cost of a SIPs extension typically includes:

• Design and Engineering
   
• SIPs Manufacture
   
• Delivery and Assembly
   
• Internal Fit-Out (e.g., electrics, plastering, finishes)
   

Estimated costs for a SIPs extension in the UK (as of 2025):

Extension Type Size (approx.) Cost Range (Turnkey) Small Garden Office10–15 m² £15,000–£25,000 Rear House Extension 20–30 m² £35,000–£60,000 Granny Annexe30–50 m² £50,000–£90,000 

Note: These are ballpark figures. For accuracy, always request a detailed quote from your supplier.

SIPS Kits offers competitively priced DIY kits, starting from around £445 per square metre, excluding delivery and VAT. These are ideal for self-builders with some experience in construction.

ETZ Group provides fully managed solutions, which include design, groundworks, SIPs kit installation, and finishing—giving clients a hassle-free experience with transparent pricing.

While SIPs construction may carry a slightly higher initial cost than traditional blockwork or timber frame, the long-term benefits quickly justify the investment:

SIPs provide excellent thermal performance, significantly reducing heating and cooling costs over time. Many SIPs extensions meet or exceed Passivhaus energy standards.

Fewer days on-site means lower labour costs and earlier project completion. For businesses or landlords, this translates to quicker returns or rental readiness.

SIPs are durable, stable, and resistant to warping, sagging, or settling. Their low-maintenance nature saves costs on repairs and adjustments in the years ahead.

A high-performance SIPs extension adds more than just square footage—it contributes to your home’s energy rating, desirability, and resale potential.

Let’s say you’re building a 25m² kitchen extension.

Aspect Traditional Build Time 10–12 weeks

SIPs Build Estimated Build 3–4 weeks. 

Heating Cost Savings (pa) Baseline Up to £400 Labour Intensity High Moderate Air Tightness / Insulation Moderate High 

Over 10 years, a SIPs extension could save £4,000–£6,000 in energy costs alone—not to mention the time and stress saved during construction.

In today’s world, building isn’t just about adding space—it’s about creating a smarter, more sustainable way of living. SIPs extensions are a future-ready solution that aligns with the UK’s growing focus on energy efficiency, carbon reduction, and modern living standards.

• Energy Performance: Meet and exceed new energy regulations with ease.
   
• Smart Home Integration: SIPs create airtight envelopes ideal for heat recovery, smart HVAC systems, and smart lighting.
   
• Low-Carbon Footprint: SIPs are manufactured with less material waste and higher insulation standards, making them a better long-term environmental investment.
   
• Increased Resale Appeal: Buyers are increasingly prioritising eco-conscious features—SIPs-built homes and extensions stand out in competitive markets.
   

As climate regulations tighten and energy costs rise, SIPs provide long-term peace of mind for homeowners who want to invest wisely today and benefit for decades to come.

Not all SIPs systems—or providers—are created equal. When selecting a company to deliver your SIPs extension, look for:

• Proven Experience: Look for a track record of successful builds, client testimonials, and detailed case studies.
   
• In-House Design Expertise: Choose a team that can help you optimise the design for your lifestyle and site.
   
• Technical Support: Especially for self-build kits, make sure full installation guidance is provided.
   
• Compliance Knowledge: Providers should guide you through Building Regulations, U-values, and structural calculations.
   

• ETZ Group: A trusted name in the SIPs construction space, offering end-to-end solutions across home extensions, garden rooms, and annexes. Their professional approach and attention to detail ensure every project is delivered to the highest standard.
  Visit: www.etzgroup.co.uk
   
• SIPS Kits: Ideal for hands-on homeowners and self-builders, SIPS Kits provides customisable, precision-manufactured kits that can be adapted to virtually any layout or design.
  Explore: www.sipskits.co.uk
   

Whether you’re expanding your home to suit a growing family, building a flexible workspace, or investing in energy-efficient living, SIPs extensions offer one of the most forward-thinking building methods available today.

Faster to build, cheaper to run, and better for the planet—SIPs are the smart choice for modern homeowners.

Ready to explore your SIPs extension?

Whether you want a fully managed build or a high-quality self-build kit, ETZ Group and SIPS Kits are here to help bring your vision to life.

Get started today:

• Discover pre-designed kits or request a bespoke quote at www.etzgroup.co.uk
   
• Browse self-build options at www.sipskits.co.uk