Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm)

Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm)

Brand Forest Xtend

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£12,619.99

Free delivery

3 offers at 3 retailers

Listed since 18 May 2026

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Description

The Forest Xtend 4.0+ is a modern SIP garden room designed to work with your busy lifestyle. This versatile garden building is perfect for use as a garden office but also makes an excellent year-round family space or hobby room. Including UPVC double doors and opening windows, the Xtend 4.0+ is an industry-leading garden room, fully insulated due to its SIP panel construction, making it a pleasurable space to work from home throughout the seasons. Revolutionary SIP Garden Room Construction As an economic alternative to a home extension, this premium garden room is constructed from pre-cut, modular structural insulated panels (SIPs). Many new homes are now being built this way as SIPs offer ultimate insulation, are energy efficient and are robust. Unlike many other brands who offer just insulated walls, the Xtend range features SIP construction for the roof and floor too. The result is a SIP garden room that is fully insulated from top-to-bottom. The incredible level of insulation also ensures that the garden room will not be subject to damp, will be cool in summer, and will remain warm in winter. SIP Panel Walls with Internal and External Cladding Each wall SIP consists of 97mm insulation sandwiched between two sheets of OSB (oriented strand board). The SIPs are completed and further insulated by both external and internal cladding. The internal cladding is MDF with a vertical beaded profile for a sophisticated appearance. It is primed ready for painting. The external cladding is high-quality, kiln-dried 15mm tongue and groove timber. As well as offering a stylish finish, tongue and groove is known for its weathertight structure. This combination of SIP, cladding and the cavities between gives the walls an incredible overall thickness of 177mm. Floor and Roof Built from SIPs For increased insulation, the 108mm floor and 122mm pent-style roof are both built from SIPs too. The floor is left uncovered, so can be finished with carpet, laminate or other flooring according to personal taste. The interior of the roof is finished with pre-primed interior cladding ready for painting. EPDM Rubber Roofing Outside, the roof features a market-leading, black EPDM weatherproof roof covering, with an exceptional 50-year life expectancy. This rubber roof covering will not split or crack, does not support moss or algae growth, is UV-stabilised and is completely maintenance free. Anthracite grey facias complete the modern finish. Easy Electrical Installation Forest do not offer an electrical service. However, the 28mm wall battens and 45mm roof battens are designed to leave enough space to add electrical wiring and recess lights respectively. Electrical work should always be undertaken by a qualified electrician. Secure UPVC Double Glazed Doors and Windows Entry to this SIP garden office is gained via UPVC double-glazed, double doors, which are secured by a 7-point multi-lock to keep expensive equipment safe. Two additional full-length, double-glazed windows ensure the interior benefits from an abundance of natural light. The top half of both windows opens for ventilation. The doors and windows all have grain-effect grey outer and smooth white inner frames, making for an exceptionally attractive appearance. Options Available and Assembly This top-of-the-range insulated SIP garden room is available in 3 sizes and with 3 different door/window configurations. Fixtures, fittings, exterior facias and a step-by-step installation guide are all included for a . simple assembly. Forest do offer a professional installation service carried out be expert fitters. Energy Efficiency and Care Instructions This SIP garden office has an energy efficiency rating of 78 (category C) and has the potential to reach 82 (category B), with the addition of a photovoltaic solar panel. The outdoor office is delivered untreated. As such, the exterior should be treated upon assembly and again each year. Forest Garden recommend that it is cared for with one of the following: Sikkens Cetol HLS Plus, Restol Wood Oil, Timmersol ETS Double Protectant, Osmo Country Colour or Osmo Natural Oil Wood Stain. The internal cladding comes with primer applied, so can be painted in any colour using standard interior emulsion paint. Delivery Delivery is free to most UK addresses. Some remote postcodes may incur surcharges. Please see the delivery information for further details. Explore our full range of garden offices to find the perfect fit for your garden. Reasons to buy the Xtend 4.0+ Fully Insulated SIP Garden Office from Shedstore: 15-year structural guarantee UK-made from revolutionary Structural Insulated Panels (SIPs), this SIP garden room provides thicker, better, year-round insulation. Ideal for use as a SIP garden office 15mm tongue and groove external cladding and MDF interior walls 108mm SIP floor and 122mm SIP roof for top-to-bottom insulation EPDM weatherproof roof covering, with a 50-year life expectancy Double-glazed, UPVC d

Full specifications

Marque Forest Xtend
EAN 5013053183632

Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm): complete technical analysis for 2026

The Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) is a well-regarded reference in the Bureautique & Papeterie category. In 2026, it remains one of the most relevant choices for those seeking to balance quality and budget. The brand Forest Xtend has a strong reputation among consumers, reflected in its consistent availability across many partner retailers. Thanks to our comparison tool, you can see all available offers at a glance and go directly to the retailer of your choice to complete your purchase with confidence.

Who is this Bureautique & Papeterie for?

The Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) benefits from the expertise of Forest Xtend in this category. Its design meets current market standards and satisfies even the most demanding users in their everyday activities. The brand's reliability translates into positive feedback from regular buyers, who particularly appreciate the consistency between the promises of the product sheet and the real-world experience. For the Bureautique & Papeterie category, this is an option we recommend without hesitation.

For intensive or occasional use

The Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) adapts to different levels of use in the Bureautique & Papeterie category. Whether you use it intensively every day or more occasionally, this Forest Xtend product offers appreciated versatility. Regular users value its reliability over time, while occasional users appreciate how easy it is to pick up without any special training. For even more demanding use, also check the Forest Xtend 3.0 Insulated Garden Office 2.98m x 2.9m (97mm).

Against the competition

In the Bureautique & Papeterie market, the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) is well positioned thanks to its price from £12,619.99 and the strength of Forest Xtend. Our comparison tool lets you verify in real time whether this positioning still holds against other available offers.

Market price ranges in 2026

RangeIndicative price
Entry-levelUnder 3790 £
Mid-range3790 £ to 8840 £
High-endOver 8840 £

The best times to buy the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) at a lower price are Black Friday in November, the January sales and the summer sales in July. Our price history lets you judge whether the current price is a genuine bargain or whether it is worth waiting a few weeks. Outside these periods, flash promotions remain frequent among Compiral's partner retailers.

Frequently asked questions about Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm)

How does the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) compare to competitors in the Bureautique & Papeterie category?

In the Bureautique & Papeterie category, the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) occupies a specific market segment. Compared to other available models, it stands out mainly through the balance between its features and its price. To compare objectively, consult the detailed spec sheet on this page and compare specifications with other similar products listed on our comparison tool.

Is the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) suitable for beginners?

Yes, the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) is generally appreciated by both beginners and regular users of the Bureautique & Papeterie category. It is quick to set up and Forest Xtend usually provides clear documentation. If you are new to this product category, consult the spec sheet on this page to identify the key criteria to check before making your choice.

Is there a refurbished version of the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm)?

Refurbished versions of the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) may be available from certain Compiral partner retailers. These refurbished products allow you to save between 20% and 40% compared to the new price while still benefiting from a warranty. Check availability in our offers table and review the warranty conditions offered by the retailer.

When do prices for the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) drop during the year?

Prices for the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) typically drop during Black Friday (November), the January sales and the summer sales (July). Promotional deals are also common around Cyber Monday and the holiday season. Our price history lets you spot trends and assess whether a price drop is likely soon in the Bureautique & Papeterie category.

Is delivery free for the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) at all retailers?

Free delivery is not guaranteed for the Forest Xtend 4.0+ Fully Insulated SIP Garden Room Office with UPVC Double Doors 4.05m x 3.42m (97mm) at every retailer. Some include it in their price, others charge separately. On Compiral, use the free delivery filter to display only offers with free postage. The total price shown in our table always includes delivery costs for a true cost comparison.

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