13 x 11 (4.05m x 3.42m) Forest Xtend 4.0+ Insulated Garden Office with Double Door

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13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - insitu
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - insitu
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - close up of 1/2 opening side wind
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door -  internal working and social spac
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - internal working and social space
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - use as a fitness room
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - use as a health room
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - close up of front roof overhang
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - close up of internal door
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - dimensions
  • 13x11 Forest Xtend 4.0+ Insulated Garden Office with Double Door - floor plan

13 x 11 (4.05m x 3.42m) Forest Xtend 4.0+ Insulated Garden Office with Double Door

NEW - Sale
NEW - Guarantee - 15 year - gold
NEW - Installation - Express Installation

Product Code - 90040037

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Usually delivered: 30-40 Working Days. (+15 Extra Working Days with Installation Option).

excludes installation option
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  • 13 x 11 (4.05m x 3.42m) Forest Xtend 4.0+ Insulated Garden Office with Double Door£13,393.04


            Forest Xtend 4.0+ Insulated Garden Office

            As more and more of us are working from home, the need for a quiet, dedicated home office is becoming urgent for people all over the UK. You can achieve the perfect work/life balance by opting for a garden home office. The Xtend 4.0+ from Forest offers just about everything you could need in a home office. It boasts a clean, contemporary look, it stays cool in the summer and warm in the winter, it is surprisingly easy to build and, most importantly, it costs a fraction of the price of a traditional home extension. With an opening side window as part of the package too (you'd be surprised how many similar products don't include one!) regulating the internal temperature and airflow is a breeze. Available in a range of sizes, there is certain to be an Xtend to suit your needs.

            As if that wasn't enough, Forest can deliver the Xtend within 3-4 weeks of you placing an order, so you can be up and running in your new home office in next to no time! If you have a little more time to work with, the delivery time increases only to 5-6 weeks if you want to take advantage of Forest's professional assembly service. By choosing assembly, you can sit back, relax, and have your new workspace built for you. If you can find someone to build a conventional extension on your home within 6 weeks at the same price or better than the Xtend, we suggest you take them up on the offer! Please be aware, however, that these timescales may be extended during peak times of the year or due to unforeseen circumstances.

            Why Buy an Xtend?

            If you have found yourself trying to work in a cramped spare bedroom while the sound of the washing machine provides a constant distraction, or perhaps you have had one instance too many of the family pet or one of your children making a surprise appearance in a video meeting, the Xtend could be precisely what you need to ensure distractions are a thing of the past. Not to mention, having a garden home office would mean no more commuting, more time spent at home with loved ones, and more space freed up in your house for other uses. Plus, with a 15-year structural guarantee, you can rely on your new home office to provide valuable working space for many years to come. Join the revolution today and see exactly why more and more people are choosing to have an office in their garden!

            Don’t have a desk job or can’t work from home? No problem! The Insulated Garden Office could provide you with the perfect space to set up for a variety of different business types, or could just as easily be used as somewhere to spend your leisure time. We regularly see garden buildings such as the Xtend used by beauticians, nail technicians, dog groomers, massage therapists, personal trainers, and more! And of course, the Xtend is not just a building perfectly suited to work use. It could be just the space you need to set up an art studio, a music room, a fitness suite or even simply a quiet spot for rest and relaxation in the tranquil setting of your garden. The possibilities are almost limitless, but you may take extra inspiration from checking out our product images, showing some of the great ways you can take advantage of the Xtend.

            See our key features tab for more information about the Xtend’s quality components.

            About Forest

            Forest Garden Ltd is the UK's leading manufacturer and distributor of timber garden products. They are proud to be a British company using sustainable, British timber. The majority of the timber they use is grown and felled from managed UK forests across Scotland. After felling, the timber is cut and processed in a nearby sawmill and taken to their manufacturing operation in rural Worcestershire. At their manufacturing site, they are always investing in technology to ensure product consistency and quality. It is there that they produce the widest range of garden buildings, fencing and structures available in the UK. Many of Forest’s products come with high specification features at no extra cost, and they also offer free delivery and pick your own delivery dates to the vast majority of mainland UK addresses. This cements their reputation as the “go-to” choice for thousands of customers looking to enhance their gardens every year.


            DELIVERY IS MADE TO THE KERBSIDE OR DRIVEWAY AND IS DELIVERED ON AN HI-AB. All Forest products are delivered in a flat-packed format, accompanied by a comprehensive set of instructions to facilitate self-assembly

            If you have ordered more than one item, they may arrive at different times.


            Most UK postcodes qualify for FREE delivery; however, certain regions may be subject to a delivery surcharge, while others may not be covered at all. During the checkout process, you will receive a notification if your area incurs an additional fee or if delivery is unavailable in your region.

            Forest or their selected courier will contact you closer to the estimated delivery date to provide the specific delivery schedule. If the proposed date is inconvenient, you can respond to the message to arrange a more suitable delivery date. The delivery timescales mentioned on the product page apply to your order.

            In these areas, the delivery timescales may be extended by an additional 5-10 working days.
            AB1, AB10,-AB16, AB21-AB25,AB30-AB39, AB41-AB45, AB51-AB56, CA1-CA28, CO1-CO16, DD1-DD10, DG1-DG14, DG16. DH1-DH9, DL1-DL17, DT3-DT7, EH1-EH2,EH10-EH1-EH49,EH51-EH55, EX1-EX24,EX31-EX38, FK1-FK21, G1-G5,G11-G15,G20-G23,G31-G34,G40-G46, G51-G53,G60-G69,G71-G78,G81-G84, IP1-IP33, IV1-IV28,IV30-IV32,IV36,IV40,IV54,IV63, KA1-KA30, KW1-KW14, KY1-KY16, ML1-ML12, NE1-NE1-NE49,NE61-NE70, NR1-NR35, PA1-PA38, PE30-PE37, PH1-PH26, PH30-PH41,PH49-PH-PH50, PL1-PL35, SR1-SR8, TA20, TA22, TD1-TD15, TQ1-TQ14, TR1-TR20,TR26-TR27, AND TS1-TS29.

            We apologize, but Forest does not provide delivery or assembly services for the following postal codes:
            BT1-BT99, GY1-GY9, HS1-HS9, IM1-IM9, IV41-IV56, JE1-JE5, KA27-KA28, KW15-KW17, PO30-PO41, PO49, TR21-TR25.

            Before the Delivery

            Once you have a confirmed delivery date, please ensure that you provide us with your mobile number as the primary contact number, rather than an alternative number. This will allow us to inform you the 2 working days before delivery whether it will be scheduled for the morning or afternoon.

            Upon Delivery

            Your order will be delivered to the kerbside or your driveway. For reasons related to health, safety, and insurance, the driver is unable to transport the goods to the rear of your property.  Please note that we are unable to enter your property during the delivery process.

            We strongly advise against arranging for a third party to install the product before it is delivered. Additionally, it is important to check that all parts are present upon delivery. We cannot be held responsible for any costs incurred due to delays caused by third parties.

            Orders with optional Assembly

            It is not possible to pre-book a delivery or installation date at the time of placing your order. The arrangement for delivery and installation will be made directly with the manufacturer. Please note that delivery and installation will take place on separate days.

            In addition to the delivery lead time mentioned on this page, there is an additional lead time of approximately 15 working days (which may be extended during peak times). The product will be delivered 1-3 working days prior to your scheduled installation date.

            Within 5 working days from the time you place your order, the manufacturer will reach out to you by telephone with instructions on how to prepare the base for installation and to ensure there are no parking or site access restrictions. The base should be either a solid concrete surface or concrete slabs. It is important to have a clearance of 18 inches (450mm) around the base, providing sufficient working space for the installers to access all areas of the structure.

            After receiving the email from the manufacturer, you can expect a phone call shortly thereafter to schedule a convenient date for delivery and installation.


            Please note: all imperial measurements are approximate, and the Forest Gardens Insulated Garden Offices are made from metric measurements. We would recommend that the base is at least 50mm bigger in each direction.

            Product Name:
            13 x 11 (4.05m x 3.42m) Forest Xtend 4.0+ Insulated Garden Office with Double Door
            Optional Installation:
            4.05m (13'3")
            3.42m (11'3")
            Footprint Width:
            4.03m (13'2")
            Footprint Depth:
            3.04m (9'11")
            Footprint Width (Internal):
            3.67m (12'0")
            Footprint Depth (Internal):
            2.68m (8'9")
            Height to Ridge:
            2.50m (8'2")
            Height to Eaves:
            2.40m (7'10")
            177mm - including SIP Panels, internal and external Cladding and cavities
            Internal: 97mm insulated walls - 75mm Polystyrene Insulation between two sheets of OSB

            External: 15mm thick premium interlocking Tongue and Groove boards mounted to framing batons
            Floor Material
            SIP Panels - Boarded, Oriented Strand Board (OSB) and tongue and groove
            Floor Thickness:
            Floor Joists:
            70mm x 45mm 23 /4" x 12 /3")- Wrapped in a damp proof membrane
            Floor Joist Direction:
            Front to back
            Roof Type:
            Roofing Felt:
            EPDM - 50 Year roof life expectancy
            Roof Material:
            Double OSB skinned with Insulation between
            Roof Thickness:
            11mm OSB x 100mm Insulation x 11mm OSB
            Roof Joists:
            Double uPVC reinforced 5 Chamber
            Door Height:
            1.95m (6'5")
            Door Width:
            0.75m (2'5")
            Door Lock System:
            7 point multi-Lock with ultion three star security barrel
            Number of Windows:
            2x Full Length Window with 12 Opening
            Window(s) and Door location:
            Front Width: Central Doors
            Front Width: 1 x full-length window uPVC 5 chamber with 12opening

            Depth: 1x uPVC 5 chamber full-length side window with 12 Opening
            Window Material:
            28mm double glazing safety glass with energy rating A
            Window Height:
            Window Width:
            Optional Roofing Felt Tiles:
            Optional Base (to be used instead of a concrete base)
            None - kiln dried
            Recommended Treatment:
            External: Cetol HLS Plus, Restol Wood Oil, Timmersol ETS Double Protectant, Osmo Country Colour, Osmo Natural Oil Woodstain
            Internal: Protek Range (please click here)
            Energy Rating for Building:
            Energy efficiency model rating of 78 (category C)* with potential to increase to 82 (category B) with the addition of a photovoltaic solar panel
            Manufacturer's Guarantee:
            Underwritten with a 15 year structural guarantee
            FSC Certified:
            Free Delivery*:
            Product Code:
            Manufacturer Code:
            EAN Number:
            5013053183632 and 5013053183656
            Forest Garden Ltd
            Country of Origin:
            United Kingdom
            Click to View Alternative Sizes:
            Width x Depth:
            2.54m x 2.90m

            2.54m+ x 2.90m

            2.98m x 2.90m

            2.98m+ x 2.90m

            4.05m x 3.42m

            4.05m+ x 3.42m


            The Forest Xtend 4.0+ Insulated Garden Office with double doors and 2 fixed long windows which includes a 1/2 opening side window on the front and side elevation, provides the perfect workspace solution for anyone who works from home. Away from the distractions of your home, it provides a quiet environment that is perfect for concentrating on your work. Say goodbye to being cramped into a small spare bedroom or getting back ache from trying to work in your bed! Just some of the key features of this superb building include:

            • Highly energy efficient, and remains warm in the winter while cool in the summer; read more below for extra detail about how this is achieved
            • Comes with a 15-year structural guarantee, so it can be relied upon to provide many years of service
            • A much cheaper alternative to a traditional extension and is delivered free to most UK mainland addresses
            • State-of-the-art manufacturing techniques ensure a building that is surprisingly straightforward to assemble

            Key Features

            Structural Insulated Panels (SIPs)
            • The core structure of an Xtend building is made from SIPs panels - a high performance material for building construction. The 21st century way to build
            • 7mm thick insulated walls consist of 75mm of polystyrene insulation sandwiched between two sheets of oriented strand board (OSB)
            • Gives structure and insulation in one pre-assembled and cut-to-size panel
            • Total wall thickness, including SIPS panels, internal and external cladding and cavities, is 177mm
            • Roof is 11mm OSB + 100mm insulation + 11mm OSB = 122mm total
            • This all comes together to make for a snug interior during the colder months, but also one that remains cool during the summer
            External Cladding 
            • Pre-cut external timber cladding panels for quick and easy assembly; many modern homes are now built in this way, so why not your home office?
            • No measuring and cutting every single batten and board to size before mounting
            • Cladding panels are simply positioned on the building and screwed into place
            • Panels are made with 15mm thick premium interlocking tongue and groove boards mounted to framing battens
            • Comes untreated, so you must apply a suitable timber treatment of your choice. The manufacturer recommends: Sikkens Cetol HLS Plus; Restol Wood Oil; Timmersol ETS Double Protectant; Osmo Country Colour; Osmo Natural Oil Woodstain
            Internal Cladding
            • Pre-cut interior MDF panels for quick and easy assembly of walls and ceiling
            • No measuring and cutting every panel
            • Wall panels are mounted to 28mm thick battens creating a cavity perfect for routing electrical wiring (we recommend you consult a trained electrician when installing electrics)
            • Roof battens are 45mm thick to allow for recess roof lights
            • Comes with primer applied – can be painted in a colour of your choice using standard interior emulsion paint
            • The panel design has a vertical beaded profile
            • The floor is left unfinished for you to add your own choice of covering
            • Includes damp proof membranes
            Roof Covering 
            • External roof covering is made from 1.2mm thick EPDM black rubber
            • It creates a maintenance free waterproof membrane
            • Does not crack, split or rot
            • Does not support moss or algae growth
            • UV stable & environmentally friendly
            • Safe and easy to install – the system is laid with cold applied adhesives (supplied)
            • One piece sheet means no joints and no leaks
            • 50 years roof life expectancy
            • Anthracite grey fascias included
            • Cladding on under-hangs
            Windows & Doors
            • Window material: uPVC 5 chamber
            • Window colour: Anthracite grey externally with grained finish smooth white internally
            • Window locking: Two double clasp, mushroom headed espagnolettes
            • Door material: uPVC reinforced 5 chamber
            • Door colour: Anthracite grey externally with grained finish, smooth white internally
            • Door locking: 7-point multi-lock with ultion three-star security barrel, providing peace of mind when leaving valuables inside
            • Glazing 28mm, A-rated, double glazed, safety glass
            • Opening side window allows you to regulate the internal temperature and airflow with ease
            Energy Efficiency
            • Highly efficient due to insulated walls, roof, and floor
            • Double glazed windows
            • Warm in Winter, cool in Summer
            • Energy efficiency model rating of 78 (category C)*
            • Potential to increase to 82 (category B) with the addition of a photovoltaic solar panel
            • *Based on lighting from 3 x 4 watt LED bulbs and heat from a high efficiency wall mounted heat pump
            Why Choose the Forest Xtend?
            • Can be delivered within 3-4 weeks, one of the fastest (if not the fastest) timescales for any similar products on the market; please be aware that this may be extended during peak times
            • Not all our competitors offer installation; so, if you want to avoid the hassle of ringing around for quotes, or indeed having to spend your valuable time building it yourself, Forest offer optional assembly for a great price
            • Xtend has a market-leading and verified energy efficiency rating
            • Walls are as much as 47% thicker than similar products on the market
            • Roof up to 30% thicker than competitors
            • Under-hangs feature cladding for a superior look and less maintenance; many competitor products do not, leaving buildings looking unfinished
            • The Xtend features damp proof membranes
            • A floor that is as much as 400% thicker and better insulated than some other leading products
            • Easier to build thanks to its state-of-the-art design
            • Free delivery to Mainland UK with almost no exceptions; some competitors charge as much as £600 for delivery to certain areas
            • Some similar products don’t include a side window, and if they do, it isn't always an opening window
            • A comprehensive 15-year warranty, whereas most competitors only offer a 10-year guarantee
            • Primer pre-applied to interior walls, meaning you can paint straight onto them with interior paint
            • Xtend has hidden nail panels for a sleek, professional finish
            • Hard-to-beat pricing when compared to competitors, especially for such a high-quality product

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