Forest Xtend 3.0 Insulated Garden Office 2.98m x 2.9m

The Forest Xtend 3.0 Insulated Garden Office (XTEND3.0HDBUN) is a pent-roof garden room measuring 2.98m x 2.9m (approximately 10ft x 10ft) externally. That gives you an internal floor area of 2.65m x 2.15m enough for a proper home office setup without wasted space.

Built from Structural Insulated Panels (SIPs) throughout walls, floor and roof, this is not a standard timber shed dressed up as an office. The 97mm SIP walls combine 75mm polystyrene insulation between two OSB sheets, then add 15mm tongue and groove external cladding plus internal MDF cladding for a total wall thickness of 177mm. The floor SIP is 108mm thick and the roof SIP is 122mm. The EPDM rubber roof membrane has a 50-year life expectancy and needs no maintenance.

Entry is via a double-glazed uPVC door secured by a 7-point multi-lock with Ultion Three Star Security Barrel. Three full-length double-glazed uPVC windows flood the interior with natural light and one opens for ventilation. All glazing is 28mm A-rated safety glass. 28mm wall battens and 45mm roof battens leave cavities for routing electrical wiring and recessed lights a qualified electrician fits these separately.

With an EPC rating of 78 (Category C) this building is genuinely usable year-round. It carries a 15-year structural guarantee and arrives with all fixtures, fittings and a step-by-step assembly guide included.

The Xtend 3.0 uses Structural Insulated Panels for walls, floor and roof not just walls. Each wall SIP is 97mm thick: 75mm polystyrene insulation bonded between two OSB sheets. Add 15mm tongue and groove external cladding and 28mm internal battens plus MDF lining and the total wall build-up reaches 177mm. The floor SIP is 108mm and the roof SIP is 122mm. The roof is finished with 1.2mm EPDM rubber UV-stabilised, crack-resistant and rated for 50 years. All glazing is 28mm A-rated double glazed safety glass in 5-chamber uPVC frames. The result is an EPC rating of 78 (Category C).

Structure: Structural Insulated Panels (SIPs) 75mm polystyrene core bonded between two OSB sheets. External cladding: 15mm kiln-dried tongue and groove timber. Internal lining: MDF with vertical beaded profile, primed. Floor: 108mm SIP, unfinished. Roof: 122mm SIP with 1.2mm EPDM rubber membrane. Doors and windows: 5-chamber reinforced uPVC with 28mm A-rated double glazed safety glass.

A solid, level base is required before delivery or installation this is the buyer's responsibility. Forest specify the base must be complete before any installation date is booked. No base is supplied with the building. The floor SIP is included but arrives unfinished you add your own floor covering such as carpet or laminate.

The Xtend 3.0 arrives as pre-cut modular SIP panels ready to assemble. All fixtures, fittings, anthracite grey exterior fascias and a step-by-step installation guide are included. Assembly is described as straightforward. No explicit build time is stated by the manufacturer. Two or more people are recommended for handling the SIP panels safely. An optional professional installation service is available at extra cost.

Forest offer a professional installation service carried out by their own expert fitters, available as a paid add-on at checkout. The base must be solid and level before the installation date. Installation covers the building structure only it does not include electrics, base preparation or any accessories.

No electrical wiring is supplied or installed. The building is designed with 28mm wall battens and 45mm roof battens that leave cavities for routing cables and recessed ceiling lights. All electrical work must be carried out by a qualified electrician after the building is assembled.

Treat the exterior timber cladding immediately on assembly then retreat every year Forest recommend Sikkens Cetol HLS Plus, Restol Wood Oil or Osmo products. The EPDM roof covering is fully maintenance free and does not support moss or algae growth. Annual treatment of the timber is required to maintain the 15-year structural guarantee.

The internal floor space is 2.65m x 2.15m roughly 5.7 square metres. That comfortably fits a desk, monitor setup and office chair with room for shelving or a filing cabinet. It is tight for two full desks but works well as a solo home office. The full-length windows and 2.4m eaves height keep it feeling open. The SIP insulation means it works as a year-round gym for cardio equipment or a yoga space. It also suits a hobby room, music practice space or a compact creative studio.

Most garden offices in England fall under permitted development and do not need planning permission. This model has a ridge height of 2500mm and eaves height of 2400mm. Rules differ in Scotland, Wales and Northern Ireland and on designated land. Always check with your local planning authority before you build this is not legal advice.