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Where to Buy Garden Room Supplies
Whether you are ordering a pre-built garden room or fitting one out yourself, these suppliers cover the essentials.
| Retailer | What to Buy | Why We Recommend |
|---|---|---|
| Amazon UK | Electric panel heaters, LED panels, cable, insulation, furniture | Best range of heating and lighting at competitive prices, Prime delivery |
| B&Q | Timber, insulation boards, plasterboard, screws, flooring | Everything for DIY builds, click & collect nationwide |
| Wickes | Structural timber, OSB, insulation, electrics, plumbing | Trade quality, good bulk pricing on building materials |
Prices vary by supplier and region. Links help support this free tool.
How Much Does a Garden Room Cost in the UK?
A garden room in the UK typically costs between £15,000 and £40,000 for a standard insulated build with electrics. The price depends primarily on three things: the floor area, the specification level and whether you need foundations built from scratch.
At the budget end, a basic insulated shell of around 9m² (3m x 3m) starts at approximately £12,000-£15,000 from national suppliers. This gives you a watertight, insulated room but typically without electrics, internal lining or heating. You would need to spend another £2,000-£4,000 finishing the interior and running a power supply to make it usable as a year-round office.
The mid-range sweet spot is a 12m² (4m x 3m) standard-specification garden office at £20,000-£28,000. At this level, you get full insulation, double or triple-glazed windows and bifold or sliding doors, internal plasterboard or ply lining, a consumer unit with sockets and lighting, and usually a basic heating solution. This is what most people buying a garden office for remote work end up spending.
Premium and bespoke builds start at around £2,200/m² and can exceed £3,500/m² for architect-designed rooms with cedar cladding, green roofs, floor-to-ceiling glazing, underfloor heating and integrated AV systems. A 20m² (5m x 4m) premium garden room with a WC and kitchenette can easily reach £50,000-£70,000.
Garden Room Costs by Size (2026)
| Size | Floor Area | Basic | Standard | Premium |
|---|---|---|---|---|
| Small (2.5m x 2.5m) | 6.25 m² | £7,500-£10,000 | £10,500-£14,000 | £14,000-£18,000 |
| Compact (3m x 3m) | 9 m² | £10,800-£13,500 | £15,300-£19,000 | £19,800-£25,000 |
| Standard (4m x 3m) | 12 m² | £14,400-£18,000 | £20,400-£25,000 | £26,400-£33,000 |
| Large (5m x 3m) | 15 m² | £18,000-£22,500 | £25,500-£31,000 | £33,000-£41,000 |
| Extra Large (5m x 4m) | 20 m² | £24,000-£30,000 | £34,000-£42,000 | £44,000-£55,000 |
| Studio (6m x 4m) | 24 m² | £28,800-£36,000 | £40,800-£50,000 | £52,800-£67,000 |
Note: Prices include VAT at 20% but exclude foundations and electrics, which add £3,000-£6,000 to the total. London and South East prices are typically 10-20% higher than national averages.
Garden Room vs House Extension — Which Is Better Value?
This is the question that almost every homeowner considering a garden room eventually asks. Both add usable living space, but the costs, timescales and planning requirements are dramatically different.
A single-storey rear house extension costs £1,800-£3,000 per square metre in 2026 — roughly the same per-square-metre as a mid-to-premium garden room. But extensions involve far more disruption: weeks of builders inside your house, structural alterations, building regulations inspections, and almost always planning permission or a lawful development certificate. A typical 15m² rear extension takes 8-12 weeks on site and costs £30,000-£50,000 all in.
A garden room of the same size can be installed in 1-3 weeks with zero disruption to the house. No internal walls are knocked through, no dust throughout the home, no temporary kitchens. Most garden rooms fall under permitted development, so no planning application is needed — saving 8-12 weeks of waiting before work can even start.
Where extensions win is in added property value. An extension that creates a larger kitchen-diner or an extra bedroom adds more to your asking price than a garden room of the same size. Estate agents estimate an extension adds 10-20% to property value versus 5-15% for a garden room. But if your primary goal is a home office, studio, gym or therapy room, a garden room delivers that space faster, cheaper and with far less upheaval.
| Factor | Garden Room | House Extension |
|---|---|---|
| Cost per m² | £1,200-£2,800 | £1,800-£3,500 |
| Build time on site | 1-3 weeks | 8-12 weeks |
| Planning permission | Usually not needed | Usually needed |
| Building regulations | Not usually required | Always required |
| Disruption to home | None | Significant |
| Added property value | 5-15% | 10-20% |
| Best for | Office, studio, gym | Kitchen, bedroom, living space |
Garden Room Foundations — Which Type Do You Need?
Every garden room needs a level, stable foundation. The right choice depends on your ground conditions, budget and how permanent you want the structure to be. Many homeowners underestimate the foundation cost and are surprised when it adds £1,500-£5,000 to the project. Here are the four main options available in the UK.
Concrete Plinths or Piers
The simplest and cheapest option. Individual concrete pads or blocks are placed at load-bearing points under the garden room frame. They work well for smaller buildings (under 12m²) on firm, level ground. Cost: £800-£1,500 depending on the number of plinths. The advantage is speed — a competent DIYer can prepare these in a day. The downside is that they require the ground to be relatively flat and firm. On sloping or soft ground, they are not suitable.
Ground Screws
Ground screws are steel helical piles that are screwed into the ground using a machine, with a steel frame or timber bearers bolted on top. They have become the most popular foundation type for garden rooms in the past five years. Cost: £1,200-£2,500 for a typical 12-15m² garden room. The advantages are significant: minimal ground disruption (no excavation), installation takes half a day, they work on most soil types including clay, and they can be removed if you ever want to relocate the building. Some mortgage lenders and insurers prefer ground screws because they are considered less permanent than concrete.
Concrete Slab
A poured concrete slab provides the most uniform support and is the traditional choice for larger garden rooms and those with heavy internal loads (such as a gym with equipment). Cost: £1,500-£3,000 for a 12-15m² slab including excavation, hardcore, membrane, mesh and concrete. A concrete slab takes 2-3 days to prepare and needs 3-7 days to cure before the garden room can be built on top. It is the most permanent option and the hardest to remove.
Concrete Pad Foundations
Individual concrete pads at each structural post location, connected by a steel or timber frame. This is the professional standard for larger and heavier garden rooms (15m²+). Cost: £2,000-£4,000 depending on the number of pads and ground conditions. Pad foundations cope well with sloping ground because each pad can be at a different depth. They require a builder or groundworker with experience in setting out levels accurately.
| Foundation Type | Cost (typical 12m²) | Install Time | Best For | Removable? |
|---|---|---|---|---|
| Concrete plinths | £800-£1,500 | 1 day | Small builds, flat firm ground | Yes |
| Ground screws | £1,200-£2,500 | Half day | Most garden rooms, clay soil | Yes |
| Concrete slab | £1,500-£3,000 | 2-3 days + curing | Heavy loads, gyms, level ground | Difficult |
| Concrete pads | £2,000-£4,000 | 2-3 days + curing | Larger builds, sloping sites | Difficult |
Planning Permission for Garden Rooms — UK Rules (2026)
The majority of garden rooms in England do not require planning permission because they qualify as permitted development under the Town and Country Planning (General Permitted Development) Order. However, the rules are specific and getting them wrong can result in an enforcement notice requiring you to demolish the building. Here is exactly what you need to know.
Permitted Development Conditions
Your garden room qualifies as permitted development if ALL of the following conditions are met:
Height: Maximum eaves height of 2.5 metres. For a dual-pitched roof, maximum overall height of 4 metres (or 3 metres if within 2 metres of a boundary). For a flat or mono-pitch roof, maximum overall height of 3 metres.
Coverage: The total area of all outbuildings (sheds, garages, garden rooms combined) must not cover more than 50% of the total garden area. The garden area is defined as the land around the house, excluding the footprint of the original house.
Location: The garden room must not be in front of the principal elevation (the front of the house that faces the road). It must not be on designated land (conservation areas, national parks, AONBs, World Heritage Sites) without additional conditions being met.
Use: The building must be incidental to the enjoyment of the dwelling house. This means it can be used as an office, studio, gym, playroom or hobby room — but NOT as self-contained living accommodation with sleeping, cooking and bathing facilities. Adding a bedroom or a full kitchen could push you into needing planning permission.
When You DO Need Planning Permission
You will need to submit a planning application if:
The garden room exceeds permitted development size limits. Your property is a listed building (listed building consent is also required). The garden room is in front of the house. You want to use it as separate accommodation (an annexe or holiday let). Your property is in a conservation area, national park or AONB and the building is more than 10m². You have already used your permitted development rights for other outbuildings.
A planning application typically costs £234 in England (2026) and takes 8-12 weeks for a decision. If in doubt, contact your local planning authority for pre-application advice, which costs £50-£300 depending on the council.
Building Regulations
Garden rooms under 15m² floor area with no sleeping accommodation are generally exempt from building regulations. Between 15m² and 30m², the building is exempt provided it is at least 1 metre from any boundary or is constructed of substantially non-combustible materials. Over 30m², building regulations approval is required. Regardless of size, any electrical work must comply with Part P and should be carried out or certified by a qualified electrician registered with a competent person scheme.
Garden Room Electrics — What You Need and What It Costs
Unless you plan to use your garden room only in summer daylight hours, you will need an electrical supply. Running electrics to a garden room is not a DIY job — it must be done by a qualified electrician registered with a Part P competent person scheme (such as NICEIC, NAPIT or ELECSA).
What Is Involved?
A typical garden room electrical installation includes: an armoured SWA cable run from the main house consumer unit to the garden room (buried in a trench at minimum 450mm depth), a small consumer unit (mini CU) in the garden room with an RCD, double sockets (typically 4-8 depending on the room size), LED downlights or panel lights, an outdoor light above the door, and an electric heater circuit if needed. For a garden office, you also want at least one dedicated circuit for a computer and monitor, and ideally a USB charging socket.
Electrical Installation Costs (2026)
| Item | Cost | Notes |
|---|---|---|
| Armoured cable supply (up to 25m) | £800-£1,500 | Includes trenching, cable, connection to main CU |
| Mini consumer unit | £150-£300 | Installed in garden room with RCD protection |
| Double sockets (4-6) | £200-£400 | Standard and USB sockets |
| LED lighting (4-6 downlights) | £200-£400 | Including switch and dimmer |
| External light | £80-£150 | PIR sensor or dusk-to-dawn |
| Electric panel heater circuit | £100-£200 | Dedicated circuit for heater |
| Electrical certificate (Part P) | Included | Must be issued on completion |
| Typical total | £1,500-£3,000 | Depends on cable run length and socket count |
Important: Longer cable runs cost more. If your garden room is 30m+ from the house, the cable cost alone can be £1,000-£2,000. Some garden room suppliers include electrics in their price — always ask what is and is not included before comparing quotes.
How to Heat a Garden Room — Options and Running Costs
A well-insulated garden room holds heat surprisingly well. With 100mm insulation in the walls, floor and roof, a 12m² garden office needs only 1-1.5kW of heating to maintain a comfortable 20°C on a cold winter day. The question is which type of heating to use.
Electric Panel Heaters
The most common choice for garden offices. A 1kW electric panel heater costs £100-£300 to buy and roughly 30p per hour to run at 2026 electricity rates (approximately 30p/kWh). For a standard garden office used 8 hours a day through winter (November to March), that is around £300-£400 per winter in heating costs. Panel heaters are cheap to install, reliable and give instant heat. The downside is they are the most expensive option to run long-term.
Infrared Heating Panels
Infrared panels heat objects and people directly rather than the air, which makes them more efficient in well-insulated spaces. A 700W infrared panel costs £200-£500 and heats a 10-12m² room. Running costs are lower than conventional heaters — roughly 20p per hour. They mount on the ceiling or wall and produce no noise. The main drawback is they take 15-20 minutes to feel effective because they warm surfaces, not air.
Underfloor Heating
Electric underfloor heating mats cost £1,000-£2,500 installed and provide an even, comfortable warmth. Running costs are moderate at around 25-35p per hour for a 12m² room. The main advantage is freeing up wall space and providing a luxury feel underfoot. The main disadvantage is that underfloor heating is slow to warm up — it takes 30-60 minutes to reach temperature, so it works best left on a timer or thermostat rather than switched on and off throughout the day.
Mini-Split Air Source Heat Pump
A wall-mounted mini-split heat pump provides both heating in winter and cooling in summer. Installation costs £1,500-£3,000, but running costs are the lowest of any option — roughly 8-12p per hour — because heat pumps deliver 3-4 units of heat for every 1 unit of electricity consumed. For a garden room used year-round, a mini-split is the most cost-effective heating solution over its 15-20 year lifespan. The downside is the higher upfront cost and the external unit, which some people find visually intrusive.
| Heating Type | Install Cost | Running Cost/Hour | Annual Heating Cost | Best For |
|---|---|---|---|---|
| Electric panel heater | £100-£300 | ~30p | £300-£400 | Occasional use, low budget |
| Infrared panel | £200-£500 | ~20p | £200-£300 | Well-insulated rooms, silent heating |
| Underfloor heating | £1,000-£2,500 | ~25-35p | £250-£350 | Year-round use, comfort-focused |
| Mini-split heat pump | £1,500-£3,000 | ~8-12p | £100-£180 | Year-round use, most efficient |
Annual heating costs assume a 12m² garden office used 8 hours per day, November-March, at 2026 UK electricity rates of approximately 30p/kWh.
Garden Room Insulation — Getting It Right
Insulation is what separates a garden room you can use all year from a glorified shed you abandon in October. A properly insulated garden room maintains a comfortable temperature in both summer and winter, reduces heating costs dramatically and prevents condensation damage to the structure and your equipment.
Insulation Standards
Although garden rooms are generally exempt from building regulations, you should aim for the same insulation standards as a house extension. A minimum of 100mm insulation in the walls, floor and roof gives you a U-value of around 0.2 W/m²K, which is comparable to a modern house wall. Most reputable garden room manufacturers build to this standard or better.
Insulation Types
PIR boards (Celotex/Kingspan): The most common insulation for garden rooms. 100mm PIR board gives a U-value of around 0.22 W/m²K. It is rigid, easy to cut and fit between studs, and has excellent thermal performance for its thickness. Cost: approximately £25-£35 per m² for 100mm boards.
Mineral wool (Rockwool/Knauf): Cheaper than PIR at £8-£15 per m² for 100mm but requires a vapour barrier and has slightly lower thermal performance (U-value ~0.35 W/m²K at 100mm). Good acoustic insulation if noise is a concern — useful for music studios or therapy rooms.
Multifoil insulation: Thin, reflective insulation that works well in combination with PIR. Useful where wall thickness is limited. Typically adds an extra thermal resistance equivalent to 25-50mm of PIR in just 20-30mm thickness.
Common Insulation Mistakes
No vapour barrier: Without a vapour control layer on the warm side of the insulation, moisture from inside the room condenses within the wall structure, leading to damp, mould and rot. This is the single most common failing in DIY garden room builds.
Floor insulation neglected: Heat loss through an uninsulated floor is significant, especially in winter when the ground is cold. Always insulate the floor to the same standard as the walls — 100mm PIR on top of a damp-proof membrane.
Gaps and bridges: Any gaps in the insulation — around windows, at corners, where services penetrate — create thermal bridges that lose heat and cause condensation. Use expanding foam to seal all gaps and tape all joints in the vapour barrier.
Garden Room Mistakes to Avoid
I have seen a lot of garden room projects go wrong, and the mistakes are almost always the same. Here are the ones that cost the most to fix.
Buying on Price Alone
The cheapest garden room is almost never the best value. A £6,000 timber cabin from a budget supplier might look similar to a £15,000 garden room from a specialist, but the difference in insulation, build quality, window specification and structural integrity is enormous. The budget cabin will be cold in winter, hot in summer, and may develop structural issues within 3-5 years. The specialist build will still be performing perfectly in 20 years. Get three quotes and compare specifications, not just prices.
Ignoring Access
Your garden room needs to be delivered and built. If the only access to your back garden is through the house or via a narrow 600mm side passage, you have a problem. Most modular garden rooms require at least 1.5m-wide access. SIP (Structural Insulated Panel) garden rooms are delivered in large panels that need crane access if there is no wide enough gate. Always measure your access route and discuss it with your supplier before ordering.
Skipping the Electrics Quote
Many people budget for the garden room itself but forget the electrics until the building arrives. Getting a qualified electrician to quote for the cable run, consumer unit and internal wiring before you order the building avoids a nasty surprise. Electrical costs of £1,500-£3,000 can significantly affect your budget.
Not Checking Permitted Development Rules
Assuming your garden room is permitted development without checking the specific rules for your property is risky. If your home is in a conservation area, is a listed building, or if you have already used your permitted development allowance on other outbuildings, you may need planning permission. Getting it wrong can result in an enforcement notice and, in the worst case, being ordered to demolish the building.
Poor Drainage Around the Base
Water pooling around the base of a garden room causes damp, rot and frost damage over time. Ensure the ground slopes away from the building on all sides, and consider installing a French drain or gravel margin around the perimeter. This is especially important on clay soils where water sits on the surface.
What Can You Use a Garden Room For?
The versatility of a garden room is one of its biggest advantages. Here are the most popular uses and the size and specification you need for each.
Home Office
The most popular use since 2020. A comfortable single-person home office needs a minimum of 8m² (e.g. 3m x 2.7m). For two people, aim for 12m² minimum. You need good insulation (year-round use), reliable electrics with multiple sockets, fast internet (via an outdoor ethernet cable or a mesh WiFi extender) and adequate heating. Budget: £15,000-£25,000 for a standard spec.
Art Studio or Workshop
Artists and makers need natural light, so specify larger windows or skylights — ideally north-facing for consistent, glare-free light. A 15m² room gives enough space for an easel, work table and storage. If you work with paints or chemicals, add a small extractor fan. Durable flooring (vinyl or resin) is easier to clean than carpet. Budget: £18,000-£30,000.
Gym or Fitness Room
A home gym needs 12m² minimum — 15m² if you want free weights, a rack and a cardio machine. The key consideration is floor loading: heavy gym equipment needs a concrete slab foundation, not ground screws. Add rubber gym flooring (£20-£30/m²) to protect the structure and reduce noise. Budget: £15,000-£25,000 plus foundation upgrade.
Music Room or Recording Studio
Sound isolation is critical. Standard garden rooms transmit a surprising amount of noise — enough to annoy neighbours at high volumes. For a proper music room, you need either a specialist acoustic garden room (companies like Garden Studios and Studiobricks build these) or acoustic treatment inside a standard room (acoustic panels, bass traps, decoupled walls). Budget: £20,000-£40,000 for a purpose-built acoustic room.
Therapy or Treatment Room
Therapists, counsellors and beauty therapists need a professional, welcoming space with a separate entrance, good lighting and adequate heating. A 10-12m² room is sufficient for most treatments. If you are running a business, check whether you need change-of-use planning permission and whether your home insurance covers business use of an outbuilding. Budget: £18,000-£28,000 with a professional interior finish.
| Use | Minimum Size | Key Requirements | Typical Budget |
|---|---|---|---|
| Home office (1 person) | 8 m² | Insulation, electrics, internet, heating | £15,000-£25,000 |
| Home office (2 people) | 12 m² | As above plus more sockets | £20,000-£30,000 |
| Art studio | 15 m² | Natural light, durable flooring, ventilation | £18,000-£30,000 |
| Home gym | 12-15 m² | Concrete slab, rubber flooring, ventilation | £15,000-£25,000 |
| Music/recording studio | 12 m² | Acoustic treatment, sound isolation | £20,000-£40,000 |
| Therapy/treatment room | 10-12 m² | Professional finish, separate entrance | £18,000-£28,000 |
| Garden bar/entertainment | 15-20 m² | Plumbing, bifolds, outdoor area | £25,000-£40,000 |
How to Choose a Garden Room Supplier
The garden room market in the UK has exploded since 2020, and not all suppliers are equal. Here is what to look for and what to avoid.
Questions to Ask Every Supplier
What is included in the price? Some suppliers quote for the building only, while others include foundations, electrics, internal lining and delivery. A £15,000 quote that includes everything is better value than a £12,000 quote that excludes £5,000 of essentials.
What insulation do you use? Ask for the U-value of the walls, floor and roof. Anything above U 0.3 W/m²K will be uncomfortable in winter without heavy heating. Reputable suppliers will be happy to tell you the exact insulation type and thickness.
What guarantee do you offer? A 10-year structural guarantee is the minimum you should expect. Check whether the guarantee is insurance-backed (meaning it is valid even if the company goes bust) or company-backed only.
Can I visit a completed installation? Any supplier confident in their work will be happy for you to visit a completed garden room, preferably one that is 2-3 years old so you can see how it has weathered. If they refuse, be cautious.
How long from order to completion? Lead times vary from 4 weeks (modular, off-the-shelf) to 12-16 weeks (bespoke, architect-designed). Get a firm completion date in writing and check what happens if they overrun.
Red Flags
No fixed address or showroom. Demands for large deposits (more than 10-20% upfront). No written specification or contract. No structural guarantee. Unable or unwilling to provide references. Uses vague terms like "well insulated" without specifying U-values or insulation type. Company less than 2 years old with no track record.