Garden Rooms

What Is a Garden Room?

A garden room is a standalone, insulated building in your garden designed for year-round use as a home office, studio, gym or additional living space. Unlike a shed or summer house, a properly built garden room has full insulation, double or triple glazed windows and doors, mains electrical supply, heating, and interior finishes to the same standard as a room inside your house. MTD Building Contractors build bespoke garden rooms using timber frame or structural insulated panels (SIPs), designed to suit your garden, intended use and budget.

Garden Room Costs

A bespoke garden room typically costs between £20,000 and £50,000 depending on size, construction method and specification. A compact 3m × 3m home office starts from around £15,000–£20,000. A larger 5m × 4m garden room with bi-fold doors, underfloor heating and high-specification internal finish is typically £35,000–£50,000. Costs include foundations (concrete slab or screw piles), the structure, roof, insulation, electrical supply (run from the main house), interior plastering or lining, lighting, heating and decoration. Plumbing for a WC or kitchenette adds approximately £3,000–£5,000. The total cost depends heavily on the distance from the main house (affecting electrical and plumbing runs) and the level of interior finish.

Planning Permission for Garden Rooms

Most garden rooms fall under permitted development rights and do not require planning permission, provided they meet the following conditions: the building is single storey with a maximum eaves height of 2.5 metres and an overall ridge height of 4 metres (3 metres if within 2 metres of a boundary), it is not forward of the principal elevation of the house, and the total area of outbuildings does not exceed 50% of the garden. Properties in conservation areas, listed buildings and some designated areas have more restrictive rules. Building regulations do not normally apply to detached garden buildings under 15 sqm, but buildings over 15 sqm or those with sleeping accommodation may require building regulations approval. MTD Building Contractors check all requirements before work begins.

Construction Methods

We offer two main construction methods for garden rooms. Timber frame with external cladding (larch, cedar or composite) is the most popular option, providing a warm, contemporary aesthetic with excellent thermal performance. SIPs (structural insulated panels) offer rapid construction and very high insulation values. Both methods include breathable membrane, high-performance insulation (typically 100mm+ in walls, floor and roof), and vapour barriers to prevent condensation. Foundations are usually a concrete slab or screw piles depending on ground conditions.

How Long Does It Take to Build a Garden Room?

A typical garden room takes 4–8 weeks from groundworks to completion depending on size, complexity and specification. The foundation stage takes 2–4 days, the structure and weathertight shell takes 1–2 weeks, and the internal fit-out (electrics, insulation, lining, floor, decoration) takes 2–3 weeks. Electrical connection from the main house is carried out by a qualified electrician and takes 1–2 days. We provide a detailed programme at the start of every project and aim to minimise disruption to your garden during construction.