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Garden room kits and self-build

A self-build kit is the cheapest way to get a garden room, but the price on the box is rarely the whole cost. Here's what to check before you buy, and when an installed room is worth the extra.

Updated 22 October 2026

A timber garden hut with a round window among greenery

The short answer: a self-build kit can save a lot on the building itself, with small kits from around £1,500 to £2,500 for materials, against £8,000 to £15,000 for an installed modular room.¹ But you take on the base, the build and the finishing, and the electrics still need a registered electrician.²

What's usually in a kit

Kits vary widely, so read the specification line by line. Many include the walls, roof, doors and windows, but not the base, insulation, interior lining, flooring, guttering or electrics. Two kits at the same price can leave you very different amounts of work and cost.

Item	Ask whether it's included
Base or foundations	Usually not. Budget separately.
Insulation for floor, walls and roof	Often optional or extra.
Glazing	Check it's double glazed, not single.
Roof covering	Felt, EPDM rubber or shingles? Rubber lasts longest on flat roofs.
Interior lining and flooring	Often extra.
Electrics	Never DIY: needs a registered electrician.

What self-build really costs

The kit is only part of the bill. Add the base (ground screws cost around £30 to £50 per m², a concrete slab £80 to £120 per m²), insulation, the electrical connection (£800 to £1,500 for a basic supply) and finishing materials.¹ Use the cost calculator to compare the total with an installed room.

Can you build it yourself?

If you're comfortable with a long weekend of careful carpentry and have a second pair of hands, most kits are manageable. The parts people struggle with are getting the base perfectly level, fitting insulation without gaps, and making the roof watertight. Those are also the parts that decide whether the room is warm and dry for years. Some people build the shell themselves and pay a professional for the base and the roof.

A small log cabin with a green door and window — Kits range from simple log cabins to fully insulated garden rooms.

The rules still apply

Planning: a kit is treated exactly like any other outbuilding. Check the height and position rules with the planning checker.
Building regulations: the 15m² and 30m² thresholds apply as normal.³ See the building regulations guide.
Electrics: running power to the room is notifiable work in England, so it must be done or signed off by a registered electrician.²

Kit or installed: how to decide

	Self-build kit	Installed garden room
Cost of the building	Much lower	Higher, but usually includes the base and installation
Your time	Several days to weeks	Usually installed in days
Insulation and finish	Up to you	Set by the company's specification
Guarantee	Materials only	Usually covers the whole build

If the room is for occasional use or storage, a kit is often the sensible choice. If you'll work in it every day, a well-insulated installed room is usually worth the extra.

Questions people ask

How much does a garden room kit cost?

Small self-build kits start from around £1,500 to £2,500 for materials. Larger insulated kits cost much more, and you'll also need a base, insulation and electrics.¹

Can I wire a self-build garden room myself?

In England, adding a new circuit is notifiable work. Unless building control inspects it, it must be done and certified by a registered electrician.²

Do garden room kits need planning permission?

The same rules apply as for any garden room. Most don't, if they stay within the height and position limits.⁴

Related guides

A garden path leading to a small building at the bottom of the garden

FoundationsGetting the base right.

A cosy timber room with a sofa, lamp and glass doors onto a deck

InsulationThe part of a kit most worth upgrading.

A white timber garden building with French doors and a red roof

Garden room costsCompare a kit with an installed room.

Sources

MyBuilder, Garden room cost price guide, updated 21 October 2026. UK price ranges for garden rooms, foundations, electrics, plumbing and fees.
Homebuilding & Renovating, What is Approved Document P?. Explains when electrical work in England is notifiable.
Planning Portal (England), Outbuildings: building regulations. When building regulations normally apply to outbuildings.
Planning Portal (England), Outbuildings: mini guide. Permitted development limits for outbuildings.