Garden Workshop: Size, Base, Power and the Planning Rules

A garden workshop is a shed or outbuilding fitted out for making and mending things: woodwork, bikes, metalwork, pottery or repairs. It looks like a garden room from the outside, but it asks for different things: a floor that can carry a heavy bench and machines, more power than a few sockets, a plan for dust and noise, and serious security, because the contents are often worth more than the building. This page covers the size, base, power, layout and rules for a garden workshop in England, so you can buy or build one that you will still be happy working in five years from now.

We are Best Garden Room, and we cover garden buildings of every kind. If you are building the shell yourself, start with our step-by-step on how to build a garden shed, then come back here for the fit-out.

What size garden workshop do you need?

Work out the size from the longest thing you will cut and the machines you will own, not from the shed brochure. A few rules of thumb from people who use their workshops daily:

Bench and hand tools only (repairs, bike maintenance, small woodwork): an 8×6 shed works, provided the bench runs along the long wall under a window.
A table saw or mitre saw: you need clear space either side of the blade at least as long as the boards you cut. Ripping a 2.4m sheet or length indoors needs well over 5m in one direction, so many people put a door at each end or cut long stock outside.
Several machines plus a bench: 10×8 is a comfortable minimum, and 12×10 or larger stops you moving one machine every time you use another.

Height matters as much as floor area. You want to be able to lift a board overhead without hitting the roof, which is where a tight permitted development height limit can bite (see the planning section below).

Base, floor and walls: built for weight and damp

A woodworking bench, a pillar drill and a bandsaw put concentrated loads on small feet. A standard 12mm shed floor on light bearers will flex and bounce under them, which ruins accuracy and eventually the floor.

Base: a level concrete slab is the strongest option for heavy machinery. A timber frame on ground screws or a paving base can work for lighter use if the bearers are close together. Our comparison of ground screws and concrete bases sets out the trade-offs.
Floor: 18mm or thicker tongue and groove boarding or exterior-grade ply on closely spaced joists, or the bare slab with a sealed finish if you want to bolt machines down.
Walls: at least 19mm cladding if you want to hang tool racks and cupboards. Thin overlap panels will not hold screws for heavy storage.
Insulation: metal tools rust in a cold, damp shed. Insulating the walls, floor and roof, with a vapour control layer on the warm side, keeps condensation off your tools. Our page on insulated garden sheds explains the build-up.

Power and lighting

An extension lead from the house is not a workshop supply. Saws and dust extractors draw heavy current at start-up, and a trailing lead is a trip, a crush and a water risk.

In England, Part P of the Building Regulations makes the installation of a new circuit notifiable, and running a new supply out to a garden building counts. That means either a registered electrician who self-certifies the work under a competent person scheme, or a building notice to your council before you start. Typical requirements for a workshop supply include a suitably sized armoured cable from the house, a small consumer unit in the workshop with RCD protection, and enough double sockets along the bench that you never daisy-chain adaptors. Our garden room electrics page covers the cable route and what an electrician will ask you.

For lighting, bright, even LED battens over the bench and the machines beat a single central fitting, because they cut the shadows your own body throws on the work. Add natural light from a window over the bench if the plan allows.

Dust, noise and ventilation

Wood dust is the health risk most hobby workshops ignore. The Health and Safety Executive says both softwood and hardwood dusts can cause asthma and other respiratory problems, and that hardwood dust can cause a rare form of nasal cancer. Its wood dust guidance is written for workplaces, but the controls translate directly to a garden workshop:

Connect a dust extractor or a workshop vacuum to every power tool that has a port.
Clean up with a vacuum, not a broom, and never blow dust off with compressed air.
Wear a properly fitted dust mask rated for fine dust when sanding or cutting.
Give the building cross ventilation: an opening window plus a vent low on the opposite wall.

Noise is the other problem, and this one is about your neighbours. Councils can treat noise from premises as a statutory nuisance under section 79 of the Environmental Protection Act 1990, and “unreasonable DIY” is on many councils’ lists of things they investigate. Insulation helps a lot with sound as well as heat. Beyond that, keep loud machine work to reasonable daytime hours and site the door and windows away from the nearest bedroom.

Layout and storage

Good workshops are planned around a workflow: material comes in the door, gets cut, gets assembled on the bench, gets finished, goes out. Put the saw near the door, the bench in the best light, and the finishing area as far from the dust as possible.

Screwdrivers and pliers held upright in a timber rack along the back of a workbench — A simple timber tool rack along the back of a bench keeps screwdrivers and pliers visible and off the worktop. | Tool rack by 1lenore (CC BY 2.0), via Flickr, https://www.flickr.com/photos/80522246@N00/2515800654

Bench height: a common starting point is roughly the height of your wrist with your arm hanging by your side, higher for fine work, lower for planing.
Walls first: French cleats or pegboard keep tools visible and the floor clear.
Mobile bases: machines on lockable wheels let a small workshop do the work of a large one.
Flammables: keep finishes, solvents and oily rags in a closed metal container, away from heaters. Oily rags from some finishes can self-heat, so lay them flat outside to dry before disposal.

Security: the tools are the target

A garden workshop with power tools is one of the most attractive things in a garden to a burglar. Treat it like a building, not a shed.

Fit a solid door with proper hinges and a five-lever or high-security padlock and hasp, with the screws hidden or replaced with security fixings.
Use frosted film or blinds so tools cannot be seen from outside.
Add a battery alarm or a camera, and ground anchors for anything expensive that can be carried.
Photograph serial numbers and check whether your home insurance covers outbuilding contents, and to what limit.

Do you need planning permission or building regulations?

Most garden workshops are permitted development, so they need no planning application, as long as the building stays within the Planning Portal limits for outbuildings. The key ones are: single storey; no more than 2.5m eaves height; overall height no more than 4m with a dual pitched roof or 3m for any other roof; no more than 2.5m high if within 2m of a boundary; nowhere forward of the front wall of the house; and no more than half the land around the original house covered by buildings. Listed buildings and designated land have tighter rules. Our page on planning permission for a garden shed goes through each one.

The use matters too. Permitted development covers buildings used for purposes incidental to enjoying the house, which takes in a hobby workshop. The Planning Portal says it does not cover any professional use, so if you plan to run a business from the workshop, with customers, staff or deliveries, ask your council before you build.

For building regulations, Schedule 2 of the Building Regulations 2010 exempts a detached building with no sleeping accommodation if it is under 15m², or up to 30m² if it is at least 1m from the boundary or built substantially of non-combustible materials. The electrics are the exception: Part P still applies to a new circuit, whatever the size of the building.

Frequently asked questions

Can I use a shed as a workshop?

Yes, and most garden workshops start as sheds. The upgrades that matter are a stronger floor, thicker walls to hang storage on, insulation to stop tools rusting, a proper electrical supply and better locks.

Do I need planning permission for a garden workshop?

Usually not, if it is for hobby use and stays within the permitted development limits for height, position and coverage. Professional use, a listed house or designated land can all mean you need permission.

Can I run electricity to a garden workshop myself?

In England a new circuit to an outbuilding is notifiable under Part P. You can do it yourself only by submitting a building notice to the council before you start and having the work inspected. Most people use a registered electrician who can self-certify it.

What is the best floor for a garden workshop?

For heavy machines, a concrete slab. For hand tools and light machines, 18mm or thicker boarding on closely spaced joists works, ideally with insulation underneath.

How do I stop tools rusting in a garden workshop?

Insulate the building with a vapour control layer, ventilate it, and keep it slightly heated in winter. A dehumidifier helps in a sealed building, and a light coat of oil or wax on cast iron tables protects them between uses.