Small garden buildings have one thing in common: we often pick them from a catalogue, at the size of the kit on offer, then look for somewhere to put them. The reverse works better. List what you want to store or shelter, work out the size, find the spot on the plan, and only then look at what the rules allow.
This guide covers the three most common cases: the garden shed, the carport and the pergola. The planning rules are covered in broad terms: they vary between the four nations and Ireland, and your council has the final word.
Start from what goes inside
Measure what's going in, not just what's there today. A few common footprints:
| Item | Footprint |
|---|---|
| Push lawnmower | about 0.60 × 1.50 m, handle unfolded |
| Ride-on mower | about 1.00 × 1.80 m |
| Adult bike | about 0.60 × 1.80 m, hung or standing |
| Wheelbarrow | about 0.70 × 1.50 m |
| Garden furniture stacked for winter | 1.00 × 1.00 m to 1.50 × 2.00 m |
| Long-handled tools | 30 cm of wall, 1.80 m high |
| Small car | about 1.80 × 4.10 m without mirrors |
| Family car or SUV | about 1.90 × 4.70 m without mirrors |
For a shed, add a 70 to 80 cm walkway down the middle: without it, you have to take everything out to reach the back. For a carport, add room to open the doors, at least 70 cm on the driver's side.
Sizes that work
| Building | Use | Common sizes |
|---|---|---|
| Small shed | tools, push mower | 2 × 2 m (4 m²) |
| Medium shed | mower, two bikes, wheelbarrow, tools | 2.50 × 3 m (7.5 m²) |
| Large shed or workshop | all of the above, a workbench | 3 × 4 m (12 m²) |
| Single carport | one car | 3 × 5 m minimum, 3.50 × 5.50 m comfortable |
| Double carport | two cars side by side | 5.50 × 5.50 m minimum, 6 × 5.50 m comfortable |
| Pergola | table for six and its chairs | 3.50 × 4 m |
| Pergola | garden sofa set | 3.50 × 3.50 m |
For height, a carport has to clear the tallest vehicle in the household, roof box included. A clear height of 2.20 m is enough for a car, not always for a van. Under a pergola, allow at least 2.20 m below the beams so it doesn't feel oppressive.
Example. A family with a push mower, three bikes, a wheelbarrow and a six-chair garden set: bikes on the back wall (1.80 m), mower and wheelbarrow side by side (1.30 m), the set stacked in a corner, a walkway in the middle. A 2.50 × 3 m shed just works; 3 × 3 m leaves some room for what you'll buy in the next few years.
Where to put them
The garden shed
- Reachable by a path you can use with a wheelbarrow, even in winter. A shed at the bottom of a soggy lawn only gets used in summer.
- On flat, dry ground, away from low spots where water collects.
- Not under a large tree, which dirties the roof and whose roots lift the base.
- Not over a buried service, a septic tank, a drainage field or the lid of a rainwater tank. The guide mapping underground pipes and cables helps you check.
- Seen or hidden, your choice: from the living room, a well-placed shed closes off a view; badly placed, it's the first thing you see.
The carport
- In line with the entrance, with an easy manoeuvre. Draw the car's path on the plan: reversing in from the road takes more room than you'd think.
- Close to the door of the house you actually use, with a sheltered path if possible.
- With a fall that takes water to the road or a soakaway, not to the house.
- With the future in mind: a charging point, storage at the back, enclosing it as a garage one day. That last one often changes the rules.
The pergola
- On the patio or next to it, where the sun really bothers you: usually to the south or west. The guide patio size and design helps you place the table and the sofa underneath.
- Attached to the house or freestanding. Attached, it needs a solid fixing to the wall and darkens the room behind. Freestanding, it leaves the wall free but needs four well-founded posts.
- With the rain in mind: a roofed pergola or one with louvres collects rain and drops it at the foot of a post. Plan where it goes.
Boundaries and neighbours
This is what most often sinks a project: the shed or carport you want right up against the fence, when the rules limit what you can build there, or the other way round.
Rules usually take one of these forms:
- A lower height limit close to the boundary.
- A zone where nothing can go, such as in front of the house on the road side.
- A maximum total area of buildings on the plot.
- Fire safety for larger buildings close to the boundary.
Other things come on top of the planning rules. A roof that sheds its water onto the neighbour's land causes trouble: gutters and a downpipe on your side avoid it. A covenant in your deeds may restrict what you can build. Work on or right next to a shared wall can bring in the Party Wall Act in England and Wales.
To measure these distances properly, you need to know where the boundary is. The fence isn't always on it. The guide title plans, aerial photos and measuring your land explains how to find it and how far to trust each source.
Permitted development, planning permission and building regulations
Everything depends on the country, the council, the size and the position. Here's the broad picture, to check every time with your local planning authority.
- Planning in England. According to the Planning Portal at the time of writing, many sheds and other outbuildings are permitted development, without a planning application, if they meet conditions: single storey; eaves no higher than 2.5 m; overall height no more than 4 m with a dual-pitched roof, or 3 m otherwise; no more than 2.5 m high within 2 m of a boundary; nothing forward of the principal elevation of the house; and, with extensions, no more than half the land around the original house covered. In the grounds of a listed building, any outbuilding needs permission, and on designated land (conservation areas, National Parks and so on) buildings at the side of the house do too.
- Building regulations in England. The Planning Portal states that a detached building under 15 m² with no sleeping accommodation normally doesn't need approval. Between 15 and 30 m², the same applies if it's at least 1 m from any boundary or built substantially of non-combustible materials. An attached carport open on at least two sides and under 30 m² normally doesn't need approval either, except for any electrics.
- Carports and pergolas aren't named in the outbuilding guidance. How they're treated depends on the design: freestanding or attached to the house, open or roofed, near a boundary or not. A carport attached to the house can count as an extension. Ask before you buy.
- Elsewhere. Wales, Scotland and Northern Ireland have their own permitted development rules. In Ireland, the planning regulations exempt some garden sheds under conditions of area, height and position; the council can give you a formal declaration on whether your project needs permission.
If you want certainty in England, a Lawful Development Certificate from the council confirms in writing that a project is permitted development. A good habit: take your plan to scale to the council, with the dimensions and distances marked. The answer is quicker and more precise than for a description over the phone.
Slab, pads or foundations
The base depends on the building and the ground:
- Light timber or metal shed: concrete pads, slabs on compacted gravel or a thin slab, as the manufacturer advises.
- Heavier or masonry building: a slab or strip foundations, like a small building.
- Carport and pergola: a concrete footing under each post, sized for the weight and, above all, for the wind trying to lift the roof.
A concrete slab is one more sealed surface. Pads or stabilised gravel let more rain soak into the ground, which helps if your soil drains badly or the council asks for drainage to be dealt with on the plot.
Draw them in Architektor
- The shed: with the Wall tool (W key), draw the four walls by typing the lengths (
2.5m, Enter), set their thickness, then add the door with the Door / window tool (O key). The Room tool (R key) inside gives the usable floor area. For a quick sketch, an area of type “Building footprint” is enough. - The carport: an area of type “Building footprint” for the roof footprint, with the floor surface (concrete, paving). The access from the road is drawn separately, as a “Driveway / parking” area. Draw the car as an “Other” area of 1.90 × 4.70 m to check the manoeuvre and the doors.
- The pergola: an area of type “Other”, named “Pergola”, drawn over the patio on the garden level.
- The distances: add permanent dimension lines (D key) between each building and the boundaries, and between the building and the house. These are the figures you'll be asked for.
- The status “To build” shows the project in red, the existing in grey. An old shed to replace goes to “To demolish”, in yellow.
Try several positions with variants: “Shed bottom left”, “Shed against the garage”. You can overlay them to compare. With a Gemini key, a photo-style render from the garden helps you judge how a shed or a pergola changes the view from the house, keeping in mind it's a mood image.
For an application, export the garden level as a PDF to scale, with the title block, the scale bar and the north arrow. It's a base for the site plan the council asks for; check with them what it must show (heights, materials, location plan). For a quote, share the “Garden and outdoor” link: the supplier measures and pins questions on the plan, without creating an account.