Do I need planning permission for a shed? The size rules

The rules that let most sheds go up without an application

Sheds, summerhouses, greenhouses and garden offices in England fall under Class E of the householder permitted development rights, in Schedule 2, Part 1 of the General Permitted Development Order 2015. A building that meets every one of the conditions needs no planning application. One that breaks any of them does.

• It must be single storey, with no veranda, balcony or raised platform more than 0.3m high.
• No part of it may sit forward of the principal elevation, which is usually the front of the house facing the road.
• Together with every other outbuilding, extension and container added since the house was built, it must not cover more than half of the land around the original house.
• It must be used for something incidental to enjoying the house: storage, a workshop, a hobby room or a home office. A bedroom, bathroom or kitchen used as primary living space is not incidental and needs permission.
• Containers for heating oil or LPG are capped at 3,500 litres.

The height limits

Height is the limit that decides most cases, and it is measured from the highest ground level immediately next to the building, which matters on a slope.

The 2 metre rule catches most garden offices. A pent roofed building tucked into the back corner of a typical garden must stay at 2.5m or under at its highest point, including the roof, not just the walls. Most off the shelf sheds are made to sit under that figure; for larger summerhouses and log cabins, the overall height is worth checking.

When a shed does need permission

Several situations remove the automatic right altogether or tighten it:

• Listed buildings. Any outbuilding within the grounds of a listed building needs planning permission.
• Flats and maisonettes. Householder permitted development rights do not apply, so any shed needs an application.
• Conservation areas. Nothing may be built between a side wall of the house and the boundary.
• National Parks, Areas of Outstanding Natural Beauty, the Broads and World Heritage Sites. Outbuildings more than 20 metres from the house are limited to 10 square metres in total.
• Removed rights. Councils can withdraw permitted development rights with an Article 4 direction, and some newer estates had them removed by a condition on the original planning permission.

A Lawful Development Certificate from the council confirms in writing that a proposed shed is permitted development. It is optional, but useful for a large garden building and helpful when the house is sold.

Building Regulations are a separate question

Planning decides whether a building may exist; Building Regulations govern how it is built. Schedule 2 of the Building Regulations 2010 exempts most garden buildings in England.

• A detached building of no more than 15 square metres floor area, with no sleeping accommodation, is exempt.
• A detached single storey building of up to 30 square metres, with no sleeping accommodation, is exempt if no part is within 1 metre of the boundary or it is built substantially of non combustible materials.

A timber garden office of 25 square metres built hard against the fence therefore needs Building Regulations approval even if it needs no planning permission. Electrical work run out to a shed is a separate matter again and needs a competent electrician.

Scotland and Wales

The figures above are for England. Scotland sets its own allowances in Class 3A of its householder permitted development rules: a maximum height of 4m with eaves of 3m, no more than 2.5m for any part within 1 metre of a boundary, and at least half of the front or rear garden left undeveloped, with tighter limits in conservation areas and for listed buildings. A building warrant may also be needed. Wales and Northern Ireland have their own rules, and the local council's planning team is the place to check.

Getting the base right

A shed lasts as long as the base under it stays level and dry. A small timber shed can sit on a plastic grid or timber frame laid on firm, level ground. A typical garden shed is better on paving slabs bedded on a compacted sub-base, and a large workshop, garden office or anything carrying heavy machinery wants a concrete slab on compacted hardcore.

The base needs to be level in both directions, sit clear of where water collects, and leave enough room around the shed to reach the walls for treating and repairs. The landscaper who lays a patio can often build the base too, and asking where the spoil will go and what sub-base depth is included makes two quotes easy to compare.