Lawful development certificate for a garden room

What it is

GOV.UK describes a lawful development certificate (LDC) as a decision from the local planning authority on whether a use or development is lawful for planning purposes. The certificate is evidence. It is not planning permission.

There are two types.

• Existing. Confirms that something already built or in use is lawful.
• Proposed. Confirms that a use or building you plan would be lawful. Once granted, GOV.UK says the proposal is presumed lawful unless there is a material change before it begins.

For a garden room you plan to build, the proposed type is the one to use.

When it is worth applying

• You are close to a limit, such as the 2.5 m height within 2 m of a boundary. See garden rooms near a boundary.
• You are on designated land. See conservation areas and the Chilterns and Green Belt.
• You may sell or remortgage, and want a paper record for a buyer or solicitor.
• The council says an Article 4 direction or an old condition might apply, and you want it settled.
• You want to use the room for a business or a guest, and want the use confirmed. See garden annexe rules.

If your room is clearly inside the permitted development limits, you may not need one. Councils such as St Albans say that for formal confirmation that no planning permission is needed, you can apply for a certificate of lawfulness of proposed development.

How to apply

• Anyone can apply to the local planning authority. You, or someone acting for you, completes the form.
• Include the relevant fee.
• Include sufficient factual information and evidence for the council to decide. For a garden room that means a site plan, elevations with heights, the floor area, the distance to each boundary, and the proposed use.
• Describe the building precisely. GOV.UK says the description must be precise, not just a use class.

The GOV.UK page gives no fee or decision time, so ask your council. Many builders and architects prepare the drawings for you.

What a certificate does not do

• It does not grant planning permission.
• It does not replace building regulations. See building regulations for garden rooms.
• It does not cover listed building consent or other legal needs.
• It only covers what you described. If you change the design, the answer may change.

If it is refused

GOV.UK says a refusal is not necessarily conclusive that something is not lawful. It may just mean the evidence was not enough. You can apply again with more information. The authority can also issue a certificate for a different description, ideally with your agreement. In certain circumstances you can appeal.

A refusal often tells you to make a full planning application. Read the planning permission guide.

Certificate or full planning application?

The two answer different questions. A certificate asks: is this lawful as it is? A planning application asks: should the council allow this? If your room fits inside the permitted development limits, the certificate is the right route. If it does not, for example it is taller than the limit near a fence, a certificate will not help. You need a planning application, and a builder or architect can prepare it.

Some homeowners apply for a certificate before they sign a building contract. That way the contract can rely on a written council answer, not on a guess. Others skip it and rely on the permitted development rules. Both are lawful routes. The choice is yours.

Your council

Your council depends on where you live. Berkhamsted and Tring are in Dacorum. St Albans has its own council. Aylesbury is in Buckinghamshire Council. Each publishes how to apply. Prices for the room itself are in the garden room cost calculator and how a price is built. See also garden studios and garden offices.

Common mistakes

• Applying with thin drawings. The applicant must supply enough evidence for the council to decide.
• Describing the use loosely. Say what the room is for, such as a home office used by the household.
• Changing the design afterwards. The certificate covers what you described.
• Waiting too long. If a material change happens before work begins, the presumption of lawfulness may not hold.
• Forgetting building regulations. The certificate does not remove that need.

A good builder will tell you early if your design is close to a limit. Ask them to check before you apply.