How do I prove I did not need planning permission?

There is a gap between believing you are within permitted development and being able to prove it, and the gap only becomes visible years later when somebody is buying your house. The certificate exists to close it. It costs a fraction of a planning application and a tiny fraction of the cost of arguing about it during a sale.

What you'll need

• The property address and its planning history
• Scale drawings — existing and proposed, plan and elevation
• A location plan and a site plan
• Photographs of the existing building (optional)
• A written statement explaining which permitted development class applies

Step by step

1. Decide which kind of certificate you need.One for proposed work, applied for before you build, and one for work already carried out, which relies on evidence that it was lawful or has become immune from enforcement. Scotland uses a certificate of lawfulness of use or development for the same purpose.
2. Identify the permitted development class you are relying on.The application is not a request for permission; it is an assertion that permission is not required, and it must say why. Name the class and explain how the proposal meets each of its conditions.
3. Get drawings made to scale.Existing and proposed, plans and elevations, a location plan and a site plan, all properly scaled and dimensioned. A certificate is decided on what the drawings show, so vague drawings get refused.
4. Describe the original house, with evidence.Because the limits are measured from the original building, show what it was — historic mapping, old photographs, previous planning applications, or the estate layout drawing.
5. Apply through the planning portal or the council directly.The application is made to the local planning authority with the fee. Fees change, so take the figure from the council's current fee schedule rather than from an article.
6. Expect a determination rather than a negotiation.The council decides on the legal facts, not on whether the scheme is attractive or whether neighbours object. Neighbours are generally not consulted, because planning merits are not the question.
7. Build exactly what the certificate describes.The certificate protects the scheme it describes and nothing else. Changing a dimension on site, however slightly, can put the work outside the certificate and outside permitted development at the same time.
8. File it with the deeds.With the drawings the council stamped. This bundle, plus the building control completion certificate, is what makes the work uncontroversial on a future sale.

Tips

• A refusal is genuinely useful information. It tells you before you build that the scheme needs planning permission, which is far cheaper to learn now than after the foundations.
• If work has already been done and you are unsure of its status, take advice before contacting the council — the options and their consequences differ, and an approach cannot be withdrawn.
• The certificate says nothing about building regulations. You still need the completion certificate or the scheme certificate for the construction itself.

Common mistakes

• Relying on a planning officer's email instead — Informal advice is an opinion and expressly does not bind the council. It is worth having early, and it is not what a conveyancer will accept.
• Building something slightly different from the certified drawings — The certificate ceases to describe what exists. You are then back to arguing the general permitted development conditions, without the protection you paid for.

Questions people ask