Design and permissions · High risk
Planning permission or permitted development?
Establish the route in writing before drawings are finalised.
- When it lands
- Before you submit anything, and before you invite quotes.
- What it costs to get wrong
- Building without the right consent can mean enforcement, and it will surface on any future sale.
Permitted development is not a loophole; it is a defined set of rules with hard dimensional limits, and it does not apply to every house. Establishing your route in writing before drawings are finalised prevents the most avoidable delay in domestic construction.
Establish the route before you finalise anything
Permitted development rights are restricted or removed in conservation areas, on listed buildings, on flats and maisonettes, on some new-build estates by planning condition, and where earlier extensions have already used up the allowance.
That last one catches people constantly, because the allowance runs with the house, not with the owner. Work a previous owner did counts against you.
A lawful development certificate is cheap proof
If you are relying on permitted development, apply for a lawful development certificate. It is a modest fee and a few weeks, and it produces a document confirming the work was lawful.
A 1970s house had a small side extension added by a previous owner. The new rear extension was built under permitted development with no certificate. On sale, the buyer's solicitor could not establish that the allowance had not been exceeded — the sale stalled while indemnity insurance and a retrospective application were arranged.
Pre-application advice where it is finely balanced
Where a scheme is borderline, pre-application advice from the council gives you a written officer view before you commit to a full application. It costs a few hundred pounds and can save a refusal, a redesign and three months.
Approval is not the finish line
Planning permission controls what the outside looks like and how it affects neighbours. Building regulations control whether it is safe, warm and properly constructed. They are separate approvals and you need both. Planning drawings will not build a house.
Why this one matters
The route changes the design, the timeline and the risk. A lawful development certificate costs little and turns 'we think it's permitted' into something you can prove to a buyer years later.
Do this week
- Confirm in writing which route your project takes.
- If it is permitted development, start the lawful development certificate.
- Check whether previous extensions have used the allowance.
The realistic choices
Permitted development
Faster, but get a lawful development certificate as proof.
Full planning application
Typically 8–13 weeks. Do not book a builder before determination.
Pre-application advice
Worth it where the design is finely balanced or the street is sensitive.
What good looks like
- Written confirmation of the route, not a verbal opinion
- No builder start date committed before consent is in hand
Questions worth asking
- What is our fallback if this is refused?
- Do any conditions have to be discharged before we start?
From real projects
Permitted development that was not
A 1970s house had a small side extension added by a previous owner. The new rear extension was built under permitted development without a certificate. On sale, the buyer's solicitor found the earlier addition had consumed the allowance. Retrospective permission and indemnity insurance delayed completion by three months.
The lesson: Permitted development is a right you have to prove. A lawful development certificate is the proof.
Putting it into practice
What this decision should leave behind
The steps to work through, the paperwork worth keeping and the questions to send your builder today.
- · Establish whether permitted development covers it
- · Consider a lawful development certificate
- · Pre-application advice where it is finely balanced
- · Template: Pre-application advice request
- · Paperwork: Planning decision notice or lawful development certificate
- · Paperwork: Approved planning drawings
Next decision
Does a party wall notice apply?