If you Google "planning permission cost," the first number you'll see is the council application fee. For a standard householder application in England in 2026, that's £258. Sounds manageable.
But the application fee is the smallest part of the bill. The actual cost of getting planning permission — from the first sketch to the decision letter — is typically £3,000 to £7,000 for a standard extension. More for complex projects.
Here's where the money goes.
The Full Cost Breakdown
| Item | Typical Cost | Notes |
|---|---|---|
| Planning application fee | £258 | Standard householder rate (England, 2026) |
| Architectural drawings | £1,500 – £4,000 | Existing plans, proposed plans, elevations, site plan |
| Design & access statement | £0 – £500 | Often included in architect's fee; required for some applications |
| Tree survey | £300 – £600 | Required if trees near the development |
| Party wall surveyor | £700 – £1,500 | Required under the Party Wall Act if building near a boundary |
| Planning consultant | £500 – £2,000 | Optional — for complex or borderline cases |
| Heritage / conservation report | £500 – £1,500 | Required for listed buildings or conservation areas |
| Typical total (standard extension) | £3,000 – £7,000+ |
The range is wide because projects vary. A straightforward rear extension on a modern detached house in a permissive council might cost £2,500 all in. A basement extension on a listed terrace in a conservation area could easily exceed £10,000 before a single brick is laid.
The Cost Nobody Mentions: Refusal
Every cost above assumes your application gets approved first time. If it doesn't, you're looking at additional costs that dwarf the original outlay.
A refusal means your architect needs to redesign to address the council's reasons. That's more drawings, more fees, and another application (though resubmissions within 12 months are free of the council's application fee). It also means months of delay — a typical planning cycle is 8 weeks, so a refusal and resubmission can easily add four to six months to your project timeline.
The financial sting of a refusal isn't just the redesign fee. It's the knock-on effect on your building schedule, your temporary living arrangements, and potentially your mortgage offer or contractor availability.
This is why knowing your local approval patterns before you apply is so valuable. Spending a few minutes checking what your council actually approves can save you thousands.
See what gets approved in your council →
How to Keep Costs Down
Check your postcode's approval patterns first. This is the single biggest cost-saver available to you. If your council approves 95% of rear extensions, you can be confident that a sensible proposal will succeed. If they approve 78%, you need to be more careful — and investing in a planning consultant might save you the cost of a refusal. PlanningLens gives you this information for free in 10 seconds.
Get pre-application advice. Most councils offer a pre-application service where a planning officer reviews your plans informally before you submit. It typically costs £100–£300 and gives you an early steer on whether your proposal is likely to succeed. Not every council offers this, and the quality varies, but it's worth considering for marginal cases.
Don't over-specify. If your extension falls within permitted development limits, you may not need planning permission at all. This eliminates the application fee, reduces architect costs (simpler drawings needed for building regs only), and removes the risk of refusal entirely.
Ask your architect what's included. Some architects bundle the planning application, design and access statement, and heritage report into their fee. Others charge separately for each. Clarify this upfront to avoid surprises.
The £79 Shortcut
Before you spend £3,000 to £7,000 on a planning application, there's a much cheaper way to find out if your project is likely to succeed.
The PlanningLens free postcode check shows you your council's approval rate, your ward's approval rate, and comparable decisions near your property — in seconds. If you want the full picture, the £79 Pro Report gives you a 17-page analysis of the 20 nearest planning decisions to your address, ward-specific refusal patterns, and extension-by-extension approval patterns.
For less than the cost of a tree survey, you get a clear picture of whether your application is likely to succeed — before you brief an architect.
Before you spend £5,000+ on drawings
Check your local approval patterns first. The PlanningLens Pro Report analyses real planning decisions near your property — refusal patterns, ward-level data, and extension-by-extension approval rates. Delivered by email in minutes.
Get Your Pro Report — £79 →Is It Worth It?
Planning permission costs money. There's no way around that. But the value it unlocks — in property price uplift, in usable space, in quality of life — almost always exceeds the cost by a large margin. A well-executed rear extension typically adds £20,000 to £50,000 to a property's value. A loft conversion even more.
The real question isn't whether planning permission is worth it. It's whether your specific project, in your specific area, is likely to succeed. Answer that question first, and every pound you spend afterwards becomes a better investment.
Free Postcode Check
See approval rates, refusal patterns, and comparable decisions near your property. Takes 10 seconds.
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