A planning refusal costs months and money — and most are avoidable. Councils assess applications against local policy and the National Planning Policy Framework (NPPF), and the reasons for refusal cluster around the same recurring themes. Address them before you submit and your chances improve dramatically.
The seven most common reasons for refusal
- Loss of light or overshadowing to a neighbour — often tested with the 45-degree and BRE daylight guidelines.
- Overlooking and loss of privacy — new windows facing habitable rooms or gardens.
- Overbearing or dominant impact — a bulky extension looming over a neighbouring property or garden.
- Poor design or being out of character with the street and the existing house.
- Overdevelopment of the plot — too little garden left, or breaching the spirit of the 50% rule.
- Highways and parking — loss of off-street parking or unsafe access.
- Trees, flood risk and protected designations — TPOs, conservation areas and flood zones.
How to de-risk before you apply
- Design to the daylight and privacy guidelines from the start — set extensions back, angle or obscure-glaze windows, respect the 45-degree line.
- Look at what your council has actually approved and refused nearby — recent decisions are the best guide to local attitude.
- Use pre-application advice for anything borderline.
- Keep materials and proportions sympathetic to the existing house.
Know the verdict before the council does
This is exactly what Unformed’s Planning Review is built for: it checks your scheme against permitted-development and NPPF rules, researches how your own council has decided similar cases, and hands back a risk-ranked report of what’s likely to be flagged — and how to fix it — before you submit. For the basics first, see do I need planning permission?
This guide is general information, not legal or planning advice. Planning rules change over time and are applied differently by each local planning authority (LPA). Always confirm the position with your council before starting work. Unformed’s Planning Review gives an AI-assisted risk assessment of a scheme but does not guarantee any planning outcome.