Do I Need Planning Permission?

Summary

We have seen homeowners spend £50,000 on works they later had to undo because planning permission was required and refused. The safest time to answer the planning question is before you build or design – not after enforcement letters arrive. This article is written for one reason: to stop homeowners making irreversible decisions based on assumptions. In our work across Lancashire and the wider North West, the most damaging planning problems we deal with are not complex developments or ambitious schemes. They are ordinary domestic projects that started with a simple belief: “I don’t need planning permission.” By the time that belief is tested, the damage is already done.

The Most Dangerous Planning Assumption

The biggest mistake homeowners make when asking “do I need planning permission?” is believing that online guidance replaces judgement. People search until they find an article, forum post or checklist that supports what they want to hear. Once they see words like “you usually don’t need planning permission”, they stop asking questions. The intention is almost always the same: to save architectural fees and avoid council costs. What rarely gets considered is the cost of being wrong.

A Real Case: £50,000 Spent Before the Question Was Asked

One client came to us after building a large dormer extension to his home. He had not applied for planning permission because he believed the dormer fell within permitted development. The works were completed at a cost of around £50,000.

A neighbour complained. The council investigated and issued an enforcement notice. At that point, the client instructed us to submit a retrospective planning application in the hope that permission could be granted after the fact. The application was refused. The refusal cited the dormer’s design, scale and visual dominance, concluding that it caused harm to the character of the host property, the adjoining paired dwelling and the wider street scene.

The client appealed the decision. The appeal was also dismissed. The inspector agreed that the dormer was an incongruous and dominant roof addition and upheld the council’s decision. The end result was stark: the client faced the prospect of removing a brand-new dormer at enormous financial and emotional cost. At no point did the council consider how much the works had cost or how reasonable the client thought his interpretation was. Planning decisions are not softened by hindsight.

Another Common Scenario: “I Didn’t Know I Needed Planning”

In a separate case, a client converted a property into a house in multiple occupation without applying for planning permission. He assumed that because the building already existed, and because he had seen similar properties nearby, permission would not be required.

Again, enforcement action followed. We prepared and submitted a planning application, which was refused. The refusal was not based on technicalities, but on policy and cumulative impact. The council concluded that, when considered alongside other nearby HMOs, the proposal would harm residential character, contribute to overconcentration, increase population turnover and undermine community stability.

The client appealed. The appeal was dismissed. The inspector agreed that the cumulative effect of similar uses in the area justified refusal and that the proposal conflicted with adopted planning policy. The fact that the use was already operating did not improve its chances. Retrospective planning carries no advantage.

Why These Situations Happen So Often

In both cases, the trigger was the same: selective research. Homeowners read planning advice online that appears clear and reassuring, but which strips out context. Statements like “dormers usually don’t need planning permission” or “internal changes don’t require consent” are only true when very specific conditions are met. Those conditions are rarely tested until a complaint is made or the council becomes involved. Planning permission is not decided by checklists alone. It is decided by policy, judgement and context.

What Actually Determines Whether Planning Permission Is Required

Whether planning permission applies to your project depends far more on where and how than on what. In our experience, the following situations regularly trigger planning control when homeowners least expect it:

Roof alterations, particularly dormers, where scale, position or design materially alters the appearance of the building. Bungalows, where any vertical extension can quickly appear disproportionate. Properties with previous extensions, where permitted development rights have already been used up or removed. Sites affected by planning conditions attached to historic approvals. Areas with a concentration of similar uses, where cumulative impact becomes decisive rather than the individual proposal.

These are not technical loopholes. They are fundamental planning considerations that no online article can fully assess without seeing the site and its history.

Why “I’ll Just Chance It” Is the Most Expensive Strategy

Some homeowners knowingly proceed without clarity, assuming that planning permission can be sorted out later if needed. This is a gamble, not a strategy. Once works are built, the planning system does not become more lenient. If anything, scrutiny increases. Councils assess what has been constructed against policy, not against effort or investment. Retrospective applications are judged as strictly as any other, and appeals fail just as often. When permission is refused at that stage, the options narrow quickly. Alteration, partial demolition or complete removal all become real possibilities.

The Difference Between Advice and Validation

Good planning advice is not about telling you what you want to hear. It is about identifying risk early, while there is still flexibility to change direction. The purpose of asking “do I need planning permission?” is not to find reassurance. It is to establish certainty before decisions are locked in. That certainty cannot be achieved by reading selectively or relying on generalised rules.

The Only Sensible Point to Ask the Question

The safest and most cost-effective time to establish whether planning permission is required is before designs are commissioned and before works begin. At that stage, options are still open. Designs can be shaped to suit policy. Alternatives can be explored. The risk of refusal can be assessed honestly rather than optimistically. Once enforcement becomes involved, control is lost. If you are asking yourself whether planning permission applies to your project, that uncertainty is a warning sign worth taking seriously. In our experience, the cost of finding out properly is insignificant compared to the cost of getting it wrong.