Planning approval rates sound like a simple statistic. But in Harrow, the answer to "will mine get approved?" is almost entirely dependent on factors most homeowners haven't even thought to check. If you want to skip the guesswork, WhatCanIBuild shows you what's actually been approved and refused near your address — and what that means for your specific project.
The short version
- Harrow's approval odds vary dramatically by property, street, and project type
- Conservation areas, Article 4 directions, and Green Belt land all shift the odds — and you may not know which apply to you
- A householder application in Harrow currently costs £258 and typically takes 8 weeks to decide — that's a lot riding on an uncertain outcome
The borough-wide picture tells you almost nothing
National planning statistics track application volumes and decisions across England. What they don't tell you is whether your type of project, on your street, in your part of Harrow, tends to sail through or get knocked back. Harrow is not a uniform place. The rules — and the outcomes — in HA1 look different from HA3, and even two properties on the same road can sit in completely different planning contexts. Most homeowners don't realise just how localised this gets.
Harrow has more constraints than most people expect
Harrow has Green Belt land in the north, including around the Bentley Priory nature reserve. It has multiple conservation areas — Pinner, Stanmore, Canons Park among them — many of which carry Article 4 directions. There are listed buildings scattered across the borough. There's a Tall Buildings SPD, a Residential Design SPD, and garden land policies that affect what you can build and where.
Each of these layers changes the planning calculus in ways that aren't obvious from the outside. Being in a conservation area is one thing. Knowing what that actually means for your proposed rear extension, loft conversion, or outbuilding — that's something else entirely.
Check before you assume
Harrow's Article 4 directions remove certain permitted development rights in specific areas. A project that wouldn't need planning permission elsewhere in the borough might need a full application at your address — and face a different set of scrutiny when it gets there.
What's been refused near you matters more than general guidance
Planning officers look at precedent. If similar applications on your street or in your immediate area have been refused — or approved with conditions — that shapes how yours is likely to be assessed. This is the kind of intelligence that general guidance can't give you. It's also the kind most homeowners never think to look for before submitting.
That's where WhatCanIBuild is genuinely useful — not just flagging whether you're in a conservation area (you can find that on the council's website), but showing you what's actually happened to projects like yours nearby, and how your property's specific combination of constraints affects your realistic approval odds.
So what are your actual chances?
Honestly? It depends on your property. The £258 application fee and 8-week decision window are fixed — but what comes back at the end of that process is not. Submitting without understanding your local context is one of the more expensive guesses a homeowner can make.
Before you apply — or decide you don't need to — the best way to understand your real position is to check what the data says about your specific address. WhatCanIBuild pulls together the planning history, constraints, and approval patterns that actually predict your outcome.
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