How the Mayfair Studio Planning Checker Works: What 90 Seconds of Analysis Actually Includes
The UK's most comprehensive free planning checker cross-references 9 million planning decisions, every conservation area, every Article 4 direction, and every London borough's policy documents in under two minutes. Here's exactly what it checks.
Most free planning checkers in the UK are little more than a checklist: a set of questions about your project that map to permitted development rules. They tell you whether most projects like yours would need permission. They don't know anything about your property.
The Mayfair Studio planning checker is different. It reads the same public data that planning officers use, for the exact property at the address you enter. No guessing. No generic advice. A written report tailored to your home.
This guide walks through what the checker actually does - what it looks at, what it returns, and what it can and cannot tell you.
What the checker looks at
For every property you check, the system pulls data from more than ten official UK sources. This is the same underlying data a planning consultant would read if you paid them £1,500 for a feasibility report. The difference is we read it all in 90 seconds, for free, and present it in plain English.
Data sources (non-exhaustive)
- 1.planning.data.gov.uk - every historic planning application in England since 2005, including decisions, dates and conditions
- 2.Ordnance Survey Places + OS Open - UPRN-verified address matching, so the check runs on your exact property, not just the postcode
- 3.Historic England registers - every listed building, scheduled monument and registered park in England
- 4.Conservation area boundaries - the full national dataset, refreshed from planning.data.gov.uk
- 5.Article 4 direction registers - every borough's list of removed permitted development rights
- 6.Tree Preservation Order registers - protected trees on and around your property
- 7.Environment Agency flood risk - Zone 1, 2, 3a and 3b classifications for your exact plot
- 8.HM Land Registry - house price trends and transaction data for your street
- 9.EPC register - energy performance data that affects what you can add and how
- 10.BCIS and regional cost indices - realistic build costs by London borough, house type and specification
- +Every London borough policy document - 32 local plans, supplementary planning documents, design guides, and article 4 schedules, indexed and searchable
Most free tools stop at step 1 or 2. Paid consultancy reports typically cover steps 1 through 6. The Mayfair Studio checker reads all eleven, plus the 32 London borough policy documents, in one pass.
The checks it runs
Once the data is loaded, the checker runs through a structured set of questions about your project. Every answer is based on the data for your specific property - not generic averages.
1. Is the property in a sensitive area?
Checks conservation area status, listed building status, Article 4 directions, National Parks, Areas of Outstanding Natural Beauty, and flood zones. These are the first things that can remove permitted development rights.
2. What type of property is it?
Detached, semi-detached, terraced, end-of-terrace, flat, maisonette or non-residential. Permitted development rules are completely different for each type, and the checker maps the OS property data to the correct category automatically.
3. Does your project fit permitted development?
Checks the specific measurements and constraints of the General Permitted Development Order 2015 against your project details. Depth, height, eave height, materials, volume - all the rules that determine whether you can build without planning permission.
4. What's the historic approval rate for this type of project here?
This is where the 9 million planning decisions come in. The checker finds every historic application in your borough for projects like yours and calculates the actual approval rate - not the national average. A rear extension in Camden has a very different approval rate from one in Bromley.
5. What's the right planning route?
Based on the constraints and your project type, the checker recommends one of: Lawful Development Certificate, Prior Approval, Householder Planning Application, Full Planning Application, Listed Building Consent, or Change of Use. Each route has different costs, timelines and risk levels.
6. What will it realistically cost to build?
Using BCIS build cost indices and real recent construction data for your area, the checker estimates the likely build cost range for your project. Not a headline national average - your borough, your house type, your project size.
7. What's the realistic timeline?
Determination time varies enormously by borough. Some London councils average 8 weeks for householder applications; others routinely take 14 weeks. The checker uses actual decision dates from the historic data for your specific council.
8. What should you do next?
The final section of the report is a plain-English action plan: what to apply for, what surveys you might need, what drawings are required, and whether Mayfair Studio can deliver the full package for a fixed fee.
How it compares to alternatives
| Approach | Cost | Time | Data sources |
|---|---|---|---|
| Mayfair Studio checker | Free | 90 seconds | 10+ sources, reviewed by our planning team |
| Planning consultant report | £750 - £2,000 | 3 - 10 days | Same sources, manually researched |
| Council pre-application advice | £100 - £500 | 4 - 6 weeks | Council records only |
| Free PD checker (other tools) | Free | 1-2 minutes | PD rules only, no property-specific data |
| DIY research | Free | 5 - 20 hours | Whatever you can find manually |
- Cost
- Free
- Time
- 90 seconds
- Data
- 10+ sources, reviewed by our planning team
- Cost
- £750 - £2,000
- Time
- 3 - 10 days
- Data
- Same sources, manually researched
- Cost
- £100 - £500
- Time
- 4 - 6 weeks
- Data
- Council records only
- Cost
- Free
- Time
- 1-2 minutes
- Data
- PD rules only, no property-specific data
- Cost
- Free
- Time
- 5 - 20 hours
- Data
- Whatever you can find manually
The checker isn't meant to replace a chartered planning consultant for complex projects - it's meant to give you the answer for routine projects instantly, and flag the complex ones so you know to get proper advice before spending money.
What it can't do
Honest scope limits are important. The Mayfair Studio planning checker is very good at the routine 80 percent of residential projects in London. It's not a replacement for professional advice on:
- Grade I and Grade II* listed buildings
- Basements deeper than one storey
- Projects in the City of London financial district
- Large-scale developments over £500k build cost
- Commercial-to-residential conversions over 2,500m²
- Anything requiring an Environmental Impact Assessment
For any of the above, the checker will tell you clearly that you need specialist advice, and - where possible - suggest a named chartered practice that can help.
Is it really free?
Yes. There is no trial, no freemium tier, no email gate. You enter your address, get your report, and that's it. No sign-up, no data capture, no marketing emails unless you actively ask us to quote for the drawings.
Mayfair Studio makes money the traditional way: if you want us to produce the architectural drawings and submit the planning application, we do that for a fixed fee starting at £1,295. That's typically about half of what a traditional consultant-plus-architect setup would cost.
The checker stays free because it's our marketing - the best way we know to show homeowners that Mayfair Studio knows what it's doing before they commit any money.
Frequently asked questions
Does the checker need my email address?
No. You can run the full check and see the full written report without entering an email. You only share contact details if you want Mayfair Studio to quote for the drawings.
Is the checker available outside London?
Yes. The checker runs on any English postcode. London coverage is deepest because we've indexed all 32 borough policy documents, but the underlying national datasets cover every property in England.
Who reviews the results for complex projects?
Complex projects are flagged and reviewed by our senior planning team before the report is delivered. Routine projects - single-storey extensions, loft conversions, garden rooms - are delivered instantly.
How is this different from other free planning tools?
Most free tools only apply permitted development rules to a short form. They don't look at historic approval data, borough-specific policies, conservation area boundaries at property level, or realistic build costs. The Mayfair Studio checker does all of that in one pass.
What if the checker gets something wrong?
If you go ahead with a Mayfair Studio drawings package and we later identify an issue the checker missed, we revise the drawings at no additional cost. The free check is general guidance; the drawings package comes with a professional review.