You're about to spend £2,000–£5,000 on architect drawings for an extension you haven't checked will be approved. That's the order most homeowners follow: have an idea, hire an architect, submit an application, and hope for the best. If it gets refused, the drawings are worthless — and you're paying again to redesign.
It doesn't have to work this way. Ten minutes of research before you pick up the phone to an architect can tell you whether your idea has precedent nearby, whether similar proposals have been refused, and whether the council you're dealing with is permissive or strict. That research costs nothing. Skipping it can cost thousands.
The Order Most People Follow (And Why It's Wrong)
Here's how the typical homeowner approaches an extension project:
| Step | What most people do | The problem |
|---|---|---|
| 1 | Have an idea (rear extension, loft conversion, annexe) | — |
| 2 | Hire an architect (£2,000–£5,000) | Money committed before any research |
| 3 | Architect draws up plans based on your brief | Design based on what you want, not what gets approved |
| 4 | Submit planning application (£258) | — |
| 5 | Wait 8 weeks | — |
| 6 | Get refused | £2,500–£5,500 wasted |
The mistake happens at step 2. You've committed thousands of pounds before asking the most basic question: has this type of project actually been approved on my street?
If the answer is yes — several neighbours have similar extensions — your architect can design with confidence, referencing approved precedent. If the answer is no — or worse, if similar proposals have been refused — you need to know that before you're paying an architect to draw something that won't get through.
The Smarter Order
Rearranging the process takes no extra time and costs nothing. Here's what the smarter version looks like:
Search planning decisions near your postcode. Look for your project type — rear extension, loft conversion, annexe — and see what's been approved and what's been refused. This tells you whether the principle is established and what the council's tolerance looks like. Takes 10 minutes. Check your postcode here — free.
Most councils publish supplementary planning documents for householder extensions. These tell you maximum depths, height limits, boundary setbacks, and material requirements. Your architect should know these — but you should too, before you brief them.
Most councils offer a paid pre-application service (£100–£600 for householder schemes). A planning officer reviews your proposal informally and flags likely objections. It's not binding, but it's the closest thing to a preview of the decision — and it's a fraction of the cost of full architect drawings.
When you do brief an architect, you can tell them: "Three rear extensions on my street have been approved at 4m depth, single storey, matching brick. One was refused at 6m depth. Design to 4m." That's a brief based on evidence, not aspiration. Your architect will thank you for it — and your chances of approval go up dramatically.
The difference between these two approaches isn't time or cost. It's information. The first approach hopes. The second approach checks.
Check what gets approved near you — before hiring anyone
See real planning decisions near your postcode. Approval rates, refusal patterns, and comparable decisions from 2,590,000+ applications across 240 UK councils.
Check Your Postcode — Free →What Checking First Actually Saves You
The numbers are straightforward. Here's the cost comparison between checking first and not checking:
| Scenario | Cost |
|---|---|
| Check first, then hire architect | |
| Planning research (PlanningLens or council portal) | £0–£19 |
| Pre-application advice (optional) | £100–£600 |
| Architect drawings (informed brief) | £2,000–£5,000 |
| Planning fee | £258 |
| Total (high confidence of approval) | £2,358–£5,877 |
| Hire architect first, get refused, redesign | |
| Architect drawings (first attempt) | £2,000–£5,000 |
| Planning fee (first attempt) | £258 |
| Revised drawings after refusal | £1,500–£3,000 |
| Planning fee (resubmission within 12 months) | £0 |
| Total (if second attempt succeeds) | £3,758–£8,258 |
The "check first" route costs less and takes less time — even if you pay for pre-application advice. The "hire first" route costs more, takes months longer, and still might not work if the redesign doesn't address the fundamental objections.
And if the research tells you the project isn't viable? You've saved the entire architect fee. That's £2,000–£5,000 you didn't waste on drawings for something that was never going to be approved.
See what's been approved on your street before you brief an architect →
What to Look for Before You Brief an Architect
When you're checking nearby decisions, you're looking for specific things that will shape your brief. Here's what matters most:
1. Has your project type been approved nearby?
If you want a rear extension and three neighbours already have one, the principle is established. Your architect can design with confidence. If nobody on the street has extended, your application is the test case — which means harder scrutiny and higher risk.
2. What size and scale gets approved?
Look at the approved extensions near you. Are they 3m deep or 6m? Single storey or two? Flat roof or pitched? These details tell you the council's comfort zone. Brief your architect to design within it, not beyond it.
3. What gets refused — and why?
Refusal reasons are more valuable than approval reasons. If a two-storey rear extension was refused for "harm to the amenity of the neighbouring property through loss of light," your two-storey proposal on the same street will face the same objection. A single-storey design might not.
4. How strict is your council?
Councils vary enormously. Some approve over 90% of householder applications. Others refuse more than 1 in 4. If your council is strict, your architect needs to know that — it changes the design approach from "what can we get away with" to "what will definitely pass."
Most architects design based on planning policy and their professional judgement. Very few systematically check what's been approved and refused on the specific street where you live. That's not a criticism — it's a gap in the process. Filling that gap yourself, before you brief them, gives both of you better information to work with.
When You Should Hire an Architect First
There are situations where hiring an architect early makes sense — but they're fewer than most people think:
- You need feasibility help. If you're not sure what's physically possible on your site (structural constraints, access issues, drainage), an architect's initial assessment can clarify options before you commit to a direction.
- The project is complex. Multi-storey extensions, basement conversions, listed buildings — these need professional input from the start because the design and planning constraints are intertwined.
- You have strong precedent already. If you already know that four neighbours have the exact extension you want, there's less need to research further — brief the architect and reference the precedents.
For the vast majority of householder projects — a rear extension, a loft conversion, a side return — spending ten minutes checking nearby decisions before hiring an architect is the single most cost-effective thing you can do.
How to Brief an Architect Properly
Once you've done your research, here's how to turn it into a brief that gives your architect the best chance of producing drawings that get approved first time:
- Share the precedent. "Three houses on our street have single-storey rear extensions at 4m depth. One was refused at 6m. I'd like to stay within 4m." That's a brief your architect can work with immediately.
- Share the refusal reasons. "The refused application on our street cited loss of light to the neighbour's kitchen window. We need to be mindful of that." This tells your architect where the red lines are.
- Share the council's design guidance. If you've downloaded the relevant supplementary planning document, share it. Not every architect will have read the specific guidance for your council.
- Share the pre-application response. If you've had pre-application advice, that letter is the most valuable document in the entire process. It tells your architect exactly what the planning officer wants to see.
- Be realistic about scale. The most common cause of refusal is proposing something too ambitious for the site and street. If the data shows that modest extensions succeed and large ones fail, brief for modest.
Build your brief before you hire your architect
See what's actually been approved and refused near your postcode — the same decisions your planning officer will reference when assessing your application.
Check Your Postcode — Free →The Bottom Line
You need an architect for your planning application. But you don't need an architect to find out whether your idea is viable. That information is already sitting in the planning record — in the decisions that have been made on your street and in your council area.
Checking costs nothing. Not checking can cost £2,000–£5,000 in wasted drawings, plus months of delay if you need to redesign and resubmit. The smartest thing you can do before hiring an architect is spend ten minutes finding out what's already been approved and refused nearby. Everything else follows from that.
Ten minutes now can save thousands later
Check what gets approved on your street — before you commit to architect fees. 2,590,000+ real decisions across 240 UK councils.
Check Your Postcode — Free →