Competing Agents: Why the Trade Who Understands Planning Wins the Job First

A kitchen fitter is on his knees measuring a 1930s semi in the rain, the homeowner hovering in the doorway with a mug of tea she's forgotten to drink. "We might extend the back at some point," she says. "Not sure though. Depends what we're allowed to do."

That sentence is the whole job, right there. Not the tape measure, not the cabinet run. Whether she signs with him next week or spends three more months collecting quotes from other trades depends almost entirely on what he says next.

Homeowners rarely hire the first person who turns up. They collect two, three, sometimes four quotes and let them compete: competing agents, all pitching for the same job, all trying to be the one she trusts by the time she's ready to commit. Most of them will talk kitchens. The one who talks about what the house can actually become, and why, is the one who gets the deposit before anyone else has finished their tea.

This guide is for that person. Builder, fitter, architect, developer: whoever in your trade ends up turning "we might extend" into a costed, drawn, buildable job.

The gap between "we might" and "we will"

Every homeowner who says "we might extend" is really asking one of five questions, whether they know it or not:

• What can I actually build on this house?
• Do I need planning permission, or can I just get on with it?
• We've just bought the place; what's realistic here?
• What have the neighbours had approved nearby?
• Will it add enough value to be worth doing?

Most trades answer the first one and stop. That's a mistake. The homeowner who's still turning the idea over in her head isn't blocked by design, she's blocked by uncertainty. She doesn't know what's permitted, what needs an application, what the council will knock back, or what it's actually worth doing. Answer all five and you're not quoting for a kitchen anymore. You're the person she calls when she's ready to build.

What the house could become, before you talk rules

Picture the same 1930s semi from a different angle: kitchen knocked into a side return, bifolds onto the garden, a vaulted ceiling with roof lights where the old flat-roof lean-to used to be. Or a 1970s link-detached with two extra bedrooms and an en suite tucked under a new upper storey that was never there before. Or a Victorian terrace with a full-width rear addition and a home office in what used to be a coal store.

None of that is fantasy. It's what permitted development rights, used properly, make possible without a full planning application. The trick is knowing exactly where the line sits, because the line is precise, and it's different for every house.

How far back can you actually go?

Under the rules that let most homeowners extend without full planning permission, a single-storey rear extension has to stay within set depth limits from the original rear wall, and it can't be higher than the existing house allows for. Go beyond that and you're not in permitted development territory anymore; you need an application. This is usually the first "yes, but" moment in any conversation with a client, and it's worth having ready rather than guessing on site.

Can you go up as well as back?

Since 2020 there's been a genuine upward route too. A house built between 1 July 1948 and 28 October 2018 can, in principle, gain extra storeys under permitted development: two more if it already has two or more storeys, one more if it's a single-storey house. There are real limits attached: the finished building can't exceed 18 metres in total height, each new storey can't add more than 3.5 metres, and if the house isn't detached, the new roofline can't sit more than 3.5 metres above the neighbour's. It never applies to listed buildings, and it doesn't apply on article 2(3) land at all (more on that below). Crucially, it's never automatic. It always needs prior approval from the council first, covering things like external appearance and how much daylight the neighbours lose. Tell a client "you can add a storey" without mentioning prior approval and you've set an expectation you can't deliver.

What actually stops a project dead

Two limits catch more homeowners out than anything else, and neither is obvious just by looking at the house.

The first is coverage. Everything non-original in the garden, existing extensions, existing sheds, the garage, the summerhouse, plus whatever you're proposing to add, can't push the total built footprint on that plot past 50% of the curtilage (the original house itself doesn't count towards that figure). A homeowner who's already got a garage, a garden office and a lean-to might be closer to that ceiling than they think, and a generous rear extension can tip them over it. This is worth checking before you draw anything, not after.

The second is location. If the house sits on article 2(3) land, meaning a conservation area, National Park, AONB, the Broads or a World Heritage Site, permitted development shrinks considerably. No side extensions. No two-storey additions to the rear. No cladding, render, timber, tiles or artificial stone on the outside without an application, whatever the house next door has already got. Plenty of homeowners in these areas assume the neighbour's extension proves what's allowed. It doesn't. It proves what was applied for and approved, which is a different question entirely, and one your client needs a proper answer to before they fall in love with a design.

The conditions that come with the permitted route

Even where permitted development does apply, it comes with conditions that catch out anyone rushing to get started. Materials need to look like the existing house, similar brick, similar roof tile, not necessarily identical, but close enough that it reads as one building (this doesn't apply to conservatories). Any upstairs side window has to be obscure-glazed and non-opening below 1.7 metres from the floor, which matters the moment you're planning ensuites or landings that face a neighbour. And where the new part rises more than one storey, the roof pitch has to match the original as closely as practical. None of this is a reason to avoid permitted development. It's a reason to design for it from the first sketch, so the survey doesn't come back with a problem nobody flagged.

The garden room that isn't as simple as it looks

A detached garden office, a summerhouse, a pool house: these fall under a different, more relaxed set of rules for incidental buildings, covering sheds, storage, garages, garden rooms, and things like oil or LPG tanks. The word doing the work there is incidental. The moment that garden room becomes a granny annexe with its own kitchen and bathroom, or a rented studio someone actually lives in, it's no longer incidental use and it needs planning permission like anything else. This comes up constantly with self-build clients wanting a "home office" that's quietly designed to be a bedroom later. Flag it early. It's cheaper for everyone than a retrospective application.

Do I need planning permission for an extension? How to answer without scaring anyone

Homeowners hear "planning permission" and picture months of delay, an angry neighbour, and a council letter that says no. Your job is to take the fear out of that sentence without pretending the rules don't exist.

The honest version goes like this: most single-storey rear extensions on an ordinary house, outside a conservation area, within the size and coverage limits, don't need a full application at all. That's genuinely good news, and it's worth saying plainly rather than burying it in caveats. Where it does need permission, that's not a disaster either; it's a process with a timescale you can plan the job around, and a well-drawn application on a straightforward house has every reason to succeed.

What loses trust is vagueness. "Should be fine, don't worry about it" is the sentence that gets a job cancelled six weeks in when someone mentions conservation areas at a dinner party. Precision is what makes you the trade people come back to.

Turning "we might" into a signed, costed job

This is the sequence that actually works, in order:

1. Find out what the house is allowed, not just what the client wants. Original build date, whether it sits on article 2(3) land, what's already in the garden that counts towards the 50% limit. Five minutes of research before the first meeting changes the whole conversation.
2. Show them the outcome first. A vaulted kitchen extension, a converted loft with a proper staircase, an extra storey with two new bedrooms. Give them the picture before the paragraph of rules that makes it real.
3. Name the constraint plainly. "You can do this without a full application, but here's exactly where the line sits" is a sentence that builds trust instantly, because it proves you actually know the answer rather than guessing.
4. Price against the realistic version, not the dream version they saw on a renovation programme. A costed drawing beats a verbal quote every time, especially when the figures match what's actually permitted.
5. Move fast while they're convinced. The homeowner who's just understood what her house can become is not in a mood to wait for three more quotes.

What the neighbours already had approved

Homeowners ask this constantly, and it's a fair question: what's realistic near me isn't an abstract national rule, it's what's already standing two doors down. You can't tell them what a specific neighbouring property was approved for unless you can point to something real and published, and guessing at precedent you can't actually show them does more harm than good if it turns out to be wrong. What you can do is be precise about the rules that apply to their own house and their own plot, and be honest when the honest answer is "let's check before we assume."

Does an extension actually add value?

A well-executed rear extension that adds a genuinely usable kitchen-diner, or a loft conversion that turns a two-bed into a three-bed, tends to move a house into a different bracket of buyer interest entirely, not just a slightly bigger number on the same bracket. That's the pitch worth making to a hesitant client: not "it'll cost X and you'll get Y back," because that number depends on the street, the finish and the market on the day, but "this isn't just more space, it's a different kind of house." That reframing, more than any spreadsheet, is often what gets someone off the fence.

How this makes you the trade who wins the quote

Every homeowner comparing you against other trades is running competing agents for the same job, whether they'd use that phrase or not. Two or three people, all pitching, all polite, all saying roughly the same things about quality and timescale. The one who arrives already knowing what the house is permitted to become, without needing to check and call back, is the one who looks like they've already done the job in their head. That's not a sales trick. It's just being ready before the meeting instead of during it.

If you want that readiness built into how you work day to day, /for-trades has the local page built for exactly this: research on a specific property before you walk in, so you're never guessing on the doorstep. And if you want your business to be the name a homeowner sees the moment they check what their own house could become, /product-placement is the featured seat that puts you there at the point they're deciding, not after they've already picked someone else.

Worth seeing in practice: the Rear Extension Experience shows exactly this in action, running a real property through what's permitted, what needs an application, and what the finished result could look like, the same walkthrough you'd want ready before your next quote.

What this house could become

Strip away the jargon and every one of these conversations is really about the same thing: a family standing in a house that's slightly too small for them, wondering if it could become the house they actually want to live in. Most of the time, it can. The kitchen that opens onto the garden, the loft that becomes two proper bedrooms, the whole extra storey that was never part of the original plan: it's all sitting there in the rules, waiting for someone who can read them properly.

Be that person before the other quotes land. Put the address in, see what the house could become, and walk into that first meeting already knowing the answer.