Home Extension Top Tips: Paul's Ten Rules for a Successful Project

This article draws on Chapter 12 and the Top Ten Tips of Your Seven Step Home Extension Plan by Ashton Paul — and wraps up our chapter-by-chapter series on the book.

Over the past few months we've worked through Paul's book chapter by chapter — from who to phone first to what happens after the builders leave. This is the finale: the book's closing argument, and the ten tips Paul leaves every reader with.

First, the closing argument, in the form of four questions from Chapter 12. Would you agree that planning prevents poor performance? That your home extension is important enough to get right? Would a 15% budget overspend cause you a serious problem? Would defective work affect the value of your home? If you answered yes four times — and everyone does — then the case for running your project properly has already made itself. Paul ranks having building works done alongside moving house, getting married and having a baby on the stress scale, and his whole book exists because he believes those serious stresses are totally avoidable if you set the project up for success.

The triangle: cost, time, quality — pick one to protect

If you take a single idea from the entire series, take this one. Every project has three elements — cost, time and quality — and only two can ever be variables. Decide which one is most important to you, lock it down, and accept that the other two must flex.

Must be finished by a fixed date? Then be flexible on budget or on finish — not open chequebooks and shabby workmanship, just less than "best". Budget absolutely capped? Then be patient on time and pragmatic on finishes. Refuse to flex anything, and the project will choose for you — badly. And be honest with yourself: in Paul's experience, many "absolute" deadlines and budgets aren't real on inspection, and most of us are perfectly happy with standard finishes anyway.

Ask questions — it's what clever clients do

Some people fear that asking questions makes them look stupid. Chapter 12 argues it's the exact opposite: clever people ask lots of questions — they challenge the experts. If you don't understand the answer, that's the explainer's failing, not yours.

One of Paul's favourite-ever client openings: "Is it OK if I ask lots of questions, because I have never done this before?" The best question ever asked of him — she'd instantly validated her right to ask anything, and marked herself out as a smart information-gatherer who'd be a great client. (A builder who prefers clients that sit back and let him get on with it, unchallenged, is a builder the book suggests you don't work with.)

Two more people-skills from the chapter worth keeping. You won't gel with everyone on site — remember the three-strike rule: Paul once had a site manager removed from a project, a man good at his job whose habit of alarming the client with every problem, three warnings in, was making the project a nightmare. And when a tradesman's over-familiarity crosses your line, deal with it in the moment, briefly, and move on — the chapter even offers three go-to replies for the purpose: "I found that offensive", "Are you joking?" and a flat "What did you say?" Any of them beats weeks of silent irritation.

You already have the skills

Chapter 12's quiet confidence-builder is this: you've done all of this before, just not on a building site. Every job you've held ran on processes — some you followed, some you fast-tracked, and you learned from both. You already recognise a good boss from a poor one, which means you'll recognise a good, friendly tradesman from a not-so-good one. You know how you learn best — whether that's a full explanation, seeing it drawn, or (like Paul, a devoted repetition-learner) going over it twenty times — so tell your builder how you need things communicated, and let him meet you there.

The homeowners who struggle aren't the ones who've never built; they're the ones who assume their existing skills — organising, budgeting, managing people, handling friction — somehow don't count here. They count for almost everything.

Paul's Top Ten Tips

Here they are, exactly as the book closes — with our series notes attached.

1. Plan your project. The whole game. Unplanned projects routinely overspend by 25%, sometimes 100%. How to plan a home extension covers the realistic timeline and the plan that protects you.

2. Treat your project like a business. Your extension is a five-figure transaction in a £14bn industry — run it like one, and the return on investment follows.

3. Ask your builder for references. Every builder expects it; only the wrong ones resent it. How to find a good builder has the full vetting kit.

4. Follow up references — don't rely on online checking websites. Testimonials and directory reviews can be forged; fraudsters are smart. Speak to a former customer, or visit a completed project.

5. Don't rely on trust. Get to know the person you're getting into a relationship with. Almost every fraudulent builder appeared trustworthy at the start — that's how it works. Due diligence, not vibes.

6. Be a good client. Builders weigh you up like a credit rating, and good clients get the best prices. Clear the loft, provide the tea station, make decisions on time.

7. Don't pay money up front. The oldest trap there is. Staged payments in arrears, a 5% retention reducing to 2.5% through the defects period — the payment structure that protects you exists for a reason, and so does the snagging leverage it buys.

8. Have a written contract with your builder. Verbal agreements aren't worth the paper they're written on. What goes in the contract — dates, parties, contract sum, retentions — takes an afternoon to get right and saves thousands when it matters.

9. Manage your money. Know that only ~70% of your budget buys building work; hold your own contingency; get every variation written and priced within 14 days; check the final account. If problems do come, handle them early and in writing.

10. Don't postpone the design. Delayed design is the builder's profit margin and the client's regret. Lock it down at the pre-start review, then manage the builder against a programme instead of a guess.

Bonus tip, verbatim from the book: re-read the book, review the checklists, and make notes.

The seven steps, one last time

For anyone joining the series at the end, the process the book teaches — a homeowner-first simplification of the professional method Paul followed for two decades as a surveyor — runs: Step 0: Pre-start feasibility. 1: Design. 2: Approvals. 3: Specification of works. 4: Budget and estimating. 5: Contractual matters. 6: Building works. 7: Post-contract. Every post in this series slots into one of those steps, and every expensive mistake we've described comes from skipping one.

The method in action

If you'd like to see what surveyor-led project management looks like on real sites rather than in principle, we've written up several of our own projects — the brief, how the planning and build were run, and the numbers: a house converted into three flats on Hook Road, Surbiton, a single garage plot turned into a one-bedroom house on Mitcham Lane, and a 12-week house-to-HMO conversion on Pemdevon Road. Different projects, same seven steps.

Get the whole plan

A blog series can give you the shape of the method; the book gives you the working version — every chapter, every checklist, the template letters, the worked budget examples, and the case studies of real projects that went wrong and right. At £12.99 it is, without question, the cheapest thing you will buy for your extension — and the one most likely to save you a five-figure sum.

Order Your Seven Step Home Extension Plan here.

And if you'd rather have the authors of the plan run the project, that's precisely what our surveyor-led design and build service does — design, approvals, specification, contract, build and post-contract, one accountable team, exactly by the book.