How to Prepare for Building Work: The Pre-Start Review That Pays

This article is adapted from Chapter 5 of Your Seven Step Home Extension Plan by Ashton Paul — the book that shows homeowners how to manage a project and avoid the stresses and strains of the home extension process.

The most valuable week of your entire building project might be the one before anyone lifts a tool. Once the builders start, your leverage shrinks fast — before they start, you can still change almost anything for free. Here's how to use that week properly.

The pre-start review: your last free look

The pre-start review is one final opportunity to go over the design from head to toe and make sure you've covered every base. Speak to the subcontractors and get their insight before the works begin, rather than during them. Ask for suggestions — "is there a cheaper way to achieve this element?" is a perfectly good question, and Paul has no objection at all to this kind of re-engineering.

On large commercial projects, quantity surveyors are employed to do exactly this: recommending changes to the architect's design and selecting alternative materials specifically to save money. On a big job it isn't difficult to generate a 10% saving on the material specification alone — architects are well known for beautiful curved walls and top-end, well-known brands.

The timing matters enormously. There are no contractual cost implications for reducing the scope of works before the project starts — the builders are still competing to win the job and will play ball. Once you've started, your ability to get anyone to play ball is seriously reduced. So if the prices come back over budget, don't panic and don't push on regardless: get your three competitive quotes in, then run the review and trim the scope.

Put the risks on the table

This idea came from Paul's public-sector tendering days. After months pricing large maintenance contracts — typically £1 million a year — his team once applied £100,000 of priced risk to a contract. He won it, mobilised it... and the priced risks never materialised. He tried to give the money back, and couldn't find a mechanism in the contract to do it.

Builders do the same thing to homeowners, even when they're not conscious of it. There is always a perception of whether the client will be easy to work with and whether the project will be challenging — and that perception gets priced in as a quiet premium.

The pre-start review lets you put those risks on the table. Take the potential risks out of the cost of the works and into a contingency fund controlled by you. If the risk materialises, the funds deal with it. If it doesn't — well, as Paul puts it, that's your holiday sorted.

Say what "finished" looks like

Different people mean very different things by "decorated". Paul works with three distinct standards that any builder will understand:

• Builder's standard — one mist coat (watered-down emulsion), sand down, plus two further coats of emulsion
• Improved standard — one mist coat, sand down between each coat, plus two further coats
• Best standard — one mist coat, sand down between each coat, plus three further coats

Different preparation, different time, different cost. Ask yourself three questions: what standard would you be happy with, what standard can you afford — and, most importantly, what standard has your builder actually priced for?

A good set of terms and conditions setting out your expectations does something subtler too: it gives you permission to be yourself during the works. You won't have to second-guess what the builder is thinking or work up the courage for stern words — which, in Paul's experience, don't work very well anyway — because it's already there in black and white.

Lock the design down — changes cost at least 15% more

Paul once had a commercial client change their mind about an office partition layout on the Friday before a Monday start. The design had been completed and approved three months earlier; the materials were pre-ordered. He pleaded with them not to do it. That single change cost them £40,000 in materials, plus labour, VAT and professional fees.

Nobody expects you to know what a late change costs — so take it from someone who's counted: changes made after the start are usually at least 15% more expensive for the same works, plus any adaptive works around them. Occasionally you get away with it; usually you don't. And builders hate redoing work, so you'll strain the relationship with the trades at the same time.

The kitchen is the classic trap. You have a kitchen company in mind, so the designer doesn't design it, and six weeks into the build you pop down to the showroom — where they'd like to move a window and change a structural wall. During the design phase, your designer could have moved that wall on a computer screen for nothing. Mid-build, the structural recalculations and knock-on works can easily cost £1,000, and double that if you delay the decision. This is the "delayed design" problem we covered in how to plan a home extension — the pre-start review is your last chance to close it off.

One more reason to involve a fresh pair of eyes: on one of Paul's projects, reviewing the size of the rear bi-fold doors revealed that the kitchen's end unit sat too close — nobody had allowed space for the curtains to draw back. The kitchen designer made a small change before it ever became a problem. That's what a complete overview of the project buys you.

What it's actually like: dust, mess and the polythene sheet

Now for the honest bit about living through building work.

Your builder should always offer to erect temporary screening or a polythene sheet to keep dust and debris out of the parts of your home that aren't being worked on. Take the offer — but understand its limits. Fine dust gets everywhere regardless, and by morning it will have settled through more of the house than you thought possible. Realistically, set aside up to 30 minutes a day to keep on top of it. And try to resist taking a sneaky peek behind the sheet after the builders have left for the day.

Agree the tidying arrangements up front, because "builder's clean" is a genuine industry term for a reason — imagine how your son, brother or husband would leave a site they're returning to tomorrow morning. (The Friday clean-up is usually a bit better, as tools go home for the weekend.) On his own extension, Paul was quoted £400 per week for the builders to tidy up daily; knowing his wife would clean anyway — in half the time — he negotiated a discount instead and pushed the end of the working day back 45 minutes. That's the kind of trade you can only make if you've talked about it.

Valuables: remove them from the property, or keep them somewhere genuinely secure. In 28 years Paul has seen theft during works only twice — but when it happens, it's near-impossible to establish who was on site, and your insurer may not pay out if valuables weren't kept in an approved place. A lockable box in the loft is no good if the plumbers need loft access; and if you'll need jewellery for an event mid-build, make sure you can reach it.

Neighbours: skips, scaffolding lorries and a road full of vans test everyone's patience. During his own works Paul insisted the builder never parked across neighbours' garages — not even for five minutes — and apologised personally when a scaffold lorry delayed the school run. Agree with your builder before the start where vehicles can and can't go. Goodwill with the neighbours is cheap to keep and expensive to win back — we've written more about limiting disruption during an extension.

The pre-start checklist

From the end of Chapter 5:

• Review your budget and check affordability
• Re-engineer your solution where it saves money without compromise
• Remove any builder contingencies — hold your own instead
• Communicate your expectations, in writing
• Lock down the design
• Review the programme of works
• Check the procurement schedule for client-supplied items

Preparation is where projects are quietly won. It's also where our surveyor-led team does much of its work on every home extension we run — specification, pre-start review, terms and programme, before a single tool comes off the van. The complete process, with checklists for every stage, is in Your Seven Step Home Extension Plan (£12.99).