Stage 5: During the build

Three habits protect your money once the work starts. Pay for what exists. Price every change before it happens. Write down what happened, the day it happened.

None of them take long. All three fail in the same way, which is that they get abandoned in week four when the build is going well and nothing seems to need them.

5.1 Paying for what exists

The single rule that protects a self-builder’s money: pay for what has been built, not for what has been promised.

It sounds obvious and it is broken constantly, because the mechanism by which it gets broken is entirely reasonable-looking. The builder sends an application for payment. It has a number on it. The number is roughly what you expected. You pay it.

The problem is that the application is the builder’s assessment of their own work, prepared by somebody who benefits from it being generous, and it is almost always prepared optimistically rather than dishonestly. The roof is “about 80 per cent” when it is about 45 per cent, because they have been on it all week and it feels close.

What paying ahead of value actually costs you is not the money, which you would have paid anyway. It is your position. If the builder stops, walks, or fails, the money you have paid over the value of what is standing is money you will not see again. Every month you pay ahead, you are lending your builder money unsecured.

The method, once a month, and it takes about an hour.

1. Walk the site with your cost plan. Package by package, decide what proportion is genuinely complete. Not what has been started. What is finished.
2. Take a photograph of anything you are unsure about, with the date.
3. Work out the value. Each package’s contract value multiplied by its percentage complete, added up.
4. Add agreed variations, at their agreed prices, to the extent the work is done.
5. Take off retention, which is the small percentage your contract lets you hold back.
6. Take off what you have already certified.
7. What is left is what is due.
8. Only now, read the builder’s application. Not before, because you cannot unsee their number once you have seen it.
9. Record the difference and tell them the same day, in writing, with your reasoning.

On retention. It is usually five per cent, held from each payment, with half released at practical completion and half at the end of the defects period. It exists so that at the end of the job there is money in your hands rather than theirs, which is the only practical reason a builder ever comes back to fix something. Many domestic contracts do not provide for retention at all. If yours does not, you have nothing held back at the end, and you should know that when you sign rather than when you are chasing a snag list.

The Aldertons, valuation 4, end of June

Stage 5 valuation assessment

Description	Amount
Gross value of work done, their own assessment	£164,300
Less retention at 5 per cent	(£8,215)
Less previously certified	(£118,900)
Due this valuation	£37,185
Kestrel’s application	£46,000
Difference	£8,815

The difference was the roof covering, applied for at 80 per cent and actually at about 45. Tom sent three lines that afternoon: here is our assessment, here is a photograph of the roof taken this morning, the balance follows next month.

Kestrel agreed by return. It took four minutes, and it happened four times across the build.

That is the whole job. Not catching a cheat. Just paying for what exists.

The tool: the Payment and Valuation Tracker.

If your build is run differently

On trades direct, you do this per trade rather than once, and the discipline matters more, because each trade is asking you directly and there is no main contractor absorbing the optimism.

If your build is run differently

Where an architect or project manager certifies for you, they do this assessment and you should still read it. Ask what they walked and what they measured. A certificate is a professional’s judgement, not a rubber stamp, and it is your money.

5.2 Changes, and the four minutes that pay for themselves

Every self-build changes as it is built. What ruins budgets is not the changes, it is agreeing them without a price.

The mechanism is always the same. Somebody is on site. A question comes up. It gets answered in conversation. Work happens. Weeks later a figure appears, and it is bigger than you imagined, and there is nothing to discuss because the work is already done.

The gate is simple: no change starts until its price is agreed in writing.

That is it. One rule, and it holds because of the order it puts things in. Before the work, you have a choice: accept the price, negotiate it, or decide not to do it. After the work, you have no choice at all. Your entire negotiating position is the fact that the work has not happened yet, and it evaporates the moment somebody picks up a spade.

How to run it.

When a change comes up, send a form. What you want changed, why, and whether it is urgent. Say so honestly if it is: urgency costs money and you should know that it does.

Ask for a price and a programme effect, and say plainly that the work is not instructed until you have confirmed the price in writing.

When the price comes back, decide. Accept, negotiate, or drop it. If you accept, say so in writing.

Then put it in the register, with its number, its description, its dates and its price.

Register everything, including the ones you got wrong. A change agreed on site without a price still goes in the register, marked as agreed after the work. Those entries are the ones that teach you, and they are also the ones that stop the final account being a surprise.

Why the register matters more than it looks. It is not admin. It is the document that makes your final account take an afternoon instead of a fortnight, because at the end of the job the final account is simply your contract sum plus everything in this register. If the register has been kept, there is nothing to reconstruct and nothing to argue about.

The Aldertons, at valuation 4

No.	What changed	Amount	Priced first?
1	Upgrade windows to triple glazing	£3,800	Yes
2	Move the utility room door	£550	Yes
3	Additional drainage run to the garage	£2,100	No

Number 3 is the lesson. It was agreed on site on a Tuesday, in a two-minute conversation, and the groundworker was digging it the next morning. The price came afterwards: £2,100 against the £1,400 the Aldertons had assumed.

There was nothing to argue with, because the trench was already in the ground.

It is the only one of the three that still annoys them. The £3,800 window upgrade was four times the size and it does not annoy them at all, because they chose it knowing what it cost.

The tool: the Variation Register and Instruction Form.

5.3 The record that settles arguments

Five minutes a day, and it settles every argument that follows.

A record written as the work runs is a record. The same facts reconstructed eight months later are a story, and everybody knows the difference, including you.

It costs nothing while the build is going well, which is precisely why it is worth keeping then. Nobody starts a diary on the day it goes wrong; by then the six weeks you needed are gone.

Three things, daily.

The diary. One row. Who was on site, what got done, the weather if it stopped anything, what was delivered, and anything said that matters.

The photographs. Three a day is plenty. Take them from the same places so they compare. Get them off your phone into a dated folder the same day, because a photograph nobody can find is not evidence, and the day you need it is never a day you have time to look.

The written confirmation. Where something was agreed verbally and it matters, send an email the same day. “Just to confirm what we agreed this morning: you will…” That email is worth more than the diary entry, and the diary entry is what reminds you to send it.

The Aldertons, four days in June

Date	Who	What got done	Anything said
12 Jun	Kestrel, 4 + roofer	Roof battens, felt to rear slope
13 Jun	Kestrel, 2	Rain. Internal blockwork	Roofer says two days lost to weather
16 Jun	Kestrel, 5	Roof tiling front slope	Site manager asked about an extra drainage run to the garage. Said we would price it first
17 Jun	Kestrel, 5 + groundworker	Drainage run to garage dug	Work started before we had a price. Our own fault: we did not send the form

Ninety seconds a day. Those four lines are why variation 3 cost £2,100 rather than £1,400, and also why nobody argued about it, because the diary said plainly what had happened including the part that was the Aldertons’ own mistake.

A record that only ever records the other side’s failings is not a record. It is an argument, and it reads like one.

The tool: the Site Diary and Photo Log.

5.4 When it goes wrong

Three situations, and what to do in the first week of each.

The builder is asking for money you do not think is due. Do not pay it and do not ignore it. Send your own assessment with your reasoning and your photographs, the same day, and say what you are certifying and why. Most of these end there. If it hardens, stop and get advice before you write anything else, because what you write in week one gets read out in month six.

The work is not good enough. Write it down, photograph it, and raise it in writing immediately rather than waiting for the snag list. A defect raised at the time is a defect; the same defect raised at the end, after you have paid for the work, is a negotiation. Be specific about what is wrong rather than that you are unhappy.

The builder has stopped, walked, or failed. This is the one where the first week decides everything.

1. Secure the site. It is your site and your materials. Change the locks if you need to.
2. Photograph everything, immediately, before weather and strangers get to it. This is the single most important thing you will do, and the window for it is days.
3. Value what is standing, package by package, as at the day they stopped. Your payment tracker gives you most of this already.
4. Work out where you stand. What you have paid, what is actually built, and the difference. If you have been paying for what exists, that difference is small. If you have not, this is when you find out.
5. Find out what has been paid for and not delivered, and where those goods are.
6. Do not sign anything, and do not accept an offer to complete the work, until you know the position.
7. Get advice. If it is insolvency, there is an insolvency practitioner involved and a process with rules. If it is a walk-out, it is a contract question. Either way it is not a thing to work out from a forum post.

And the thing nobody tells you: re-procuring the remaining work is its own tender, and the enquiry pack from Stage 3 is exactly the tool for it. You will need a clear scope of what is left, and you now have a half-built house that nobody else priced.