How to write a builder quote that protects your margin.

Why builders lose money on the paperwork.

Ask a builder where a job went wrong and you rarely hear "I priced it too low". You hear that the customer changed their mind, that something unexpected came out of the ground, or that nobody agreed what "finished" meant.

All three are paperwork problems. Commercial contractors solved them decades ago with phased scopes, provisional sums and variation clauses. There is no reason a domestic extension should be quoted with less structure than a commercial fit-out.

A proper quote does not just win the job. It decides whether the job makes money.

Phased scope of works.

Break the job into phases the customer can follow and you can invoice against. For a typical extension that might be:

1. Site set-up, protection and enabling works
2. Groundworks and foundations
3. Structure: walls, steels, roof
4. Weathertight: windows, doors, roofing complete
5. First fix: electrical, plumbing, carpentry
6. Plastering and second fix
7. Finishes, snagging and handover

Phasing does three things at once. It makes the price feel reasoned rather than plucked from the air, it gives you natural stage payments, and it gives you a clean place to record a variation when the customer changes something.

Provisional sums and prime cost items.

You cannot price what has not been chosen. If the customer has not picked the kitchen, the tiles or the bathroom suite, do not guess and absorb the difference.

Use a provisional sum for work that is not fully defined, and a prime cost sum for supplied items the customer will choose later. State clearly that the sum is an allowance, that the final cost will be adjusted to the actual, and that the difference will be added to or deducted from the final account.

One line prevents the most common argument in domestic building: "but I thought that was included".

The variation clause that saves the job.

The customer will change something. That is not a problem, it is normal. The problem is doing the extra work first and discussing the money afterwards, when you have no leverage and they have already had the benefit.

Your quote should say, in plain words, that any change to the scope will be priced and agreed in writing before it is carried out, and that agreed variations are added to the final account. Then actually do it. A short written note or email per variation is enough.

Staged payments and cash flow.

A builder funding a customer's extension out of their own account is a builder one slow payer away from serious trouble.

Tie payments to the phases you have already set out. A deposit for materials and set-up, then payments at agreed milestones such as foundations complete, weathertight, and plastering complete, then a final balance on completion.

Say when each payment is due, in days, and what happens if it is late. On larger domestic jobs it is reasonable to state that work pauses if a stage payment is overdue.

Building Regulations and who is responsible.

Be explicit about who is applying for and paying for building control, whether that is a local authority or an approved inspector, and who is responsible for any planning permission.

State what happens if the building control officer requires additional work. If that is outside your quoted scope, say so, and price it as a variation when it arises.

Retention and snagging.

If the customer wants to hold a retention, agree the percentage, what triggers its release and by when. Open-ended retention is how final payments disappear.

Define "complete" too. A short snagging clause saying that minor defects will be remedied within an agreed period, and that this does not delay the final payment beyond the agreed date, keeps the end of the job clean.

Common mistakes that cost builders money.

• One lump sum with no breakdown. Impossible to defend, easy to haggle.
• No provisional sums. You end up paying for the kitchen they upgraded.
• Verbal variations. The work gets done, the money does not.
• No stage payments. You become the customer's bank.
• No definition of complete. The final payment drifts for months.

Copy-paste builder quote template.

What to do next.

Take the phase structure above and apply it to the next job you price. Add provisional sums for anything not yet chosen, and put the variation clause in writing.

Then follow the quote up at day 2, day 5 and day 10. On bigger jobs the customer is often getting three prices and waiting to see who seems most organised. Following up properly is part of that impression.