What do I do if a builder walks off halfway through?

The instinct is to chase the builder and argue. That is the wrong first move, because the site is deteriorating, the evidence is decaying and the money question cannot be answered until somebody has established what was actually done. Doing the first three steps properly is what makes the fourth one winnable.

Safety

Step by step

1. Make the site safe first.Cover open excavations, isolate exposed electrical work at the consumer unit, make the building weathertight, and secure the perimeter. If scaffolding is up, contact the scaffolding company directly — inspection duties do not stop because the builder has gone.
2. Get a structural opinion if anything is open.Temporary propping, an unfinished opening, a beam not yet fully bearing. An engineer's visit before anyone works in that space is not optional.
3. Photograph and document everything before anything changes.Every room, every stage of work, every material on site. Date them. This is the record of what existed on the day they left, and it stops being obtainable the moment anyone else starts work.
4. Reconcile money paid against work done.List every payment with its date, and the milestone it was supposedly for. Set that against what physically exists. This produces the number the whole dispute is about.
5. Get an independent report.Another qualified builder or a surveyor, in writing: what has been done, to what standard, what remains, and what it will cost to complete and to correct. This is the evidence every later route depends on, and it must be obtained before remedial work starts.
6. Give them one written chance to return.A dated letter stating the position, the outstanding work, and a specific date by which they must return. Even where you have no expectation of a reply, every later stage asks whether you gave the opportunity.
7. End the contract properly rather than informally.If they do not return by the deadline, write again terminating on the ground that they have failed to proceed, stating the date and reserving your right to recover the cost of completing. Take advice on the wording on a large contract — terminating badly can put you in the wrong.
8. Deal with permissions and certificates.Contact building control with the application reference, explain that the contractor has left, and establish what inspections are outstanding. Chase any competent person scheme certificates, or their equivalent where you live in the UK, for work already done — these are much harder to obtain later.
9. Get the work finished.Expect a premium: builders are reluctant to take over another firm's unfinished work and will not warrant it. Get the new contractor's scope written to make clear what they are and are not taking responsibility for.
10. Then pursue the money.Letter before action with the independent report and the payment reconciliation attached, then the small claims track for modest amounts or advice on larger ones. If the trader was in a scheme, use its dispute route as well.
11. Check whether card protections apply.Where payments were made by card there may be separate routes with their own conditions and time limits. Those are covered by the Section 75 and chargeback guides, and they run in parallel with everything above.

Tips

• Do not let the new contractor start until the independent report is written. Once the unfinished work is covered up or corrected, the evidence of its state has gone.
• Keep tone measured in every written communication. Everything you write may be read later by a judge, an adjudicator or an insurer.
• If the builder has become uncontactable, check the register of companies before spending money on a claim — a dissolved company is a different problem requiring advice.

Common mistakes

• Getting the work finished before it has been recorded — The independent report and the photographs are the entire evidential basis for any claim. Once the remedial work is done there is nothing left to assess.
• Terminating verbally, or just stopping paying — An unclear termination can put you in breach instead of them. Write it, date it, state the ground, and take advice on anything substantial.

If it doesn't work

Questions people ask