Client Blaming You for a Problem That Was Already There

‍‌​‌​‌‌‌‌​‌​‌​‌‌​‌‌‌‌‌‌​‌​‌​​‌​‍SiteKiln gives you plain-English information, not legal advice. It's aimed at small UK construction businesses. Laws change and every job is different, so speak to a solicitor or adviser before you rely on this for a real dispute.

When a client suddenly blames you for an old crack, damp patch or movement, the key question is cause, not volume of shouting.

1. The short version

In most construction disputes, it's the person making the allegation (usually the client) who has the burden of proof -- they need evidence that a defect exists and that your work caused it -- and the best way to knock shaky claims on the head is good before/after records and, where needed, an independent surveyor's report.

2. Where you stand legally (burden of proof)

• In UK civil cases (including building disputes), the burden of proof rests on the claimant -- the person alleging the loss.
• If a client says "your work caused X defect", it's on them to prove:
  • A defect exists.
  • It caused them loss.
  • It was caused by your breach of contract / negligence, not something else.
• To succeed, they generally need evidence of:
  • What the contract required.
  • Facts showing the work is defective or below standard.
  • A causal link between your work and the problem.
  • The cost of remedial works or other loss.
• You're not automatically liable just because a problem appeared after you were on site -- causation still has to be shown.
• There are some consumer law situations (especially with goods) where the burden can reverse in the first six months, but for building-work defects the general rule is still that the owner has to prove the defect and the link to your work.

So your job is to make it hard for anyone to credibly say "this was perfect before you came" when it plainly wasn't.

3. Work out what's genuinely new and what's old

When the finger gets pointed at you, slow things down and separate pre-existing from new.

Ask for specifics

• Exactly what they say you caused (crack, damp, movement, sticking doors, etc.).
• When they first noticed it.
• Any photos or reports they have.

Compare against what you already have

• Photos or videos from before you started and during the job.
• Any survey, homebuyer, or defects report the client shared before you priced.
• Messages where old issues were discussed (e.g. "this wall has always been damp").

Consider the building

• Is it older and already cracked/uneven?
• Are there obvious signs of historic movement, previous repairs, old damp?

Think about timing

• Did the problem appear mid-job when you did a specific thing (e.g. new opening, heavy plant on site)?
• Or has it crept in slowly over months/years?

This is the backbone of your "it was pre-existing / not caused by our works" story if you need one.

4. Use independent surveys when blame is serious

If they're blaming you for big-ticket issues -- structural movement, subsidence, serious damp, roof failure -- you're into expert-evidence territory.

Independent chartered surveyor / structural engineer reports

Courts and insurers rely on these for:

• Whether a defect exists and how serious it is.
• Whether it is new or historic.
• Likely causes (your works vs design vs pre-existing condition vs something else).
• Reasonable remedial options and costs.

If they get a report

• Ask to see it in full (not just cherry-picked quotes).
• Check whether the expert actually inspected before your works or only after.

If the blame is heavy and their report looks one-eyed

• Consider instructing your own expert to inspect and give a second opinion.

For insurance

• Your public liability insurer will almost always want an independent expert view before admitting or denying liability on a serious claim.

In bigger disputes, judges put a lot of weight on solid expert evidence and much less on shouting and finger-pointing.

5. Common mistakes

• Not taking "before" photos -- turning up to an old house and not recording existing cracks, sloping floors or damp is what lets people say "it was perfect before you came".
• Admitting blame too quickly in texts -- saying "yeah, that must be our fault, we'll sort it" before you've checked gives them a neat admission to wave later. Better to say "we'll inspect and see what's going on".
• Arguing technical cause without evidence -- saying "that crack is old" without photos, notes or, on big issues, a surveyor, won't carry much weight against a customer holding a report.
• Ignoring serious allegations -- if they're talking about structural damage, big damp problems or insurance claims and you just blank them, you risk being painted as reckless if this goes to insurers or court.
• Not looping in your insurer early enough -- sitting on a potential damage claim can breach your policy terms; insurers want early notice and a say in how experts and repairs are handled.

6. Who to contact

• Independent surveyor / structural engineer -- for serious cracks, movement, structural concerns or disputed damp/defects. Find via RICS: rics.org/find-a-surveyor (paid)
• Your public liability insurer / broker -- if there's any credible allegation of damage caused by your work, speak to them early and follow their process (included with policy)
• Solicitor with construction / professional negligence experience -- for larger jobs or where experts are already involved and blame is being thrown around (paid)
• Citizens Advice / Business Companion -- to understand what homeowners are told about defects and who has to prove what: businesscompanion.info (free)

7. Sources and legislation

• Burden of proof in civil claims -- general principle that the claimant must prove their case on the balance of probabilities. Applied consistently in construction defect cases.
• Consumer Rights Act 2015 -- sections 49-56 (services: reasonable care and skill, remedies). Note: the 6-month reversal of burden of proof under section 19 applies to goods, not services in the same way. legislation.gov.uk/ukpga/2015/15
• Limitation Act 1980 -- section 2 (6-year limitation for tort/negligence), section 5 (6-year limitation for breach of contract), section 14A (latent damage). legislation.gov.uk/ukpga/1980/58
• Defective Premises Act 1972 -- duty to build dwellings properly, with extended limitation periods under recent amendments. legislation.gov.uk/ukpga/1972/35
• Role of expert evidence -- CPR Part 35 governs expert evidence in civil proceedings. legislation.gov.uk/uksi/1998/3132/part/35

8. Related guides on this site

• 9.2 Customer claims defective work
• 9.4 Customer won't let you back to fix the work
• 9.7 Neighbour disputes from your client's work -- party walls
• 9.11 Customer demanding a refund -- when you have to and when you don't
• 8.5 Writing quotes that protect you
• 6.1 Public liability insurance

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