I saw a post online where someone (in the UK) is claiming they accidentally went to the wrong house to replace windows and the homeowner let them in, let them perform all the work, and then thanked them at the end but never informed them it was the wrong house.

I've seen dozens of reports about roofing and siding companies showing up and tearing off the roof/siding without ever talking to the homeowner and obviously they are liable but in the event the homeowner lets you in and lets you perform what is likely multiple days of work knowing it's the wrong house, wouldn't the homeowner be liable for payment?

An additional example: Another person commented on the post saying they replaced a front door for someone in Maryland (US) at the wrong address and a judge dismissed the case because "the homeowner might have thought it was a gift" and they couldn't prove otherwise. Seems likely another fabricated story but wouldn't it be pretty easy to prove no reasonable person would assume they are being gifted home renovations without at least being directly told it's a gift?

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    This also opens up a possibility of scamming. Hinting at (but not explicitly stating) the homeowner that it's free or has been paid and organized by a relative, but then demanding payment at the end. Or pretending it to be accidental, but in fact it was deliberate and then demanding payment. Sometimes with threat of violence if not paid. (I know of such cases of similar scams in my region)
    – vsz
    Commented Sep 4, 2023 at 7:32
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    Does it make a difference if the person who accepts the work is the homeowner or a tenant? Commented Sep 4, 2023 at 13:26

4 Answers 4


This is the classic fact pattern under which the contractor is entitled to an unjust enrichment remedy (and also often, a mechanic's lien remedy), even though there is no breach of contract claim.

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    Can you explain any of 'This is the classic fact pattern under which the contractor is entitled to an unjust enrichment remedy (and also often, a mechanic's lien remedy), even though there is no breach of contract claim.' What's '… the classic fact pattern…'? What's 'unjust enrichment'? What's a 'mechanic's lien'? How could 'breach of contract' come in? You turn up saying 'I've come to fix your (what)' I respond 'Are you sure? OK; go ahead' Then how am I liable for anything? Commented Sep 4, 2023 at 17:54
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    @RobbieGoodwin "Please explain how the householder is supposed to know that, in clear legal terms?" Unjust enrichment arises to pay for the fair market value of the work when the contract does work that an objective observer would understand was done with an expectation to be paid, and failed to tell to contractors to stop.
    – ohwilleke
    Commented Sep 4, 2023 at 21:38
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    @RobbieGoodwin "What's a 'mechanic's lien'?" A mechanic's lien is a right to collect the value of work on real property for which the contractors have not been paid by foreclosing on the property if it is not paid for by the owner, even if there is no contract between the contractors and the owner. "How could 'breach of contract' come in?" Normally, a contractor's obligation to be paid for work done arises from a contract between the contractor and the property owner. Unjust enrichment is an exception to that strong general rule
    – ohwilleke
    Commented Sep 4, 2023 at 22:26
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    Oh, thanks… and don't you think all that detail belongs in the Answer? Commented Sep 5, 2023 at 12:02
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    @ohwilleke I wouldn't say it's superflous details. Your answer is useful for someone with a background in law, but for others, it's kind of legalese. I for one did not understand what you meant, and had to refer to other answers - and based on the ups on Robbie's comment, at least 22 other people felt the same. I'm not saying it's a bad answer - it seems to be the most possibly conscise one that's still accurate - it's just... short.
    – Neinstein
    Commented Sep 6, 2023 at 7:49


If you're a contractor who screws up like this, chalk it up to experience and move along.

Unjust Enrichment

Here we run into some very choppy waters in Australian jurisprudence.

While the USA has already published its third restatement of the law of unjust enrichment, and the courts of England and Wales have handed down a five-stage test for it, and despite being, along with Canada, one of the pioneers in the field of this area of the law, unjust enrichment in Australia is a mess with State Supreme Courts disagreeing with each other about what the High Court has said about it. This is not entirely their fault, as the High Court has said different things at different times, including an abrupt about-face around the turn of the century and a cautious peeking back over the shoulder in recent years.

This article (Kit Barker, 'Unjust Enrichment in Australia: What Is(n’t) It? Implications for Legal Reasoning and Practice' (2020) 43(3) Melbourne University Law Review 903) gives a thorough analysis of the state of the law, and the author's summary slides consolidate it nicely (Kit Barker, 'Unjust Enrichment in Australia A Commentary', (PowerPoint Presentation) https://law.uq.edu.au/files/46387/Unjust-Enrichment-Commentary-Kit-Barker.pdf).

First, unjust enrichment in Australia is not a cause of action, in the same way that "tort" is not a cause of action; it is an umbrella term that captures a number of causes that have restitution as a remedy. Maybe - both the Victorian Supreme Court and the High Court have questioned the idea of this umbrella, but the HCA has also embraced it.

It is also not a discretionary, moral power given to judges to right an abstract "injustice" - the plaintiff must demonstrate a legal basis for their claim, evidence the facts that support it, and defeat any relevant defences.

For the fact patterns in the question, the only cause of action that I can see is the 'free acceptance' of a benefit. However, this basis is not an established part of Australian law; there is no settled case law on it. The best authority we have is Lampson (Australia) Pty Ltd v Fortescue Metals Group Ltd [No 3] [2014] WASC 162, but that was only a strike-out motion where the judge recognised this type of claim as "arguable" and allowed it to proceed, but the parties subsequently settled so we don't know who would win that argument. It is accepted that if the defendant had requested the benefit in some way, then restitution is open, but silence, in the absence of a duty to speak, is not a request.

If the contractors in your situations were to bravely embark on taming and defining the wilderness of Australian law on 'free acceptance,' they would need to show the defendant:

  1. knew the work was being done,
  2. knew or should have known that it was not being provided gratuitously and that the plaintiff expected to be paid for it,
  3. did not take a reasonable opportunity open to them to stop the work.

This would be heavily fact-dependent on what the defendant knew or should have known and when they knew it. There are obvious issues where, for example, a tenant knows about the work but the owner doesn't, or the property is part of a strata development, where doors and windows are owned by the body corporate, not the unit owner. Similarly, where the owner first knows about the work when irreversible damage has been done to the property, as in your cladding removal example.

Notwithstanding, if 'free acceptance' is a cause of action under Australian law and if it can be demonstrated to have occurred, the plaintiff still needs to demonstrate in broad:

  1. The defendant has been enriched. Windows or doors that replace perfectly functional windows or doors are unlikely to have materially enhanced the property's value, whereas a new bathroom or kitchen might have.
  2. That the enrichment happened at the plaintiff's expense. This one is pretty easy.
  3. That it was unjust, in the sense of being unconscionable, for the defendant to receive the benefit without compensating the plaintiff for it.
  4. That there are no defences, for example, that good consideration was provided, or that the defendant changed their position to its detriment due to the plaintiff's mistakes such that restitution would be unjust.
  5. It may also be necessary to determine if the remedy is personal or proprietary. That is, is the owner liable, or does the liability attach to the property?
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    – Dale M
    Commented Sep 6, 2023 at 22:20

In the UK, it is an implicit contract. Normally you have a written contract, or at least a verbal contract, but if that contractor just turns up at your doorstep by mistake instead of let's say your neighbours home, starts working, and you don't stop them, then you have an implicit contract and owe them money for the work.

This has actually happened when neighbour A called a landscaping company to landscape their garden while A went on holiday, the landscaping company went by mistake to neighbour B who didn't stop them, and did their garden. B had to pay. It would have been different if B had been on holiday as well.

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    @phoog Stopping someone from doing unauthorised work on your home/garden would be the normal response.
    – scotty3785
    Commented Sep 4, 2023 at 11:08
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    @phoog How about starting with "Who are you, and what are you doing in my garden?" That would seem like the normal response. When they say "Didn't you hire us for landscaping?" they'd say "no".
    – Barmar
    Commented Sep 4, 2023 at 12:02
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    @phoog 'I know nothing about this contract, so do not proceed.' would be a reasonable reaction. §241a - Unsolicited performance - German Civil Code: (2) Statutory claims are not excluded if the performance was not intended for the recipient or was made in the mistaken belief that there had been an order, and the recipient was aware of this or could have been aware of this had they exercised the care required in business dealings. Commented Sep 5, 2023 at 7:39
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    @Pyrotechnical I infer that, if the owner demonstrably had no opportunity to decline the work, they are not liable for payment. In other words, it is an absurd idea to build a business off of stealthily performing unsolicited, home improvements while the owners are away.
    – Corrodias
    Commented Sep 6, 2023 at 5:04
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    @akostadinov, the typical remedy is fair-market value; you end up with what a judge can be convinced a reasonable homeowner would expect that someone would normally pay for the service. Commented Sep 6, 2023 at 11:09

What you're describing would certainly be considered 'Unjust Enrichment' which is a form of civil fraud. The person who was enriched (e.g. the homeowner with the shiny new windows) is likely to be found liable for the amount of the benefit accrued at the expense incurred by the worker, including any harm suffered (e.g. if this resulted in a loss of business as a result). If the new windows have increased the value of the property by £5000, they would be liable for at least this amount.

...the claimant is entitled to seek a personal remedy that requires the defendant to pay the claimant the value of the enrichment which the defendant has obtained at the claimant’s expense (otherwise known as ‘restitution’). A claimant may also be able to seek remedies such as tracing into the defendant’s assets or claiming a declaration that the defendant holds an identifiable asset on trust for the claimant, or asserting a lien (right to possession) over an asset.

Ashford Law - Unjust Enrichment

If the claimant could prove that the homeowner acted to intentionally deceive the worker (for example, by telling them untruthfully that the work should be carried out on their property, not that of their neighbour), then this would rise to the level of criminal fraud.

A person [commits fraud if he [...] dishonestly makes a false representation [...] to make a gain for himself.

Fraud Act (2006)

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