What is a property chain and why do so many sales fall through?

A chain is a sequence of linked transactions where each one depends on another completing. You are buying from someone who is buying from someone else, and your own buyer is selling to fund their purchase. Everyone must exchange and complete on the same day.

The consequence is brutal arithmetic: the chain moves at the speed of its slowest link, and breaks at its weakest. A five-property chain requires five sets of solicitors, five mortgage offers, five surveys and five sets of nerves to align simultaneously. A single buyer at the far end whose lender withdraws collapses everything.

Roughly a quarter to a third of agreed sales fall through in England and Wales in a typical year. The usual causes:

Chain collapse elsewhere — often the largest single category, and entirely outside your control.

Mortgage problems — an offer withdrawn after a change in circumstances, or a down-valuation, where the lender's valuer values the property below the agreed price and the lender will only lend against the lower figure, leaving a gap the buyer must fund.

Survey findings prompting renegotiation or withdrawal.

Legal problems — missing building regulation certificates, title defects, lease issues, disputes with neighbours that must be disclosed.

Buyers or sellers changing their minds, which costs them nothing before exchange.

What reduces the risk: be chain-free if you can — cash buyers, first-time buyers and those who have sold and moved into rented accommodation are genuinely more attractive than a marginally higher offer. Ask the agent to map the whole chain before proceeding, and ask where each party is in their own process. Instruct a solicitor before you find a property. Keep in direct contact rather than relying entirely on agents.

A break in the chain is not always fatal — sometimes a replacement buyer can be found.