It is common practice for developers or housing associations to request an exchange of contracts on new build properties before they are fully constructed. This is typically done to secure the sale, providing certainty for both the buyer and the developer.
For the developer, early exchanges can help fund the ongoing construction, while for buyers, it locks in the purchase price, protecting them from any future price increases.
You can request updates on the construction timeline and seek clarification on any delays before deciding whether to proceed. Additionally, your legal representation should ensure that the contract includes provisions that protect you in case of extended delays or significant issues with the build.