Liability may rest with the builder under the contract, with designers and certifiers in negligence, and with a warranty provider under the policy terms. Which applies depends on the defect, the contract and how long ago the works were done.
Contractual claims against a builder are the most direct route but depend on the builder still trading. Where a company has been dissolved, the claim usually dies with it, which is why warranties and professional certification matter.
Claims in negligence against designers and certifiers require proof of a duty of care and a breach causing loss. Statutory limitation periods run from the date of the damage or its discovery, so delay is costly.