When a builder constructs a home on their land without a specific buyer, this is referred to as:

The term used for when a builder constructs a home on their land without having a specific buyer lined up is "spec building." This practice involves the builder taking the risk of financing the construction of a home based solely on the belief that they will find a buyer once the home is completed. Spec homes are built with the intention of selling them after they are finished, appealing to potential buyers who may not want to wait for a custom home to be built to their specifications.

In contrast, custom building involves constructing homes based on specific requests from buyers, who typically provide input on the design and features. Commercial building pertains to properties intended for business use rather than residential purposes, while residential building is a broad category that encompasses all types of homes but does not specifically refer to the process of building without a pre-sold buyer in mind. Thus, spec building accurately describes the scenario presented.