When remodeling wins
Remodeling keeps the foundation, structure, and shell, which are expensive to build from scratch. If the home is structurally sound and in a good location, remodeling almost always costs less and is faster than a full rebuild.
When building new wins
Building new can make sense when the existing home has major foundation or structural failure, when remodeling costs approach the cost of new construction, or when you want a completely different footprint that a remodel cannot deliver.