No, time is not an externality: maybe time under construction yields to disruption to neighbours under construction and we can charge for that. Resources are fully internalized. If a building needs x sand and another needs 2x sand, the second will pay twice for sand. Carbon is externalized, but that's a general problem. How do we know that making a lasting building is better/worse than having the building not exist / exist and having people driver farther / closer?
Simple, for externalities, you directly charge for the externality.
All these stop-gap "it costs carbon, so we must make it last 50 years" is like placing massive `if-then-else` statements throughout your codebase and then being surprised when the emergent behaviour of your program somehow results in uglier, more carbon polluting, sicker buildings that are now 100 years old and imposing massive costs on society around them.