You design buildings for a living, working as an architect and designing everything from high-level skyscrapers to mansions to single-family homes. You do it all, and people pay well for your services.
Are the blueprints that you make considered intellectual property? Who owns them?
They are intellectual property, just like many other plans and creative works. You can think of blueprints much like an art form. The value inherent in those plans is that you created them and they are originals, which people literally cannot get anywhere else. The information on how to design the building is something that wouldn’t exist independent from you, even if the building has not been constructed yet. You have the right to protect those plans.
As far as who owns them, odds are that you do in almost every scenario. This question sometimes comes up when people are hired to do a job. If someone paid you to make the plans, do they have a claim to whatever you come up with? Generally, the answer is no. They may own the building, of course, but the two works — the physical building and the design of that building — are considered separate works.
This may also become important if you are hired initially to start a job and then get replaced with another architect. They cannot use the plans that you created as long as you hold the copyright for those plans.
People who work in creative fields understand the value of the works that they create and the ideas they develop. If those are in jeopardy or get used illegally, they must know what options they have.