Software development is not like building a house
Software engineering is a different beast, though. Fred Brooks wrote The Mythical Man Month in 1974, and it is often considered the "bible" of software engineering. In the book, he explains how creating software is different.
Brook's Law states that "Adding manpower to a late software project makes it later." It's important to keep teams small and agile, especially in the early stages when the architecture is in flux.
Creating usable, high-quality software takes a lot of time, skill and experience. Trying to cut a deadline by adding more people will almost guarantee the opposite effect.