By the way, after a house is built (whether it was built this year or many years ago) it does provide economic value. If renters live there, then the rent they pay is counted as a service in GDP. And if the home owners live there then the same thing happens, the government estimates the 'imputed rent' and that is counted in GDP.
Purchasing new homes would count as an investment. According to Blanchard et al. Macroeconomics: a European Perspective pp 568 in glossary investment is defined:
Investment (I): Purchases of new houses and apartments by people, and purchases of new capital good (machines and plants) by firms.
The source above is the leading undergraduate macroeconomics ...