Looking on the internet deeply has found these results:

Twelve-floors is the most popular phrase on the web.

Twelve-floor 140,600 results on the web	Twelve-floors 1111,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Twelve for the lower floors, eight for the uppers. No terrace and I'm about... ...twelve floors down. No terrace and I'm about... ...twelve floors down.	No terrace and I'm about... ...twelve floors down. Twelve for the lower floors, eight for the uppers. No terrace and I'm about... ...twelve floors down.

Twelve-floor

140,600 results on the web

Twelve-floors

1111,000 results on the web

More popular!