Floor Framing

• Use span tables to select the joist size for the lumber species and grade, joist spacing, span and loads. Where in-floor heating requires concrete topping, floor joists should be deeper or more closely spaced.
  
• Consider how plumbing and ductwork will be installed without disrupting the floor system.
  
• Use floor sheathing and sub-flooring appropriate for the joist spacing and the type of floor finish.

Source : Canada Mortgage and Housing Corporation (CMHC)