Cost of Adding a Story in the Greater Montreal Area

  • Adding a story above a ground floor (+/- 1000 sq. ft.): costs begin at approximately $175,000, with an average of approximately $200,000
  • Adding a story (+/- 1000 sq. ft.) above a second floor to create a third floor, with basement: costs begin at approximately $210,000, with an average of approximately $250,000
  • Adding a story above a garage or another room (+/- 300 sq. ft.): costs begin at approximately $70,000, with an average of approximately $85,000. Note: In some cases, costs range from $100,000 to $125,000
  • Adding a half-floor above a ground floor (+/- 600 sq. ft.): costs begin at approximately $130,000, with an average of approximately $140,000
  • Adding a room (mezzanine style) above a flat roof (+/- 300 sq. ft.) with terrace on the roof: costs begin at approximately $125,000, with an average of approximately $140,000

Note

The budgetary amounts indicated here for adding a floor include all of the work for complete interior and exterior finishing, from the level of the ceiling of the ground floor or the floor that is below the addition. Below this level, the cost includes only a staircase connecting the two floors, if required.

Points to Consider That May Affect the Cost of Construction:

  • Level of complexity of the architectural integration
  • Modifications and strengthening of the existing structure, if necessary
  • Difficulty in attaching the new construction to the existing structure
  • Work to be done on the existing building in order to complete the work
  • Access to the worksite
  • Choice and number of doors and windows
  • Choice of materials