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From the code perspective: Basement finishing

Updated: 11/06/2017

Thinking about finishing your basement? Before you start, it's important to understand that unfinished basements are considered non-habitable space and valued as such in your home's valuation. When you decide to finish your basement or lower level, this space now becomes "habitable" and must meet certain building code requirements.

For example, habitable space requires electrical service for lighting and receptacle outlets. The spacing of outlets can be no greater than 12 feet and an outlet in stub walls greater than 2 feet in width. The number of outlets or lighting on a circuit is determined by the anticipated load on the circuit. 

Finished basements also require arc-fault, ground fault or possibly both types of circuits depending on their location. Tamper-proof outlets are also required.

When it comes to plumbing, you are not required to install plumbing in the lower level finish. However, if plumbing fixtures are to be installed, a plumbing permit is required. All work must adhere to state plumbing code. 

finished basement

If you're adding a sleeping room, an egress window and hardwired smoke alarm are required in the room. (Sleeping rooms are bedrooms or any other room that could be used for sleeping.) A hardwired smoke alarm is also required near the outside of the sleeping room, and a carbon monoxide detector within 10 feet of the room. The carbon monoxide detector can be hardwired, plug-in or battery type.

Building code does not require a closet in a sleeping room. A building permit is required for construction. If you do not get a building permit, the future sale of your home could be jeopardized.

Additional notes from building code:

  • Handrails are required on the stairs leading to the lower level.
  • No access to the mechanical room is permitted through bedrooms or bathrooms unless the door to the mechanical room is a solid, self-closing and gasketed door and the furnace is closed combustion and takes all air for combustion from the outside.
  • If the area under the stairs is framed to accept a door, the underside of the stairs and supporting framing needs half-inch gypsum applied.
  • A mechanical permit is only required when a fireplace is installed.

Lastly, please remember building permits are based on value, not the cost of the work. Check out our basement finishing handout [PDF] for more information.