Basement bathrooms in Fort Collins
Adding a bath to the lower level, with the drain, backflow, fan and fixture rules Fort Collins inspects.
A basement bathroom in Fort Collins adds a toilet, a sink and usually a shower to the lower level, tied into the home's drain and vent system, protected against sewer backup and inspected by the city. It's for households adding a guest suite or a teen's room, and for anyone tired of the stairs. The goal is a bath that drains well, vents properly and holds up on a slab that may move.
What Fort Collins requires
- An approved backwater valve protecting new basement fixtures
- An exhaust fan ducted to the outside, or an operable window
- A dedicated 20-amp GFCI circuit for bathroom outlets
- Water-saving fixtures: toilets at 1.28 gallons per flush, showerheads at 1.8 gallons per minute and faucets at 1.5 gallons per minute
- An underground plumbing inspection when new drains go under the slab
- A 6 foot 4 inch minimum ceiling height in the shower area
Rough-in or new drains?
Many Northern Colorado homes built in recent decades have a capped rough-in for a future basement bath. If yours does, the work is mostly framing, finishing and fixtures. If not, the slab gets cut and trenched to reach the main drain, and the underground plumbing is inspected before the trench is filled. Where the drain is too high for gravity, an ejector pit handles it.
Plumbing on a floating slab
When a slab floats on expansive clay, drain lines that pass through it and walls that rest on it both need to allow for movement. Ask the contractor how they'll detail the shower base, the toilet flange and the wet-wall framing so a small rise in the slab doesn't crack tile or pull a joint.
What affects the cost?
- Existing rough-in versus slab cutting
- Distance to the main line and the backwater valve location
- Gravity drain versus an ejector system
- Half bath, three-quarter bath or full tile shower
- Fan, lighting, vanity and finish choices
Towns we cover
Common questions
Why does Fort Collins require a backwater valve for basement fixtures?
A backwater valve keeps sewage from backing up into the lowest drains in the house. The city's basement finish guide requires one to protect new basement fixtures.
Can a basement bathroom door open into the furnace room?
The city's guide says mechanical room access can't open into a bathroom or bedroom unless specific conditions are met, such as sealed-combustion appliances or an all-electric home.
Does the bath fan need to vent outside?
Yes. The guide calls for an exhaust fan ducted to the exterior, unless the bathroom has an operable window.
Related services
More background: Fort Collins basement finishing guide.
Planning a basement on Front Range clay?
Call and a local basement finishing company will look at the slab, the layout and the permit with you.