Installing a bathroom in a basement costs more than installing a bathroom above ground. Costs can range from $2,500 to $5,000 on average, depending on the number of fixtures and whether the plumbing must be installed from scratch or if it’s roughed in already. Basement plumbing requires special considerations to ensure proper drainage and tie-in with the main sewer line, which may not be deep enough to allow the basement bathroom plumbing to use gravity the way above-ground plumbing does. Virgil Miranda’s Construction subcontracts all plumbing work. Miranda says that sometimes the toilet alone in a basement can cost up to $2,500 because sometimes homeowners need to invest in a toilet that does not use gravity but instead a macerating function to grind waste down to prevent clogging. Miranda estimates that each bathroom fixture in a basement costs $800–$900 on average, so a full, three-piece bath could cost $3,000 for the fixtures alone. Adding a kitchenette or wet bar sink adds more to overall refinishing costs. In addition, some basements require a French drain with one or more sump pumps, which can cost up to $10,000 on average, depending on how much ground the drain covers.

A basement bedroom and full or half bath makes an ideal suite for guests or teens. Think about who will sleep in the basement and the amenities they'll need to help you determine the best dimensions for this basement remodeling idea. To comfortably fit a double bed, you'll need a room with a minimum of 125 square feet. If twin beds will serve your needs better, plan on at least 150 square feet. Building codes also require that basement bedrooms have an emergency exit that leads directly outside, either through a door or a window.
Accounting for variables such as square footage, materials, electrical and plumbing, the average basement remodel ranges from $11,034 and $29,226. Some cost as little as $5,000, with top of the line remodels costing over $40,000. The average cost to homeowners is $20,126. Expect to spend between $10 and $35 per square foot depending on the changes made.