Basement Planning
Updated September 2026
Most Johnson County basement finishes need a permit, ceiling height and egress are the two code questions that shape the plan, and BBD basements have run $80,000 to $550,000 and 9 to 16 weeks of construction. Start here.
11 min read
Written by Mike Schwartz, Built by Design | Published May 4, 2026
Finishing a basement in Johnson County is usually the least expensive way to add living space, because the foundation, walls, and roof already exist. It's also where plans go wrong quietly: a ceiling that's four inches too low for a bedroom, a window well that doesn't count as egress, a bar drain that has to pump uphill, or a furnace boxed in behind a new wall.
This guide walks the decisions in the order they come up on a real project, with the code numbers cities in the county adopt, the permit path for each city, and what Built by Design's fourteen published basements in Overland Park, Olathe, Lenexa, Leawood, Shawnee, and Parkville cost and took to build.
For the cost side of the same decision, read what a finished basement costs in Kansas City. For the service itself, see basement remodeling with Built by Design.
Every BBD basement started as a list of uses, not a floor plan. The list matters because each use pulls the plan in a different direction: a theater wants a wall without windows and a door that closes; a bar wants a drain, a dedicated circuit, and a route to the stair; a gym wants ceiling height, a rubber floor, and separation from the lounge; a guest suite needs an egress window and a full bath; an office needs daylight and quiet. Write the uses in order of how often they'll happen. A room used every weekday (an office, a gym) should get the daylight and the best headroom. A room used on Saturday nights (a theater) can take the interior corner with no windows. Fourteen documented BBD basements show the pattern: the theater almost always sits against a windowless wall, the bar sits near the stair, and the gym gets glass doors so it borrows light without sharing noise.
| Use | What it needs from the plan | Documented BBD example |
|---|---|---|
| Theater or media lounge | A windowless wall, light control, a door or a way to contain sound, sconces or dimmable lighting | Overland Park theater with recliners and a popcorn station |
| Wet bar or basement kitchen | A drain (or an ejector pump), a dedicated circuit for refrigeration, counter depth for real inventory, a route from the stair | Overland Park full basement kitchen with a wood island |
| Gym | The tallest headroom, rubber flooring, separation from the lounge, ventilation | Overland Park glass-door gym beside the theater |
| Guest suite | An egress window or door, a full bath, a door that closes, a closet | Olathe basement with a finished bedroom and powder bath |
| Office | Daylight, quiet, outlets and data where the desk goes | Shawnee office with a slat accent wall |
The International Residential Code, which Johnson County cities adopt with local amendments, sets habitable rooms at a minimum 7-foot ceiling. In basements it allows beams, girders, ducts, and similar obstructions to come down to 6 feet 4 inches above the finished floor, and portions of a basement that are not habitable (hallways, storage, mechanical) can be 6 feet 8 inches. Those three numbers decide more basement layouts than any finish selection. Measure from the slab, not from the joists, and measure under the main trunk duct, the beam, and any plumbing drop. Then subtract the finished floor and the finished ceiling. A basement that reads as 7 feet 6 inches at the joists can end up at 6 feet 10 inches under a duct after flooring and drywall. That's fine for a hallway and not fine for a theater seat. The usual fixes, from cheapest to most involved: put the low areas to work as hallways and storage; run soffits along walls instead of across rooms; reroute a duct or a drain line while the ceiling is open; and only as a last resort, lower the slab, which is a structural and waterproofing project in its own right. Confirm the exact requirement with your city, because each adopts a specific code edition and amends it.
See also: ICC: International Residential Code, Chapter 3, Building Planning
No finish survives a wet basement. Before design starts, get an honest history: any water at the walls or the floor, when it happened, what the grading and gutters look like outside, and whether a sump exists and works. Walk the exterior after a hard rain if you can. A basement that took water once in a decade can be finished; the plan just has to respect the cause. Below grade, comfort is about the wall assembly and the air, not the thermostat. Insulation against the foundation wall, a vapor strategy that matches the wall type, a dehumidifier or conditioned air that actually reaches the space, and flooring that tolerates concrete's moisture are the decisions that make a basement feel like the rest of the house. Light wood-look plank flooring shows up in most BBD basements for that reason: it's warm underfoot, it handles slab moisture better than solid hardwood, and it keeps a lower level bright.
If anyone will sleep in the basement, the room needs an emergency escape and rescue opening: a window or door to the outside that a person can climb through and a firefighter can climb in. The code also requires one for the basement as a whole once it has habitable space. The numbers below are the IRC's, and Johnson County cities adopt them with local amendments, so confirm the edition and any changes with your building department. The practical consequences: a window well is almost always part of the project, its size and any ladder are part of the permit drawing, and the excavation, the well, and the window are a real line item. A closet and a door don't make a bedroom; the egress does. That's also why BBD's basement guest rooms are planned with the window first and the furniture second.
See also: ICC: IRC Section R310, Emergency Escape and Rescue Openings
The stair is the front door of the basement. Where it lands decides what people see first, how furniture gets down, and how far a guest walks to the bathroom. Most existing stairs stay where they are; the plan works around the landing. If the stair is open to the main floor, plan for sound: a theater or a game room at the bottom of an open stair is a theater for the whole house. Sound separation is cheap while the ceiling is open and expensive afterward. Insulation in the joist bays, solid-core doors on the rooms that make noise, and a door (or sliding barn doors, as in BBD's Shawnee basement) between the game room and the lounge do most of the work. The IRC stair numbers below apply if the stair is rebuilt or a new one is added.
Water in a basement flows to a drain that sits below the floor. Where the main sewer line leaves the house decides whether a new bathroom or bar can drain by gravity or needs an ejector pump. Find that line before you place the bathroom, because moving the bathroom ten feet can be the difference between cutting a trench and adding a pump, a pit, and an alarm. BBD's documented basements include full bathrooms in most of them, wet bars in nearly all, and true basement kitchens in two. The bar decisions that matter: a sink and drain or a dry bar, refrigeration on its own circuit, a dishwasher if the bar will host, and enough counter and back-bar depth to hold real inventory. A bathroom below grade also needs an exhaust fan that vents outside, not into the joists. The IRC requires 50 cubic feet per minute intermittent or 20 continuous for a bathroom exhaust (IRC M1505.4).
| Decision | Gravity drain available | Ejector pump needed |
|---|---|---|
| Where the bathroom goes | Near the existing sewer exit, trench in the slab | Anywhere, but budget the pit, pump, vent, and alarm |
| Wet bar sink | Trench to the main line | Small sink pump or route to the ejector |
| Basement kitchen with dishwasher | Same trench, larger drain | Pump sized for the added flow |
| Laundry relocation | Trench plus a standpipe | Pump plus the washer discharge rate |
The furnace, water heater, sump, electrical panel, main shutoffs, and any cleanouts stay reachable after the walls go up. Shawnee's basement permit handout asks applicants to draw the unchanged mechanical areas for exactly this reason. Plan a mechanical room with a real door and enough floor space to replace the equipment, and keep the panel clear in front. Lighting does most of the work of making a basement feel like a main floor. Recessed lighting on separate switches for the lounge, the bar, and the hallways; pendants over any island; sconces at the theater wall; and dimmers on everything that faces a screen. Decide on a drywall ceiling versus a drop ceiling by what's above it: if a lot of plumbing and valves live in the joists, an access panel plan or a drop ceiling in the mechanical zone saves a future repair from becoming a drywall project.
Nearly every basement finish that adds walls, wiring, plumbing, or a bedroom needs a building permit, and the drawings and inspections differ by city. The six cities BBD works in most publish their own guidance; the links below were checked on September 28, 2026. Confirm the current requirements for your address before scheduling work that depends on a permit. Parkville is in Missouri and has a separate path from the Kansas cities.
| City | Department | The question to settle for your address |
|---|---|---|
| Overland Park, KS | Building and Construction | Which permit guidance and inspections apply to this address and proposed scope? |
| Leawood, KS | Code Services and Building Permits | Which drawings and reviews should accompany an interior remodel or addition application? |
| Lenexa, KS | Remodeling Projects (residential construction) | Which plan details, contractor registrations, and inspections does this remodel need? Lenexa also publishes basement-finishing and emergency-escape guides. |
| Olathe, KS | Building Permit Application Guide | Which residential application fits the project, and are sealed plans required? |
| Shawnee, KS | Community Development and Building Permits | Which basement-finish guidelines and inspections apply? Shawnee asks for remodeled and unchanged areas on the plan. |
| Parkville, MO | Development Permits | Is the property inside city limits, and which reviews apply? |
See also: Remodeling permits in Johnson County: what needs one and where to apply
Built by Design's previously published basement project range is $80,000 to $550,000. Where a project lands depends on square footage, whether it includes a bathroom, a bar or a kitchen, built-ins, a theater build-out, and how custom the finishes get. The cost page breaks that range down by scope. Construction time is recorded in the case studies. The basements with a recorded timeline ran 9 to 16 weeks on site: 9 weeks for an Overland Park basement with two serving zones and a theater wall, 11 weeks for a Lenexa basement built around a vintage collection, 13 weeks for the Parkville open lower level and for the Leawood basement that also updated the upstairs kitchen, 14 weeks for Shawnee and for the Overland Park theater with a glass gym, and 16 weeks for the Overland Park basement with a walk-in wine cellar. Those weeks are construction only; design, permitting, and product lead times come first.
| Project | What it included | Recorded construction |
|---|---|---|
| Overland Park, two serving zones | Kitchen-style wet bar, beverage station, theater wall, bathroom | 9 weeks |
| Lenexa, vintage collection | Wet bar with island, movie lounge, fireplace, pool table area | 11 weeks |
| Olathe, glass gym | Glass-door gym, theater wall, pool table, wet bar, powder bath, bedroom | 11 weeks |
| Olathe, projector theater | Projector theater, pool table, wet bar, gym, bathroom, plus an upstairs guest suite | 12 weeks |
| Parkville, open lower level | Theater, gaming area, built-in theater bar, back wet bar, dining nook | 13 weeks |
| Leawood, basement and kitchen | Custom wet bar, fireplace lounge, game area, plus an upstairs kitchen update | 13 weeks |
| Shawnee | Theater lounge, wet bar, bathroom, game room behind barn doors, office | 14 weeks |
| Overland Park, family weekend space | Theater wall, wet bar, drink cellar, glass-door gym, kids area, bathroom | 14 weeks |
| Overland Park, wine cellar | Walk-in wine cellar, wet bar, theater lounge, pool and arcade, glass gym, office, bathroom | 16 weeks |
See also: What a finished basement costs in Kansas City, by scope
Mike and Kristen meet homeowners at the home. For a basement, the first visit is a walk of the lower level with a tape measure and a flashlight: headroom under the ducts, the sewer exit, the panel, the sump, the windows, and any sign of water. Bring the list of uses, any drawings the house came with, and a realistic window for when construction could start, allowing for design and permitting first.
See also: Request an in-home consultation
Built by Design meets homeowners at the home, writes one scope before finishes are chosen, and builds with the same trade partners named in the case studies above.
FAQAnswers, by design
The basement questions Johnson County homeowners ask most, answered with the code numbers cities adopt and what BBD has built. Your city and your project team confirm what applies to your house.
Almost always, yes. Adding walls, outlets, lighting circuits, plumbing, a bathroom, or a bedroom triggers a building permit and inspections in Overland Park, Leawood, Lenexa, Olathe, and Shawnee, and in Parkville on the Missouri side. Paint and flooring alone usually do not. Each city publishes its own guidance, linked above, and confirms the requirements for a specific address.
The International Residential Code sets 7 feet for habitable rooms, allows beams and ducts in basements to come down to 6 feet 4 inches, and allows 6 feet 8 inches in non-habitable areas like hallways and mechanical rooms. Measure under the lowest obstruction and subtract the finished floor and ceiling. Your city adopts a specific edition with amendments, so confirm the number that applies.
A net clear opening of at least 5.7 square feet (5.0 at grade), at least 24 inches high and 20 inches wide, with a sill no more than 44 inches above the floor, opening to the outside. Below grade it needs a window well of at least 9 square feet projecting 36 inches from the wall, with a ladder if the well is deeper than 44 inches. A basement bedroom needs one, and the basement as a whole needs one once it has habitable space.
BBD's basements with a recorded construction timeline ran 9 to 16 weeks on site: the shortest was an Overland Park basement with two serving zones and the longest was an Overland Park basement with a walk-in wine cellar, glass gym, and theater. Design, permitting, and product lead times come before those weeks and vary by project.
Built by Design's previously published basement range is $80,000 to $550,000. Square footage, a bathroom, a bar or kitchen, a theater build-out, built-ins, and finish level move a project within that range. The basement cost page on this site breaks the range down by scope.
You can, but the cost depends on where the sewer line leaves the house. A bathroom near that exit can drain by gravity through a trench in the slab. A bathroom far from it needs an ejector pump, a pit, a vent, and an alarm. Find the line before you place the bathroom.
It's usually the least expensive square footage you can add, because the structure already exists, and a basement the family uses every week is worth more to daily life than resale math suggests. For resale, ask a local agent about comparable homes; this guide doesn't assign a return percentage.
Keep planning with these related guides.
Basement Planning
Every idea here is a bar Built by Design actually built, from a beverage niche to a walk-in wine cellar. Photos, the decisions behind each, and the sizes, plumbing, and wiring that make a basement bar work.
10 min read
Johnson County Guides
Walls, wiring, plumbing, structure, additions, decks, and egress windows need a permit almost everywhere in Johnson County. Paint, flooring, and cabinet swaps usually don’t. Here’s the line, city by city, and what happens on the schedule.
9 min read
Remodel Phasing
Phasing protects cash flow and keeps the house livable. It also repeats demolition, protection, permits, and trade mobilization, and finishes drift between phases. Here's how to tell which one your project is.
9 min read
