Converting a Garage or Bonus Room in Polk County

Turning a garage or an unfinished bonus room into living space is a big value-add, and it has rules. Permits, cooling, floors and what the job really involves.

Adding living space is expensive, so the appeal of finishing a room the house already has is obvious. A two-car garage is several hundred square feet under roof. A bonus room over the garage is often framed and drywalled but never quite finished. Both can become a bedroom, an office, a gym or an in-law space. Both also come with specific requirements that a quick weekend project tends to skip, and those are what a buyer's inspector or the county will find later. Here is how the job is done properly in Polk County.

Permits first

Converting a garage to living space is a permitted job in Polk County and its cities. It changes the use of the space, and it involves electrical, often plumbing, and always the building envelope. An unpermitted conversion can be a problem at sale, with insurance, and if the county notices. The permit process also confirms the things that make the room safe and comfortable: egress, insulation, ventilation and cooling. Our post on permits in Polk County covers how the process works.

The garage door opening

The big decision is what to do with the door. Most conversions remove the garage door and frame in the opening with a wall, a window or a set of French doors, finished outside to match the house. Some homeowners keep the door for resale flexibility and build an insulated wall behind it. Either way, the new wall needs insulation, a moisture barrier and proper flashing, and the exterior finish should match the stucco or siding so the conversion does not announce itself from the street.

The floor

Garage slabs slope toward the door for drainage and sit lower than the house floor. Most conversions build a raised floor with sleepers or use a leveling system so the finished floor is level and meets the house floor without a step. The slab should be moisture tested, and a vapor barrier installed, before anything goes over it, since garage slabs were never meant to be lived on. Our post on leveling a subfloor covers the options.

Cooling, insulation and air

This is where garage conversions in Florida go wrong most often. A garage has an uninsulated block wall on three sides, an uninsulated ceiling and no conditioned air. Extending the existing AC system to the new room frequently overloads it and leaves the room hot and humid anyway. A ductless mini-split is the usual right answer: it cools and dehumidifies the room independently and does not tax the main system. Walls get furred and insulated, the ceiling gets insulation, and windows are added for light and, for a bedroom, for egress. Our post on attic heat and insulation explains why the ceiling matters so much.

Bonus rooms over the garage

A bonus room usually has the walls and ceiling but is missing some combination of insulation, adequate AC, flooring, a closet, trim and a proper stair railing. Because it sits over an unconditioned garage, the floor is hot in summer unless the garage ceiling is insulated. The AC supply to these rooms is often a single duct at the end of a long run, and a mini-split again solves that. Finishing a bonus room is a smaller job than a garage conversion since the envelope exists.

Electrical, plumbing and the rest

Living space needs more outlets than a garage has, on their own circuits, plus lighting, and a bedroom needs a smoke detector interconnected with the rest. If the plan includes a bathroom or a kitchenette, the drain has to be run through the slab, which is the biggest single cost item in most garage conversions. Where the water heater, electrical panel or laundry lives in the garage, it has to be either enclosed with proper access or relocated. A closet makes a room a bedroom for appraisal purposes. Trim, doors, paint and flooring finish it.

Parking and storage

You lose the garage. In neighborhoods with HOA rules or limited driveway space that matters, and a lot of Florida garages hold the things people do not want in the house. A storage plan, whether a shed or reworked closets, is part of an honest conversion plan. Our post on garage storage is a place to start if you decide to keep the garage after all.

Cost in the Lakeland area

A garage conversion is priced by the scope: closing the opening, floor, insulation, AC, electrical, finishes and any plumbing. It is far less than an addition of the same size and more than most homeowners expect from a "finish the garage" project once cooling and the floor are done properly. Finishing an existing bonus room is considerably less. A free estimate lays every part of it out on paper.

Inventive Home Improvement handles conversions as part of our home improvement services and carpentry in Lakeland, Haines City, Davenport and throughout Polk County. Call (863) 633-5499.

Frequently asked questions

Related reading