An attached garage already has a foundation, walls and a roof, so it can seem like an easy place for an in-law suite. It can work well, but a garage is built for cars, not people. Turning it into comfortable living space takes careful planning.
Check local rules first
Before designing anything, find out what your community allows. Some places limit separate living units in single-family homes or have rules about kitchens, separate entrances and off-street parking. Losing a garage can affect parking requirements in some neighborhoods. A garage conversion also typically needs a building permit.
The floor
Garage floors are usually concrete slabs set lower than the floor of the house, and they often slope toward the door so water drains out. Most conversions need a plan to level the floor, keep moisture out and insulate it. That may mean a raised subfloor or other approaches, and it affects ceiling height and the step into the main house.
Walls, ceiling and insulation
Garage walls and ceilings are often uninsulated. To make the suite comfortable through a Michigan winter, walls, ceiling and any exposed areas need insulation and air sealing like the rest of the home.
The garage door opening
The large door opening is usually framed in to create a wall with a window or door. The outside should be finished to match the house, so the conversion looks planned rather than patched.
Heating, cooling and utilities
Think about how the suite will be heated and cooled. Your existing system may be able to serve it, or a separate unit may make more sense. If the suite will have a bathroom or kitchenette, plan how plumbing will reach it and where drains will run, since the slab can make this more involved.
Light, safety and comfort
A garage often has few windows. Adding windows brings in daylight and fresh air, and a sleeping room needs an emergency escape opening under building codes. Plan smoke and carbon monoxide alarms, and think about sound between the suite and the main house.
Accessibility
A garage is often on the same level as the driveway, which can make a step-free entry possible. If the suite is for an aging parent, consider wider doorways, a curbless shower and wall blocking for future grab bars.
Where will the cars and storage go?
Finally, plan for what the garage holds today. Vehicles, tools, bikes and seasonal items will need a new home.
Explore how we plan in-law suites.
