How To Add an In-Law Suite to Your Home (2024) (2024)

Converting an unfinished basem*nt into an in-law suite can be cost-effective,* as it typically requires less renovation and construction than other options. However, you’ll need to account for the following:

• Height of the ceiling: Ideally, the basem*nt ceiling should be at least 7 feet high to accommodate an in-law suite. This is high enough to feel spacious and to provide adequate headroom for occupants to move around comfortably. If the ceiling is lower than 7 feet, you may need to excavate the basem*nt to increase its height. This will add to the cost and complexity of the project.
• Presence of windows: Windows provide natural light, which can help the space feel more open and airy. They can also be used as emergency exits in case of a fire. If the basem*nt does not have windows, install several to enhance safety and keep the space from feeling claustrophobic. Consider using top quality window brands for your project.
• Potential for mold: Basem*nts are often damp, which can lead to the growth of mold and other harmful substances. To prevent mold, it’s important to waterproof and properly ventilate the basem*nt. Allowing air to circulate will prevent moisture buildup. You may also need to install a dehumidifier, French drains, or a sump pump.

* According to HomeAdvisor, a basem*nt conversion can cost anywhere from $12,000–$34,000.

Converting an attic into an in-law suite is not as common as converting a basem*nt, but it can be a viable option if your house has a large attic. Here are some important considerations when converting an attic into an in-law suite:

• Ceiling height: The ceiling in your in-law suite should be at least 7 feet high for ease of movement and spaciousness. If your attic ceiling is lower than that, you may need to raise the roof or install a dormer to increase its height.
• Natural light: As you divide the attic into distinct areas, ensure each room has a window or skylight, if possible. Windows will provide natural light and ventilation throughout the space.
• Accessibility: To ensure your in-law suite has its own entrance, you must install an exterior door and a sturdy staircase leading up to it. You might also consider having a sturdy and accessible interior entrance leading into the rest of the house.
• Ventilation: Like basem*nts, attics are prone to mold, mildew, and issues resulting from moisture and a lack of air circulation. You may need to install a dehumidifier or attic fan to help with ventilation.
• Insulation: Because hot air rises, attics can become overly warm in the summer. Without proper insulation, they can also become very cold in the winter. High-quality insulation will help keep out unconditioned air and ensure a comfortable temperature year-round.

According to SoFi, finishing a walk-up attic can cost $8,100–$26,000.

Converting a garage into an in-law suite can be practical if you do not need that space for vehicle parking. You can do this with either an attached or detached garage. A detached garage allows you to build an apartment above the garage, which lets you retain your covered parking spaces. Here are a few things to consider when converting a garage into an in-law suite:

• Structure: Before converting your garage into a living space, make sure it’s structurally sound. Inspect the foundation, walls, and roof to see if anything needs to be reinforced, repaired, or rebuilt.
• Insulation: While attics tend to get hot and humid, garages often feel cold and drafty. High-quality insulation can help prevent heat loss in the winter and heat gain in the summer.
• Utilities: Chances are, your garage does not have its own plumbing. In that case, you must install a plumbing system to accommodate the kitchen and bathroom. You should also ensure the garage has a separate electrical panel and sufficient outlets.
• Access: Most garages already have a separate entrance. However, if you build an in-law suite above your detached garage, you must add a new door and a staircase to the second level.

According to HouseLogic, converting a two-car garage into a living space with a bathroom can cost $35,000–$75,000.

If you do not have a basem*nt, attic, or garage, you may be able to convert other rooms into an in-law suite. This works especially well if your kids have already moved out. In that case, you can easily move your parents into those rooms. First-floor rooms are ideal, as they will be more accessible for occupants with mobility issues.

One option is to reconfigure extra bedrooms to build an in-law suite. If you only have one bedroom with an attached bathroom, you may need to add a bathroom or convert an existing one into an en-suite bathroom. You might also be able to knock down a wall to create a large suite or cut a new doorway to join two rooms into one suite.

Another option is to remodel a different finished space, such as a family room or rec room. If you already have a finished attic or basem*nt, for instance, adding an in-law suite will be that much easier.