Many homeowners wonder if they can build a mother-in-law suite in their backyard. A mother-in-law suite is a small, separate living space added on or near the main house. It gives extra room for aging parents or other families. Building one can allow loved ones to live close by with some privacy. A backyard is a good spot because it is near the home.
Some municipalities allow building mother-in-law suites if the suite is not too big and has its parking. It must look nice and match the main home. Check the rules from your local government first before starting. With the right permits, a backyard could be a great place for a mother-in-law suite that benefits the whole family.
What is a Mother-in-Law Suite?
A mother-in-law suite, sometimes called an accessory dwelling unit, granny flat, or backyard cottage, is a small, independent residential dwelling on the same property as a single-family home. Mother-in-law suites provide living quarters for aging parents or other family members while maintaining independence from the main house.
A mother-in-law suite typically includes a small kitchen or kitchenette, bathroom, living/bedroom space, and possibly a separate entrance. The suite is essentially a standalone apartment attached to or near the main house. This living arrangement allows older relatives or adult children to live comfortably on your property while having privacy.
Can I Build a Mother-in-Law Suite on My Property?
The regulations around building mother-in-law suites can vary depending on your location. In general, most residential zones will allow the construction of an ADU as long as it complies with size, parking, and other design restrictions set by your municipality. However, some neighborhoods may have homeowner association rules prohibiting mother-in-law suites.
To find out if you are legally permitted to build an ADU on your land, check with your local planning/zoning department. You will likely need to obtain building permits before starting construction of the unit. Regulations often specify that the ADU must be secondary to the main house in size and have adequate parking and land area. The suite may have maximum square footage limits of 750-1,000 square feet depending on your city codes.
Some things to consider when determining if your property can accommodate a mother-in-law suite include:
- Lot size: Most communities require a minimum lot size, usually around 5,000-10,000 square feet.
- Setbacks: The ADU needs to adhere to the required front, side, and rear setbacks from property lines.
- Parking: One additional off-street parking space may be mandated per bedroom.
- Appearance: The suite should look like an extension of the main residence and match architectural features/materials.
How to Build a Mother-in-Law Suite?
There are several construction options for building a mother-in-law suite:
- detached building: A separate auxiliary structure was built some distance from the main house. This provides the most independence but may require additional permits and have higher building costs.
- attached building: Built onto an existing structure like a garage. Can share some walls with the main house for easier construction.
- internal conversion: Remodeling an underutilized space within the existing home footprint, like a basement or above-garage area, into a self-contained unit.
- prefab/manufactured home: Purchasing a modular or tiny home that can be delivered and installed onsite. It may have a smaller footprint.
Regardless of the construction method, the general mother-in-law suite building process involves:
- Hiring an architect: Get plans drawn up showing electrical, plumbing, and framing layouts that meet the code.
- Obtaining permits: Submit building plans to local authorities for review and permitting.
- Site preparation: Establish property lines, and install drainage and utility hookups.
- Foundation pours: Lay concrete footings and slab or basement walls.
- Framing: Erect wooden frames for walls, and roof and install decking.
- Insulation and vapor barrier: Add batt insulation and moisture barrier.
- Drywall and finishes: Hang drywall, and install trim, doors, windows, and cabinets.
- Mechanical systems: Plumb sink/toilet, run ductwork, and install HVAC equipment.
- Final inspection: Have the municipal inspector sign off before occupancy.
Frequently Asked Questions
One of the most affordable approaches is to do an internal conversion of existing space like a basement or attic. Using the existing house foundations and infrastructure keeps costs down.
The timeline can vary significantly based on the size and type of build. On average, plan for about 6-9 months to complete an attached ADU that requires a concrete foundation. An internal conversion or a smaller detached building may only take 3-6 months.
Yes, a mother-in-law suites can provide returns both financially and personally. Renting out the ADU long-term can generate rental income to offset construction costs. It also increases your property value given the additional living space.
In addition to supplemental income potential from renting, a mother-in-law suite appreciably increases the square footage of a home. This enhances curb appeal and property value. It also provides flexibility, allowing multigenerational living or use as a dedicated guest house.
Common uses of a mother-in-law flat beyond just housing family include rental income property, guest quarters, home office, art studio, teenager apartment, or au pair/nanny lodgings.
Conclusion
A mother-in-law suite can be a valuable addition for any homeowner interested in multigenerational living, gaining extra living space, or producing rental income. With careful planning to meet all local codes and regulations, it is possible to build an ADU on many residential properties.
Consider your budget, timeline, and intended purpose for housing family members or tenants when choosing construction materials and sizes. An internal conversion may be faster and more cost-effective, while a detached casita allows absolute independence. Prefabricated modular units provide another affordable turnkey option.
Do thorough research into your area’s zoning laws to understand permitted ADU sizes, setback requirements, and parking regulations. Also factor in costs for plans, permits, utility hookups, and build-out finishes to budget appropriately. Following the proper planning process from hiring an architect to finishing touches helps ensure successful occupancy.
