4 places to put an in-law suite
| Option | Privacy | Change to the plan |
|---|---|---|
| Convert a bedroom wing — bedroom + bath at one end of the house become a suite | Medium | Smallest; mostly interior |
| Main-floor addition — a wing added to the side or back | High | Footprint, roof and foundation grow |
| Over the garage — suite in the bonus space above | High | Stair, roof and possibly garage framing change |
| Walkout basement — a lower-level suite with its own door to the yard | Highest | New level (see adding a basement) |
For a parent who will age in place, a main-floor suite is almost always the right answer. Stairs are the first thing that stops working.
What a good in-law suite includes
- A bedroom that fits a queen or king bed plus a chair, with an egress window.
- A private bathroom — ideally with a curbless or low-threshold shower.
- A sitting area so the suite isn't just a bedroom — a place for TV, reading and visitors.
- A kitchenette — sink, under-counter fridge, microwave. (A full kitchen with a range may change how your city classifies the space — see below.)
- Its own entrance, or at least a door that doesn't pass through the main living area.
- Sound separation — closets or baths as buffers between the suite and the main bedrooms.
- Separate HVAC zone or a mini-split so everyone sets their own temperature.
A compact but comfortable suite is roughly 400–600 sq ft. Ideas: house plans with an in-law suite.
Designing the suite for aging in place
If the suite is for a parent, design it for the next 20 years, not just move-in day:
- 36″ doors and at least 42″ halls for walkers and wheelchairs.
- A 5-foot turning circle in the bathroom and beside the bed.
- No steps from the driveway or garage to the suite.
- Blocking in bathroom walls for grab bars now, even if you install them later.
- Lever handles, good lighting, and outlets at reachable heights.
In-law suite vs. ADU: where the zoning line is
Many cities treat a suite that has its own full kitchen and separate entrance as a second dwelling unit (an ADU or accessory apartment), which can trigger different zoning rules, utility connections and fees. A suite with a kitchenette that's part of the main house is usually treated as part of a single-family home.
Want a fully separate unit instead? See house plans with a casita and can I build an ADU on my property?
Privacy, shared spaces and layouts that work for three generations under one roof.
Read the guideWhat adding an in-law suite costs
| Change | Our package |
|---|---|
| Convert an existing bedroom wing into a suite | Standard Modification — $599 |
| Main-floor addition, suite over the garage, or basement suite | Major Plan Redesign — from $999 |
| MEP update (plumbing, electrical, HVAC for the suite) | +$299 |
Construction cost rises with the added heated square footage, the extra bathroom and any kitchenette. A cost-to-build estimate (+$99) prices the modified plan for your state.
How to get an in-law suite added to your plan
- Upload your plan — any plan you own or have the right to modify.
- Tell us who it's for — mobility needs, privacy level, kitchenette or not, possible future rental.
- We confirm scope within 1 business day and recommend the best location.
- We redraw the plan with two revision rounds included.
Frequently asked questions
Can you add an in-law suite to an existing house plan?
Yes. We convert a bedroom wing, add a main-floor wing, put a suite over the garage, or add a walkout basement suite — depending on your lot and who the suite is for.
How big should an in-law suite be?
A comfortable suite with bedroom, private bath and sitting area is roughly 400–600 sq ft. A kitchenette adds a little more.
Is an in-law suite the same as an ADU?
Not always. Many cities treat a suite with a full kitchen and separate entrance as a separate dwelling unit with different rules. A suite with a kitchenette inside the main house is usually part of the single-family home. Check your local definition.
How much does it cost to add an in-law suite to a plan?
Converting an existing wing is a Standard Modification at $599. An addition, suite over the garage or basement suite is a Major Plan Redesign from $999.
Can you modify a plan I bought from another website?
Yes — provided you own the plan or have permission / the right to modify it.