Land records · Parcel maps · October 5, 2026
Can I Build an ADU on My Lot? What to Check
Can you build an ADU on your lot? Check zoning, state ADU laws, lot size, setbacks, parking, utilities, septic capacity, and HOA rules before planning.
Can I build an ADU on my lot? Many homeowners can, because a growing number of states and cities allow accessory dwelling units (ADUs), such as backyard cottages, garage apartments, and basement units, in single-family zones. Whether your specific lot qualifies depends on local zoning, any state ADU law, lot size and shape, setbacks, utilities, septic capacity if you are not on sewer, and private covenants. This page is general land-records background, not legal advice.
Types of ADUs
| Type | Description |
|---|---|
| Detached ADU | Separate small house or cottage |
| Attached ADU | Addition connected to the main house |
| Garage conversion | Living space in an existing garage |
| Above-garage unit | Apartment over a detached garage |
| Interior or basement ADU | Separate unit inside the existing home |
| Junior ADU | Small unit within the house in some states |
What to check
- Zoning and ADU ordinance: whether ADUs are allowed, and which types. See what does R1 zoning mean.
- State law: some states require cities to allow ADUs and limit local restrictions.
- Size limits: maximum square footage, often tied to lot size or the main house.
- Setbacks and height: see how to find building setbacks.
- Lot coverage: see what is lot coverage.
- Parking: some places require a space; others have eliminated parking mandates.
- Owner occupancy: some codes require the owner to live on site.
- Utilities: water, sewer, and electrical capacity and connection fees.
- Septic: added bedrooms may require septic upgrades. See how to find septic records.
- Covenants: HOA rules may restrict ADUs, though some state laws limit HOA bans. See what are CC&Rs.
Plat and easement checks
Check the recorded plat and title for easements, building lines, and no-build areas where an ADU cannot go. A survey helps place the unit accurately.
Rental rules
Many cities allow long-term rental of ADUs but restrict short-term rentals. Some require registration.
Costs to plan for
- Design and permits.
- Impact and connection fees, which some states have reduced for ADUs.
- Utility extensions.
- Construction.
Garage conversions and interior units often cost less than detached cottages.
Steps to start
- Look up your zoning and ADU rules.
- Gather your plat, survey, and septic records.
- Meet with planning staff or attend an ADU workshop if offered.
- Hire a designer familiar with local ADU rules.
- Apply for permits.
Common reasons a lot does not qualify
ADU plans most often stall because the lot is too narrow for a detached unit after side setbacks, a utility or drainage easement runs through the backyard, the septic system cannot handle more bedrooms, the lot sits in a floodway, or an HOA restriction survives state law. Sometimes the fix is a different ADU type, such as converting part of the house or the garage instead of building a separate cottage. Getting the plat, survey, and septic file in hand before paying for design avoids surprises.
Bottom line
You may be able to build an ADU on your lot if zoning or state law allows it and the lot can meet size, setback, coverage, utility, septic, and parking rules. Check covenants and plat easements, then talk with planning staff. View your parcel on the Platbookmapper map.
Can i build an adu on my lot FAQ
What is an ADU?
An accessory dwelling unit, a secondary home on a single-family lot.
Are ADUs allowed in single-family zones?
Increasingly yes, through local ordinances and state laws.
Can my HOA ban an ADU?
Some can, though certain state laws limit HOA restrictions.
Do I need extra parking for an ADU?
It depends on local rules; many places have reduced or eliminated requirements.
Can I rent out an ADU?
Long-term rentals are often allowed; short-term rentals may be restricted.