ADU Builder in Granite Bay
Accessory dwelling units on Granite Bay lots, designed, permitted through Placer County and built by one team.
Two ways through the county
Granite Bay is unincorporated, so an ADU here is approved by Placer County. The county runs two tracks. A state-exempt ADU meets criteria set by California law and is reviewed through the building permit alone. It is exempt from many zoning standards, including lot coverage, parking and design standards. On a single-family lot, a detached unit up to 800 square feet can qualify, as can a conversion of existing space.
A larger unit goes through the county's standards for non-exempt ADUs. That route is common, and it asks more of the design. Size, height, placement and parking all come into it, so the first decision is which track serves what you want to build.
Sewer or septic decides a great deal
Granite Bay is not uniform underground. Depending on the street, a home may be served by the county's Sewer Maintenance District 2, by South Placer Municipal Utility District, or by a septic system on the lot. That one fact often decides where an ADU can sit and what it costs to connect.
On septic, the county's updated rules allow a new structure such as an ADU to connect to an existing system when the capacity is there. Those same updates, approved in October 2025, reduced the sewer connection distance requirement to 200 feet from the structure. Both changes are worth checking on a lot that was told no years ago.
Lots, slopes and associations
Generous lots do not guarantee an easy ADU. Every foot between the unit and the main house is a foot each utility has to travel, and a lot that falls away from the sewer connection can require a lift station to pump wastewater uphill. Oaks, easements and grading can move a unit as well.
Many Granite Bay neighborhoods also have homeowners associations. California law limits an association's ability to prohibit an ADU on a single-family lot, but reasonable design rules can still apply, so we read the governing documents before a floor plan is drawn.
Designed around the person moving in
Most of the ADUs we are asked about are for family. Our first, in Fair Oaks in 2020, was a 1,200 square foot detached home for a client's mother, moving from an hour away to live beside her daughter's family and grandchildren. She was leaving an 1,800 square foot house and was nervous about the smaller space.
We studied how she used her home and designed every room around a walker, and eventually a motorized scooter. Nine-foot ceilings changed how the rooms felt, every exterior door has a near-zero threshold, and a poured switchback walkway reaches the main house without a single step. When it was finished, she told us it felt larger than the house she had left.
What to plan for
For planning purposes, a detached ADU with a professional, properly licensed builder in the Sacramento region rarely starts under $300 per square foot, and most land closer to $400 or more. Sewer distance, utility routing, site work and the mix of rooms move that number more than finishes do.
We work through those items in pre-construction, so the fixed price in your proposal reflects your lot.
Where to go next
Common questions
Can I build an ADU on my Granite Bay lot?
Usually, but the lot decides. Sewer or septic, utility routing, slope, easements and any association rules all come before a floor plan is worth drawing. That is the first conversation.
Who approves an ADU in Granite Bay?
Placer County, because Granite Bay is unincorporated. Depending on the unit, approval runs through a building permit alone or through the county's standards for non-exempt ADUs. We prepare the submittal either way.
Can an ADU use my existing septic system?
It can when the system has the capacity, under the county's updated septic rules. If capacity or records are in question, expect an evaluation before the design is final. We raise this early because it can change where the unit goes.
Can my HOA stop me from building an ADU?
California law limits an association's ability to prohibit an ADU on a single-family lot, though reasonable rules on design can still apply. We review your documents at the start so the design fits them.
K Squared Construction · 8265 Sierra College Boulevard, Suite 310, Granite Bay, CA 95746 · CSLB# 967411
Ready to talk about yours? Schedule a call or ring 916-237-8605.