Build a Detached ADU — The Right Way
A custom detached ADU gives you maximum design flexibility, the strongest ROI, and a fully separate living space. We handle everything from lot assessment to final walkthrough.
Why Build a Detached ADU?
A detached ADU — sometimes called a backyard cottage, carriage house, or accessory unit — is a fully independent structure built separate from your primary home. It has its own entrance, living space, kitchen, and bathroom, making it the most versatile and most valuable type of ADU.
Detached ADUs typically command higher rents, add more property value, and give both the homeowner and the ADU occupant more privacy than attached or garage-conversion options. The trade-off: they cost more and take longer to build. Our job is to make sure the investment pays off.
Detached ADU Size Options
Studio / 1-Bath
400–550 sq ft
Open-concept living and sleeping with full kitchen and bathroom. Ideal for single occupants or short-term rental.
From ~$120,000
1-Bedroom / 1-Bath
550–750 sq ft
Private bedroom, open living area, full kitchen and bath. Most popular for long-term rental or aging parents.
From ~$150,000
2-Bedroom / 1–2 Bath
800–1,200 sq ft
Two full bedrooms, separate living area, full kitchen. Maximum rental income and property value impact.
From ~$200,000
Twin Falls Code: Detached ADU Requirements
- →45% Rule: Per Title 10-6-10-B, your ADU cannot exceed 45% of your principal residence's living space. A 2,000 sq ft home = max 900 sq ft ADU.
- →Setbacks (under 15 ft height): 20 ft front, 3 ft side, 3 ft rear — across all zoning districts.
- →Setbacks (over 15 ft height): 20 ft front, 5–7 ft side, 15–20 ft rear depending on district (TN-1, TN-2, TN-3, R-2, RR).
- →Design Match: Must be consistent with the existing roof pitch, siding, and windows of your principal dwelling.
- →Shared Utilities: Must share water, sewer, and sanitation with primary home — no separate meters per Title 10-6-10-B(vii).
- →Parking: One additional parking space required for exclusive ADU use.
Already Have Floor Plans? Bring Them.
If you already have plans or a design in mind, we can review them for buildability and Twin Falls code compliance. We can also take existing plans and produce the permit-ready stamped drawings required by the City. Browse our pre-designed floor plans →
How We Build Your Detached ADU
A proven 4-step process designed to prevent surprises
Feasibility Check
We measure your lot, verify setbacks for your zoning district, calculate the 45% size limit, assess utility access, and determine the best placement for a detached ADU on your specific property.
Custom Design
Our design team creates a floor plan and elevations tailored to your lot, your goals, and your main home's exterior. Plans are stamped and permit-ready.
Permitting
We submit and manage all permit applications — Zoning Use Permit, building permits, and trade permits for electrical, plumbing, and mechanical. We handle every interaction with the city.
Construction
Foundation, framing, roofing, mechanical, interior, and exterior finishes — all handled by our licensed team. We manage every inspection and deliver a Certificate of Occupancy.
Is Your Lot Ready for a Detached ADU?
Book a free 10-15 minute Readiness Call. We'll quickly assess your lot size, zoning district, and 45% size limit — and tell you honestly what's possible.