ADU Design Cost: Architect vs. Pre-Approved Plans
ADU design cost: what architects, designers and pre-approved plans charge, how fees work, and how to choose for your lot.
ADU Costs
ADU costs depend on the state, the city, the unit type and your lot. These guides show what ADUs really cost to build in the United States: construction ranges, budgets, utility hookups, design fees and local charges, with the source behind every figure.
The Cheapest Way to Build an ADU Without Cutting Corners
Cheapest way to build an ADU in California: convert space, stay under fee limits, use pre-approved plans, keep utilities short.
ADU Cost in Portland: SDCs, the 10-Year Waiver and Permit Fees
Portland ADU cost: FY 2026-27 SDCs, the 10-year short-term-rental waiver and permit fees, with what to budget.
Seattle ADU Fees: Permit, Sewer Capacity and Utility Charges
Seattle ADU fees: SDCI permit fees, King County’s sewer capacity charge, SPU development charges and pre-approved plans.
How Much Does an ADU Cost in California? 2026 Ranges by Type and Size
ADU cost in California: the 2021 owner survey median, 2026 builder ranges by type and size, and why per-foot prices mislead.
ADU Budget Breakdown: Three Sample Budgets and a Line-by-Line Framework
Three sample ADU budgets (400, 600 and 800 sq ft) with the arithmetic shown, plus the five budget blocks and what to ask each bidder.
Hidden ADU Costs and Utility Hookups: Sewer, Water, Electric and Agency Fees
Hidden ADU costs: sewer, water and electric hookup ranges, site conditions, agency fees and a worked example.