ADU Cost Calculator for Salt Lake City: What You'll Really Pay to Build in 2026

Why ADU Costs Vary in Salt Lake City

Understanding what drives ADU pricing helps you make informed decisions and budget accurately for your project.

Every ADU project is unique. Your costs depend on your property’s characteristics, the type of ADU you build, your finish choices, and Salt Lake City’s specific requirements. Here’s what influences your investment.

Type of ADU (Detached, Attached, Garage Conversion, Basement ADU)

Detached new construction ADUs cost the most at $250-$400+ per square foot because you’re building a complete structure from the ground up—foundation, framing, roof, full systems, and all finishes. You’re creating an entirely new building on your property.

Garage conversion ADUs offer the best value at $100-$200 per square foot since you already have the foundation, walls, and roof. Investment focuses on insulation, interior finishes, and adding kitchen and bathroom systems. Perfect if you have an underutilized garage and can park elsewhere.

Basement conversion ADUs are most affordable at $80-$150 per square foot when you have existing basement space. Major costs involve adding required egress windows, creating a separate entrance, and finishing the interior. Must meet ceiling height requirements (typically 7 feet minimum).

Attached addition ADUs fall in the middle at $200-$350 per square foot. You share one wall with your main house, which reduces some costs compared to detached, and utility connections are simpler since you’re building adjacent to existing systems.

Lot Size & Zoning Requirements

Salt Lake City zoning determines whether an ADU is even possible on your property and what size you can build. Most single-family zones allow ADUs up to 1,000-1,200 square feet or 50% of your main dwelling size, whichever is less.

Setback requirements typically mandate 5-10 feet from rear and side property lines. Smaller lots may not have adequate space for a detached ADU after accounting for setbacks, making garage or basement conversions the only option.

Lot coverage limits restrict how much of your lot can be covered by structures—usually 40-50% total for main house plus ADU. Properties in historic districts like the Avenues face additional design review that adds 2-6 weeks to permitting and may require specific exterior materials or architectural styles.

Parking requirements vary by jurisdiction. Some areas require one additional off-street parking space for the ADU. Properties near transit lines may have reduced parking requirements.

Foundation & Utility Connection Costs

Salt Lake City’s clay soil presents foundation challenges. Clay expands when wet and contracts when dry, requiring engineered foundations with proper drainage systems. Foundation costs range $15,000-$40,000 depending on site conditions and ADU size.

Utility distance dramatically impacts costs. Running electrical, water, and sewer lines 20 feet from your main house to a backyard ADU costs $3,000-$6,000. Running those same utilities 100+ feet adds $12,000-$18,000 for extensive trenching and materials.

Older neighborhoods in Sugar House, Avenues, and Murray sometimes have undersized utility mains. Upgrading water or sewer connections to handle additional load can add $8,000-$25,000 in unexpected costs. Always have utilities evaluated early in planning.

Separate meters cost $1,500-$3,000 but simplify rental situations by allowing tenants to pay their own utilities directly. Worth the investment if you plan to rent your ADU long-term.

Permitting & Local Development Standards

Salt Lake City requires full building permits for all ADUs. The permitting process takes 3-6 months and involves zoning approval, plan review, multiple inspections, and final certificate of occupancy.

Permit fees themselves range $2,000-$5,000. Impact fees—charges for the ADU’s impact on city infrastructure like roads, parks, and utilities—add another $3,000-$10,000 depending on jurisdiction. Some Salt Lake County cities have reduced or waived ADU impact fees to encourage affordable housing development.

Design review in historic districts adds time and potentially cost if you’re required to use specific materials or architectural details that match neighborhood character. Plan review fees run $500-$1,500 for the city to evaluate your plans for code compliance.

Inspection fees ($300-$800 total) cover multiple visits throughout construction: foundation, framing, rough-in (electrical/plumbing/HVAC), insulation, and final inspection.

Size, Layout & Design Complexity

Square footage is the primary size-related cost driver. A 400 square foot studio ADU costs $100,000-$160,000 (detached). An 800 square foot one-bedroom runs $200,000-$320,000. Double the size, roughly double the cost.

Layout complexity affects pricing. Simple rectangular floor plans with straightforward plumbing and electrical are most economical. Custom layouts with angled walls, vaulted ceilings, or complex rooflines add 15-25% to construction costs.

Number of bathrooms significantly impacts budget. One bathroom runs $18,000-$25,000 installed. Adding a second bathroom for a two-bedroom ADU adds another $15,000-$22,000.

Kitchen size matters too. A basic kitchenette with sink, mini-fridge, and microwave costs $8,000-$12,000. A full kitchen with range, full-size refrigerator, dishwasher, and extensive cabinets runs $15,000-$25,000.

Outdoor spaces like decks or patios add $3,000-$10,000 depending on size and materials but greatly enhance livability and rental appeal.

Labor & Material Costs in the Salt Lake Market

Salt Lake City’s construction market experiences seasonal fluctuations. Summer months (May-September) see peak demand—contractors are busy, and prices reflect it. Winter construction (November-February) slows due to weather but may offer better pricing from contractors seeking work during slow season.

Skilled labor rates in Salt Lake City run $50-$85 per hour for licensed tradespeople. Electricians charge $75-$120 per hour. Plumbers run $80-$130 per hour. These rates reflect fair compensation for experienced professionals, not the inflated pricing of big construction companies.

Material costs fluctuate with national supply chains but local factors matter too. Lumber prices spiked during 2020-2021 but have stabilized. Transportation costs to Utah affect pricing—we’re not near major ports or manufacturing centers, so materials travel farther.

Contractor availability impacts pricing. Salt Lake City’s strong housing market keeps good builders busy. Quality ADU specialists—contractors who’ve built dozens of ADUs and understand permitting inside and out—command fair rates because their expertise prevents costly mistakes and delays.

The difference between a skilled local builder and a general contractor treating ADUs as a side project can be $40,000-$80,000 in your final cost due to efficiency, relationships with subcontractors, and avoiding permit delays or rework.