This guide walks you through everything you need to know: what qualifies as a legal ADU, how to plan and permit one in Tooele County, what the build process looks like, and how to calculate your return on investment. Whether you are thinking about it or ready to break ground, Upterra Builders is here to help.
What is a basement ADU and why does it matter?
An accessory dwelling unit (ADU) is a self-contained living space on the same property as a primary residence. A basement ADU is one of the most cost-effective types because the structure already exists. You are not building from the ground up, you are finishing space you already own.
A legal basement ADU typically includes:
- A private entrance, separate from the main home
- A full kitchen or kitchenette
- A bathroom with shower or tub
- A bedroom or sleeping area
- Proper egress windows for safety
When done right, a finished basement ADU can rent for roughly $900 to $1,500 per month in the Tooele County market, depending on size and finish level.
Why Tooele County is the right place to do this right now
Tooele County is one of Utah's fastest-growing areas. As families and workers move out from the Salt Lake Valley seeking more affordable housing, demand for rentals in Tooele City, Stansbury Park, Grantsville, and surrounding communities has increased significantly.
Here is why that matters for you as a homeowner:
- Low vacancy rates mean your unit is unlikely to sit empty
- Rising home values mean your ADU adds equity on top of rental income
- New construction volume in the county has increased interest in ADU-specific permitting and inspections, so local contractors who know the process are in high demand
- Utah state law (HB 462, 2022) has pushed municipalities to allow ADUs more broadly, making it easier than ever to get approved
Upterra Builders works specifically in Tooele County. We know the local codes, the permit office, the inspectors, and what it takes to get your project approved and completed without costly delays.
Step 1: Check your zoning and HOA rules
Before you invest a dollar in design or planning, confirm that your property is zoned to allow an ADU. In Tooele County:
- Most residential zones (R-1, R-2, and similar) allow ADUs
- Some communities have HOA restrictions that are separate from county zoning, so check your CC&Rs
- Properties must typically be owner-occupied to qualify for an ADU permit in many jurisdictions
If you are unsure, Upterra Builders can walk you through a pre-permit assessment at no obligation. We have done this dozens of times and can save you weeks of back-and-forth with the county.
Step 2: Understand the Tooele County ADU requirements
Every ADU in Tooele County must meet a set of minimum requirements before the county will issue permits. These include:
Size and layout requirements
- Minimum square footage varies by zone, but most basement ADUs need at least 400 sq ft of livable space
- Ceiling height must meet minimum standards (typically 7 feet for habitable space)
- Egress windows are required in any sleeping area. This is a life-safety requirement that cannot be skipped
Separate entrance
Your ADU must have its own entry point, independent from the main home. This can be an exterior stairwell, a walkout basement door, or a side entrance. Upterra Builders designs entrances that maintain privacy for both the homeowner and the tenant.
Mechanical, electrical, and plumbing
The ADU needs its own or shared mechanical systems that meet current code:
- HVAC capable of heating and cooling the space independently
- Updated electrical panel capacity (most homes need an upgrade)
- Full plumbing for kitchen and bathroom
Fire and safety code
- Smoke and CO detectors throughout
- Proper fire separation between the ADU and the main home
- Egress compliance in all sleeping areas
Step 3: Design your space
Good design is what turns a compliant basement into a space tenants love, and want to stay in long-term. Upterra Builders approaches basement ADU design with two goals: maximize livable square footage and create a space that rents at the top of the market.
Key design decisions to make:
Bedroom configuration. One bedroom is easiest to permit and furnish, but a 2-bedroom ADU can command significantly higher rent. We will assess your basement footprint and recommend the layout that best balances permittability and rental value.
Kitchen vs. kitchenette. A full kitchen (with a range, sink, and full-size refrigerator) appeals to long-term tenants. A kitchenette is faster to build and costs less. We will help you choose based on your goals.
Natural light. Basements often feel dark. Egress window wells, light tunnels, and strategic lighting design can transform the feel of the space. Tenants notice, and they will pay more for a basement that does not feel like a basement.
Storage. Tenants in smaller units care deeply about storage. Built-in closets, under-stair storage, and smart shelving are worth including from the start.
Step 4: Permitting and inspections
This is where many DIY projects and inexperienced contractors stall. Basement ADU permits in Tooele County require:
- Site plan showing the ADU location on your lot
- Floor plan with dimensions, room labels, and egress windows
- Elevation drawings if exterior changes are involved (like a new entrance)
- Mechanical, electrical, and plumbing plans reviewed separately
- Energy compliance documentation (Utah follows IECC energy codes)
After permit approval, your project will go through multiple inspections: rough framing, rough electrical, rough plumbing, insulation, and final. Missing an inspection or failing one adds time and cost.
Upterra Builders manages the permitting process for every ADU we build. We submit your plans, coordinate with county reviewers, address any revision requests, and schedule all inspections. You do not have to navigate the bureaucracy, we do it for you.
Step 5: Construction
Here is what the actual build process looks like for a typical basement ADU with Upterra Builders:
Week 1 to 2: Demo and rough-in prep. Remove any existing walls that do not match the new layout. Open ceilings and walls for mechanical rough-in. Cut egress window openings if needed.
Week 2 to 4: Rough mechanical, electrical, and plumbing. Our licensed subcontractors run all new HVAC ductwork or mini-split lines, plumbing for kitchen and bath, and electrical circuits for the new unit. Rough inspections happen at the end of this phase.
Week 4 to 5: Insulation and framing. Insulate exterior walls, install vapor barriers, and frame any remaining walls. Insulation inspection occurs here.
Week 5 to 8: Drywall, flooring, and finishes. Hang and finish drywall, install flooring (LVP is our most popular choice for basement ADUs because it is durable, waterproof, and looks great), paint, and begin trim work.
Week 8 to 10: Kitchen, bathroom, and fixtures. Install cabinets, countertops, and fixtures in kitchen and bath. Set appliances. Install lighting, outlets, and switches.
Week 10: Final inspection and punch list. County final inspection. Address any punch list items. Hand over keys.
Most basement ADU projects with Upterra Builders are completed in 10 to 14 weeks, depending on scope and permit timelines.
How much does a basement ADU cost in Tooele County?
Basement ADU costs vary based on square footage, existing conditions, and finish level. Here is a general range:
- Basic 1-bed/1-bath ADU (400 to 600 sq ft): $55,000 to $75,000
- Mid-range 1-bed/1-bath ADU (600 to 800 sq ft): $75,000 to $100,000
- Premium 2-bed/1-bath ADU (800 to 1,100 sq ft): $100,000 to $140,000
Costs can be higher if electrical panel upgrades, egress excavation, or significant plumbing relocation is required. These numbers may seem significant, but consider the return.
What is the return on investment?
Let us run a simple example:
- ADU build cost: $85,000
- Monthly rent (1-bed in Tooele County): $1,100 per month
- Annual rental income: $13,200 per year
- Simple payback period: about 6.4 years
After payback, that is $13,200 or more per year in additional income from space you were not using, plus the ADU adds equity to your home that you would recoup if you ever sell. Many homeowners also use the ADU income to offset their mortgage, making homeownership significantly more affordable in the process.
Who is a basement ADU right for?
A basement ADU makes the most sense if you:
- Own a home in Tooele County with an unfinished or underutilized basement
- Want to generate rental income without buying a second property
- Have adult children or aging parents you want nearby (multigenerational living)
- Plan to stay in your home long-term and want to build equity faster
- Are interested in house hacking, using rental income to reduce your housing costs
Why choose Upterra Builders for your basement ADU?
There are a lot of contractors in Utah. Here is what sets Upterra Builders apart for ADU projects specifically:
Local expertise. We work in Tooele County. We know the permit office, the code requirements, and the inspectors. We have navigated this process many times and will not be learning on your project.
Full-service. From initial design consultation through final inspection, Upterra Builders manages every phase. You do not have to coordinate multiple contractors or chase down permits yourself.
Transparent pricing. We provide detailed estimates before we start, and we do not hide costs in change orders. What we quote is what you pay, barring genuine unforeseen conditions.
Quality finishes. We build ADUs that rent, which means attractive, durable finishes that attract quality tenants and hold up over time.
ADU-specific experience. Not every contractor has done an ADU before. We have. We understand the nuances of egress, fire separation, independent mechanicals, and the other details that make the difference between a project that passes inspection and one that does not.
Frequently asked questions
Do I need to live in the home to have a basement ADU in Tooele County?
In most cases, yes. Owner-occupancy is a common requirement for ADU permits. Upterra Builders will confirm the specific requirements for your property before we begin.
How long does the permit process take?
Permit review timelines vary but typically range from 4 to 8 weeks in Tooele County. We submit complete, well-prepared packages to minimize revision requests and delays.
Can I use my ADU for short-term rentals like Airbnb?
Short-term rental rules are separate from ADU permitting and depend on local ordinances. We recommend confirming short-term rental allowances with Tooele County before planning around that use case.
What if my basement has low ceilings?
Ceiling height requirements (typically 7 feet for habitable space) can sometimes be addressed through underpinning or lowering the basement floor. This adds cost but is sometimes worth it depending on your basement's potential. We will assess this during your consultation.
Will a basement ADU affect my property taxes?
Adding livable square footage typically does affect assessed value, and therefore property taxes. The rental income typically more than offsets this increase, but it is worth factoring into your ROI calculations.
Upterra Builders serves homeowners throughout Utah, specializing in basement finishing, remodeling, home additions, and commercial tenant improvements. All projects are permitted and built to Utah IRC standards. We serve Tooele, Stansbury Park, Grantsville, Stockton, Erda, and surrounding Tooele County communities. Licensed and insured in Utah.