How long to build an ADU or tiny home in Utah?
Plan on about four to six months from the first conversation to move-in. That window covers architecture and design, city permitting and plan review, and then construction. Tiny homes are built in our Lehi shop and delivered, so weather and site work rarely slow them down. On-site ADUs follow the same arc but add excavation, utility connections, and inspections, which is where most schedule variation shows up.
The four-to six-month arc, broken into three parts
Almost every project we build in Utah follows the same three phases, and knowing where the time goes makes the wait far less frustrating.
Design and architecture usually takes the first stretch. This is where you settle square footage, layout, window placement, kitchen and bath configuration, and where the unit sits on your lot. If you already know what you want — say you walked one of our model homes in Lehi and said "that one, with a bigger shower" — this phase moves quickly. If you want a heavily customized floor plan, expect more back-and-forth. Time spent here is cheap compared to changes made later, so it's worth being decisive but thorough.
City permitting comes next, and it's the phase we control the least. Plans go to the city for review, the city responds with comments, we revise, and the permit issues. Every city along the Wasatch Front handles this differently — some are quick and predictable, others take longer or ask for more detail on setbacks, parking, or utility capacity. What the city will and won't approve is the city's call, not ours, which is why we start conversations with the planning counter early rather than after drawings are finished.
Construction is the last phase and the most visible. For a shop-built tiny home, this means framing, mechanical, electrical, plumbing, finishes, and inspection on our floor in Lehi, then delivery and set. For an on-site ADU, it means our local crew working on your property through foundation, framing, rough-ins, inspections, drywall, and finish work.
Why shop-built tiny homes usually run faster
A tiny home built indoors doesn't care that it snowed in March or that the ground froze in January. Materials stay dry, tools stay in one place, and the crew isn't driving between job sites. That controlled environment is the single biggest reason prefab construction tends to compress the schedule compared with traditional site building.
There's another advantage: while the home is being built in the shop, your site work can happen in parallel. Pad prep, a driveway, and utility stubs can all move forward at the same time rather than in sequence. On a site-built project, those steps have to finish before framing starts.
Delivery day itself is short — often a single day for placement — but it needs planning. Access matters. A narrow driveway, a tight turn, low power lines, or a steep grade all shape how a unit gets set. We look at that early so there are no surprises when the trailer arrives.
What actually makes a project take longer
Permitting is the most common source of delay, and it's rarely dramatic — usually it's a round of city comments that adds a few weeks. Utility connections are the second. If a sewer lateral is far from the ADU location, or if the electrical service on an older home needs an upgrade to carry a second dwelling, that adds real time and cost.
Site conditions matter more than people expect. Rock, a high water table, a steep backyard, or mature trees you want to save all affect excavation and foundation work. So does access: if a mini excavator can't get to the back of the lot, the work gets slower and more manual.
Then there are decisions. Late changes to a floor plan, long-lead finishes, or an undecided kitchen layout can stall a build that was otherwise on schedule. This is why we push clients to lock the layout before permitting. Thinking through how a floor plan matches your daily routine early is the cheapest schedule insurance there is.
Cost drivers and schedule drivers overlap heavily. Complex rooflines, custom cabinetry, extensive site work, and premium finishes all push both numbers up. Simpler shapes and proven layouts keep both in check.
How to start so the clock starts sooner
The fastest projects begin with three things settled: what you want the unit to do, roughly where it goes on your property, and what your city allows on that parcel. Rental income, a place for aging parents, a home office, or a guest suite all lead to different layouts and different permitting paths.
Walking a real home helps more than any brochure. We keep model homes in Lehi you can step inside — the 30-footer (our middle size) — and ten minutes standing in a kitchen tells you more about ceiling height and counter space than any drawing. If you're weighing this against buying, our guide to small homes and the Lehi housing market puts the tradeoffs side by side.
Finally, build a little slack into your own plans. If you need a unit ready for a family member arriving in the spring, start in the fall. Four to six months is a realistic range, not a promise for every lot in every city, and the projects that go smoothest are the ones that didn't start against a hard deadline.
Frequently asked questions
How long does it take to build an ADU in Utah?
Plan on roughly four to six months for design, city permitting, and construction combined. Permitting timelines vary by city along the Wasatch Front, and site conditions like utility distance, grade, and rock can extend the construction phase. Projects with a locked floor plan and straightforward site access finish nearer the low end of that range.
Is a tiny home faster to build than an ADU?
Usually, yes. Tiny homes are built in our Lehi shop, so weather, site access, and travel between job sites don't slow the crew down, and site prep can happen at the same time as the build. An on-site ADU adds foundation work, utility connections, and staged inspections, which is where most extra time shows up.
How long does permitting take for an ADU?
It depends entirely on the city. Some Utah cities review plans quickly; others take longer or return comments that require revisions and a second submittal. We start the conversation with the planning counter early rather than after drawings are done, so review comments arrive while there's still time to absorb them without pushing the whole schedule.
What can I do to keep my build on schedule?
Decide your layout before permitting, choose finishes early rather than mid-build, and get clear on where the unit sits on your lot. Confirm access for delivery or equipment. If your project needs a utility upgrade, find that out at the start. Late floor plan changes are the most common self-inflicted delay we see.
Can I live on site while an ADU is being built?
Most homeowners do. Work happens outside your existing home, though there will be noise, equipment, and periods when a driveway or part of the yard is occupied. Utility tie-ins may cause short interruptions to water or power, and we schedule those in advance so you can plan around them.
If you're mapping out a timeline, come walk the model homes in Lehi, and we'll talk through what four to six months would actually look like on your property. See our homes at mycocoonhomes.com.