Bluffdale ADU Builders: Costs, Rules, and What to Check Before You Hire
Bluffdale allows two kinds of accessory dwelling units (ADUs): an internal ADU inside your existing home (like a basement apartment) and a detached ADU built as a separate structure in your yard. The city permits one per lot, requires an owner to live on site, limits a detached unit to 50% of your home's size, and allows long-term rentals only (30+ days — no Airbnb). Which Bluffdale ADU builder you need depends on which type your lot and zone support, and the most expensive mistake is designing around the wrong path.
Best for
Bluffdale homeowners with a qualifying single-family lot who want family housing or long-term rental income and are getting ready to compare builders.
Not for
Anyone counting on short-term/Airbnb income, a tiny home on wheels, or a unit they won't live near (owner-occupancy applies).
Last verified: June 2026
How this page was built — and what we are not
Utah ADU Builders is a Utah-focused ADU planning, feasibility, and builder-matching resource. We are not the City of Bluffdale, a permit authority, a lender, an architect, an engineer, or a licensed contractor. We may receive compensation when homeowners request a feasibility review or are connected with local professionals, including partner builders such as Nest Tiny Homes. That compensation does not change how we explain Bluffdale's rules, costs, or risks. We describe what the city code says, what builders typically price, and what homeowners should verify — we don't guarantee approval, pricing, or availability.
✅ What we verified for this page
- Bluffdale's ADU rules — City Code definitions (BCC 11.20.020) and standards (BCC 11.340) via the city's official ADU FAQ, Land Use pages, and ADU Toolkit. [1][2]
- Utah state law — the internal-ADU statute now at Utah Code § 10-21-303 (formerly § 10-9a-530), which makes internal ADUs a permitted use in most residential zones, exempts internal-ADU construction from impact fees, and leaves detached ADUs to local control. [3]
- Cost ranges — reviewed June 2026 and triangulated from multiple current Utah ADU cost sources. Published as planning estimates, not quotes, and excluding land.
- Fees and financing — city fees and local programs change often; we describe categories and direct you to confirm current specifics.
- Builder details — we confirmed our partner builds foundation-based ADUs (the type Bluffdale's detached rules require). We don't publish builder "rankings," reviews, or project claims we can't substantiate.
Bluffdale ADU rules that matter before you call builders
A builder quote is only useful once you know what Bluffdale actually allows. These rules decide your build path, your costs, and sometimes whether the project is possible at all.
| Question | Bluffdale answer | Why it matters before quotes |
|---|---|---|
| Are ADUs allowed? | Yes — both internal and detached ADUs are permitted in residential, mixed-use, and special-district zones. | Converting existing space and building a new structure are completely different jobs. |
| How many can I have? | One ADU of any type per qualifying lot. | Don't design around two units or an internal and detached unit. |
| Can it be an Airbnb? | No. ADU occupancy must be 30+ days (long-term). | This changes rental-income math and ROI. |
| Parking required? | +1 off-street space for an internal ADU; +2 for a detached ADU — in addition to the 2 for the main home. | Parking can decide feasibility before any floor plan. |
| Owner-occupancy? | Required — the owner must live in the home or the ADU. | Affects rental plans, resale, and who can build. |
| Max size? | A detached unit is capped at 50% of the main home; an internal unit isn't capped that way under state law (confirm with the city). | Determines how large your unit can be — and it differs by type. |
| Lot size (internal ADU)? | Parcel must be larger than 6,000 sq ft. | A smaller lot may rule out an internal ADU. |
| Tiny home on wheels? | Not allowed as a detached ADU — it must be a permanent, foundation-anchored structure. | Prevents a very common (and expensive) misunderstanding. |
| Permits required? | Yes — city approval plus building permits and inspections. | A quote that ignores permitting isn't a real quote. |
Summarized from Bluffdale City Code 11.20.020 and 11.340. Rules change — confirm the current code before you build. [1]
Free feasibility check. We may be compensated if you're later connected with a builder — see disclosure above.
Can you build an ADU in Bluffdale?
Yes. An ADU (accessory dwelling unit) is a second, smaller home on the same lot as your main house. Bluffdale allows both internal and detached ADUs on qualifying properties — but the real answer depends on your zone, lot, ADU type, parking, owner-occupancy, and permit approval. A basement conversion and a backyard cottage are not reviewed the same way, so step one is figuring out which path fits your property.
Internal ADUs (basement and in-home units)
An internal ADU is created inside the footprint of your existing home — most often a basement or lower-level apartment, sometimes called a "mother-in-law" or "granny" unit. It has its own kitchen, bath, and sleeping space. In Bluffdale, internal ADUs are allowed on parcels larger than 6,000 square feet and require one extra off-street parking space. This type is also the one most protected by state law: internal accessory dwelling units, those built inside an existing home on a qualifying lot, are a permitted use under Utah Code § 10-21-303, meaning Bluffdale can't require a conditional-use hearing or discretionary approval to let you build one. The city can still set standards around parking, occupancy, and rentals — but it can't simply say no. [3]
Detached ADUs (backyard cottages)
A detached ADU is a separate structure in your yard on its own permanent foundation. It offers the most privacy and separation — and, depending on your local market, can command higher rent than a small internal unit. It's what most people picture when they imagine a "backyard ADU," and it also carries the most rules: a detached ADU shall comply with the same setbacks for an accessory building in the zoning district, plus height limits, the 50% size cap, two extra parking spaces, and a permanent foundation. Detached ADUs are not covered by the statewide internal-ADU permitted-use statute — as of June 2026, detached units remain under local control, and Bluffdale's BCC 11.340 governs them. [1]
One ADU per lot — and not a short-term rental
Two rules trip people up. First, Bluffdale allows one ADU of any type per qualifying lot — you can't stack an internal and a detached unit. Second, Bluffdale ADUs are long-term housing: ADUs are not allowed to be used as short-term rentals and require occupancy of 30 days or greater. [1] If your plan depends on nightly Airbnb income, an ADU in Bluffdale is the wrong vehicle.
Bluffdale ADU rules at a glance (City Code 11.340)
Bluffdale's ADU standards live in City Code 11.340. The rules below change projects most often, so price your build around them — not around a generic ADU brochure.
| Rule | Internal ADU (I-ADU) | Detached ADU (D-ADU) |
|---|---|---|
| Allowed in | Residential, mixed-use, special-district zones | Same |
| Lot requirement | Parcel > 6,000 sq ft | Lot with no more than one single-family home |
| Units per lot | One ADU of any type | One ADU of any type |
| Owner-occupancy | Required (live in home or ADU) | Required (live in home or ADU) |
| Max size | Utah law limits city size caps for internal units (confirm with city) | ≤ 50% of main home |
| Short-term rental | Not allowed (30+ days) | Not allowed (30+ days) |
| Separate utility meter | Not allowed | Not allowed |
| Extra parking | +1 off-street space | +2 off-street spaces |
| Setbacks / height | Within existing home | Accessory-building standards for your zone |
| Foundation | N/A (inside home) | Permanent foundation; no wheels/trailers |
| Decks | — | No rooftop or second-story decks |
| Entrance | Existing entrance, or side/rear (non-corner lots) | Faces alley, street, rear/side façade, or rear yard |
Summarized from Bluffdale City Code 11.20.020 and 11.340. [1]
Which ADU type should you price first?
Most homeowners should price the lowest-friction legal path first. If you already have usable basement space, an internal conversion is usually simpler and cheaper than a ground-up build. A detached unit gives more privacy and flexibility (and often higher rent, depending on your local market) but adds foundation, utility, parking, and setback complexity.
| ADU path | Best fit | Bluffdale friction to check | Notes |
|---|---|---|---|
| Basement / internal | A usable lower level + lot > 6,000 sq ft | Egress windows, fire separation, +1 parking, owner-occupancy | Often the cheapest path and the first to price |
| Attached addition | Need more space, not a separate unit | Setbacks, structural tie-in, utilities, permits | Avoids some detached site constraints |
| Garage conversion | A garage you don't need for parking | Replacing required parking, fire separation, utilities, structure condition | "Cheap" only if the structure and utilities cooperate |
| Detached backyard ADU | Privacy, family housing, long-term rental | 50% size cap, setbacks, height, +2 parking, foundation, utility runs | Needs the most feasibility work before quotes |
| Prefab / modular (on foundation) | A more standardized detached unit | Must sit on a permanent foundation, be permitted, and have site/transport access | Only viable if it meets Bluffdale's detached-ADU rules (no wheels) |
When an internal ADU is the practical first estimate
If your home already has basement or lower-level space with decent ceiling height, an internal ADU is usually the fastest, lowest-cost path. It still needs permits, code compliance (egress, fire separation), parking, and owner-occupancy — but you skip a new foundation and most sitework.
When a detached ADU makes more sense
A detached ADU is the better fit when you want a fully separate unit for a parent, an adult child, or a long-term tenant — and your lot has room. Just go in knowing it's the most site-sensitive option: setbacks, height, two parking spaces, foundation, and utility trenching all have to line up.
Where prefab and Nest Tiny Homes fit
If you're drawn to a "tiny home" or prefab unit, the key Bluffdale test is the foundation: it has to be permanent, permitted, and connected to utilities — a unit on wheels won't qualify as a detached ADU. One builder we partner with, Nest Tiny Homes, builds foundation-based (slab-on-grade) ADUs and handles design and permitting. Because those units sit on permanent foundations rather than wheels, they can fit Bluffdale's detached-ADU requirement — but partnering with Nest doesn't bypass Bluffdale's rules: the 50% size cap, setbacks, height limits, two extra parking spaces, owner-occupancy, long-term rental, and permit requirements all still apply. We disclose the partnership so you can weigh it; if you want to explore that path, start with a feasibility check.
Free feasibility check. We may be compensated if you're later connected with a builder — see disclosure above.
How much does it cost to build an ADU in Bluffdale?
Bluffdale's rules don't set your construction cost — your ADU type, existing conditions, sitework, utility upgrades, finishes, and builder scope do. The ranges below are planning estimates for Utah, not quotes; your lot can move them significantly.
| ADU type | Typical Utah cost (estimate) | What pushes it higher |
|---|---|---|
| Basement / internal conversion | ~$50,000–$120,000 | Egress windows, ceiling height, fire separation, new kitchen/bath, utility upgrades |
| Garage conversion | ~$50,000–$150,000 | Structural fixes, replacing lost parking, insulation, slab/utility work |
| Attached addition | ~$150,000–$250,000 | New foundation, roof tie-in, engineering, utility work |
| Detached new build | ~$200,000–$400,000+ | Foundation, trenching, water/sewer/gas/electric, site access, finish level |
Ranges are planning estimates reviewed June 2026 — drawn from current Utah ADU cost data and our own estimating approach, and excluding land.
As a rule of thumb, Utah ADUs run roughly $190–$350 per square foot, with Salt Lake City projects often trending higher once sitework and fees are factored in. Smaller units cost more per square foot because the fixed costs (foundation, hookups, kitchen, bath) don't shrink. For a deeper breakdown, see our Utah ADU cost guide.
City fees are real — but they're a small slice of the budget
Beyond construction, expect design, plan-review, building-permit, and inspection fees. An impact fee is a one-time city charge that helps offset a new unit's demand on public services — and under Utah state law, building an internal ADU is not subject to impact fees. [3] A detached new build can involve impact fees and utility-connection costs, which vary by project. Exact amounts change over time, so confirm them for your parcel rather than budgeting from a number you saw online. The bigger cost variables are construction, sitework, utilities, and code compliance.
Why detached ADUs are hard to estimate from a "per square foot" number
A detached ADU is essentially a small house: its own foundation, trenching, utility hookups (the connections that bring water, sewer, gas, and electricity to the unit), exterior envelope, and full code compliance. A flat per-square-foot figure can hide major site-specific costs — which is exactly why a feasibility review beats a quick quote.
How long does a Bluffdale ADU take?
Plan for roughly 6 to 10 months end to end. As a typical breakdown, that's 2–3 months for design and city permitting, followed by 4–7 months of actual construction. Conversions can move faster than ground-up detached builds, and winter foundation work along the Wasatch Front can add delay. These ranges reflect typical recent Utah ADU projects; treat any timeline as an estimate, not a promise — permit review and weather are outside your builder's full control.
What can stop or reshape a builder quote?
The biggest quote-changing issues in Bluffdale are parking, size, setbacks, owner-occupancy, utility capacity, foundation, and the short-term-rental limit. Use this readiness scorecard to spot problems before you compare bids.
| Factor | 🟢 Green light | 🟡 Yellow flag | 🔴 Red flag |
|---|---|---|---|
| ADU type | You know which type you want | Comparing a few types | Asking builders to quote with no chosen path |
| Parking | You can show required off-street parking | Parking may need a redesign | Required parking looks impossible |
| Rental use | Long-term or family use | Lease/use plan unclear | Short-term/Airbnb plan |
| Owner-occupancy | Owner will live in home or ADU | A future move/sale is likely | You can't meet owner-occupancy |
| Detached size | Unit fits the 50% cap and lot | Size may need trimming | Unit exceeds limits |
| Foundation | Permanent-foundation path is clear | Prefab/modular details unclear | Wheels/portable structure only |
| Utilities | Utility route/capacity can be evaluated | Upgrades likely | No realistic utility path |
| Permit packet | Site plan/floor plan/elevations can be prepared | Missing details | No plan for city review |
Two of these deserve emphasis. Owner-occupancy affects not just your rental plans but resale — the requirement follows the property, so a future buyer has to be willing to live on site too. And the short-term-rental ban is the single most important reality check for anyone running Airbnb math: in Bluffdale, ADUs are for 30-day-plus stays, full stop.
What permits and documents do Bluffdale ADU builders need?
Bluffdale requires homeowners to obtain city approval and building permits before an ADU is used, with inspections during construction. A productive builder conversation usually needs a clear ADU type, a site plan, floor plans, elevations, a parking layout, and answers to your utility questions.
A simple way to think about the path:
- Before design: nail down ADU type, lot/zoning fit, parking, owner-occupancy, intended use, and utility route.
- Before application: prepare a site plan (showing parking), floor plans, and elevations.
- Before use: secure approval, pass inspections, and meet occupancy rules.
For a new dwelling unit, the building permit is generally pulled by a licensed contractor rather than the homeowner — confirm with your builder who handles permits and inspections. (This is general practice, not legal advice; your project's requirements should be verified.)
How do you choose a Bluffdale ADU builder without getting bad quotes?
The best first question isn't "who's cheapest?" — it's whether the builder can price the actual Bluffdale path you're likely to build, including parking, utilities, foundation, code compliance, and permits. A bid that skips those isn't comparable to one that includes them.
Ask before you request a quote
- Have you built or priced ADUs under Utah city-specific rules?
- Do you handle internal, attached, garage, and detached/prefab units — or just one type?
- What's included in the estimate (design, engineering, permits, sitework, utility trenching, foundation, finishes)?
- What's excluded?
- How do you meet Bluffdale's parking requirement?
- How do you evaluate utility capacity and upgrade risk?
- Who prepares site plans, floor plans, and elevations?
- Who coordinates permit submissions and inspections?
- What assumptions could change the price later?
- What timeline is realistic after permit review?
A useful Bluffdale ADU estimate should spell out:
ADU type and square footage; scope inclusions and exclusions; design/engineering assumptions; sitework and foundation assumptions; utility assumptions; permit/inspection assumptions; finish level; a contingency for unknowns; and a realistic timeline.
Our practical view: don't jump straight to "quotes" before you understand basic feasibility. Identifying your likely ADU type, property constraints, and cost range first makes every bid easier to compare — and protects you from sinking money into plans for a project your lot can't support.
Free feasibility check. We may be compensated if you're later connected with a builder — see disclosure above.
Is there financing or assistance for a Bluffdale ADU?
Most homeowners fund an ADU through standard tools — a home-equity loan or HELOC, a cash-out refinance, a renovation or construction loan, or builder-arranged financing. Some cities, counties, and the state of Utah also run ADU or housing-assistance programs, but these come and go, are often limited by funding and geography, and can carry conditions like deed restrictions, affordability requirements, owner-occupancy, repayment triggers, or forgiveness terms. Verify any program's current availability and terms directly before you build a plan around it. Bluffdale's ADU Toolkit, created with the Salt Lake County Housing Trust Fund, is a sensible place to check for any current local options. [2] We are not a lender and can't guarantee financing approval; see our Utah ADU financing guide for a broader overview.
Before you call builders: a Bluffdale ADU readiness checklist
You're ready for a productive builder conversation once you know your likely ADU type, rough size, parking plan, utility questions, intended use, budget range, and permit path. Without those, quotes are harder to compare and more likely to change.
Gather this first:
- Property address or parcel details
- Current home type and approximate square footage
- Desired ADU type (internal, attached, garage, detached, prefab)
- Intended use (family housing, long-term rental, office/guest space)
- Whether you can meet owner-occupancy
- A parking plan for the extra required space(s)
- Photos of your basement, garage, or backyard
- Utility questions (electrical panel, sewer, gas)
- A rough budget range
- A desired timeline
- Any HOA or private covenant (CC&R) concerns to verify
- Whether your plan depends on short-term rental income (in Bluffdale, it can't)
Free feasibility check. We may be compensated if you're later connected with a builder — see disclosure above.
Honest take: is a Bluffdale ADU worth it?
An ADU is not automatically a smart project just because Utah and Bluffdale have become more ADU-friendly. The right project depends on your lot, your zone, your utilities, your budget, and your use case. If you were counting on Airbnb income, planning a tiny home on wheels, unwilling or unable to live on site, working with a lot at or under 6,000 square feet for an internal unit, or facing tight setbacks for a detached unit, the numbers may not work — and it's far cheaper to learn that before you pay for plans or chase quotes. That's the entire point of starting with a feasibility review: confirm the constraints for your specific parcel, then decide with clear eyes.
Bluffdale ADU builders: FAQ
Ready to check the rules, realistic cost, and build path for your Bluffdale property?
Request a Bluffdale ADU feasibility review →Sources we checked
Concept and educational images on this page are illustrations only; actual design, cost, and approval depend on your site and Bluffdale's current rules.
- City of Bluffdale — ADU FAQ and standards (BCC 11.20.020 and 11.340):
https://www.bluffdale.gov/faq.aspx?TID=28 and https://www.bluffdale.gov/271/Land-Use-Ordinances - City of Bluffdale — ADU Toolkit (developed with the Salt Lake County Housing Trust Fund):
https://bluffdale.gov/883/ADU-Toolkit - Utah Code § 10-21-303, Internal accessory dwelling units (formerly § 10-9a-530), and the Utah Property Rights Ombudsman's ADU guidance:
https://le.utah.gov/xcode/Title10/Chapter21/10-21-S303.html and https://propertyrights.utah.gov/find-the-law/legal-topics/adu/
Cost ranges reflect current Utah ADU cost data and Utah ADU Builders' own estimating approach, provided as planning estimates. Rules, fees, and programs change; we re-verify this page on a regular schedule.