Basement to Legal ADU: What It Really Takes

• Turning an unfinished basement into a legal ADU costs more than standard basement finishing, because it must work as a legally independent, rent-generating home.
• A 1,500 square foot unfinished basement takes 4 to 8 weeks to finish normally, but the same footprint as a legal ADU runs 8 to 12 weeks.
• The extra month is not from more drywall — it comes from complying with Provo City Code 14.30 and establishing legal separation.
• To safely sleep downstairs you need a guaranteed emergency escape route, so builders cut through the concrete foundation to install an egress window.
• Coordinating these structural safety additions and securing the mandatory city permits is what officially makes the space a legally recognized residence.

Lehi Backyard Cottages: What the Rules Allow

• Detached backyard cottages (ADUs) are strictly prohibited in Lehi's designated "planned community" zones — no exceptions.
• You cannot run a short-term rental like an Airbnb or VRBO and have an active ADU on the same single-family lot; only one of those uses at a time.
• Finishing your basement into an internal apartment needs a 6,000 square foot lot, but a detached stand-alone cottage requires a 14,520 square foot lot.
• A property slope over 20% rules out a detached ADU entirely; a slope between 10% and 20% means submitting an official engineered grading plan.
• A backyard cottage is capped at 1,300 square feet of finished living area and must be built on a permanent foundation, not a shed or tiny home on wheels.
• A minimum five foot setback from the property line is generally required, and Lehi's "half-address suffix rule" gives the cottage a fractional address (123 Main Street becomes 123 and a half Main Street) so emergency crews know it is detached.
• Converting an existing structure built before January 1st, 2021 triggers a conditional use permit, and the dwelling portion must be at least 300 square feet.
• The code mandates a 12 foot wide all-weather access path plus two dedicated 9 by 20 foot off-street parking stalls for the ADU, on top of the primary home's parking.
• All utility lines — water, sewer, power — must tie directly back into the primary house; separate city hookups are not allowed, and a one-time municipal impact fee is required before the building permit is issued.

Utah HVAC Rebates: What You Need to Know

• A qualifying dual fuel heat pump system unlocks a combined $2,450 in utility rebates for many Utah homeowners, and it is direct cashback from the utilities, not a tax deduction that takes a year.
• Rocky Mountain Power offers $1,450 for the electric heat pump side through its Watsmart program, and Dominion Energy Utah adds $1,000 for the high-efficiency gas furnace backup.
• Utah's electric and gas utilities have aligned their efficiency requirements, which is what lets you stack both rebates on a single-home system.
• You have exactly 180 days from installation day to submit the online application; miss it, and the rebates are permanently forfeited with no grace period and no appeals process.
• The system must be installed by a registered Watsmart trade ally — a non-registered installer gets the application rejected no matter how efficient the equipment is.
• You must demand an AHRI certificate with a specific match number proving the paired units hit the exact CR2 and HSPF2 efficiency ratings the utility requires.
• Standard heat pumps might need a 15.2 CR2 rating, while heavy-duty cold climate units need 17.
• A standard new HVAC system earns $0 in rebates — you have to actively buy an AHRI match dual-fuel system that hits the utility tiers.
• The top tier cold climate heat pump rebate also requires equipment listed on the NEP (Northeast Energy Efficiency Partnerships) Qualified Products list.
• Three-step path: hire a registered Watsmart trade ally, get your AHRI certificate before paying the final invoice, and submit the complete application inside the 180-day window.

Short Clip 78S

• Closed cell spray foam stops winter drafts, while traditional fiberglass only filters freezing air and absorbs moisture instead of blocking it.
• A basement rim joist is the seam where the home's wooden framing meets the concrete foundation, and this structural gap is naturally porous.
• Freezing exterior wind and moisture leak right in through that gap, so a liquid chemical is sprayed directly into the cavity.
• Closed cell foam is built from microscopic bubbles that are completely sealed off from each other.
• The liquid swells to many times its original volume, forces its way around wiring and into the wood grain, then cures into dense, rigid plastic within seconds.

How Building A Basement Adu Works

• Watch this short guide on basement finishing topics that Utah County people ask about most.
• Practical, plain-language advice you can use when planning your project.

How Closed Cell Foam Seals Basements

• Watch this short guide on basement finishing topics that Utah County people ask about most.
• Practical, plain-language advice you can use when planning your project.