What is the smallest ADU that pencils financially in Driggs?

Below roughly 500 square feet, fixed costs like foundation, permit, septic tie-in, utility runs, kitchen, and bath dominate the per-square-foot number and the return on rent gets ugly. Most Driggs ADUs SwagerBuilds builds land between 600 and 900 square feet for a real one-bed one-bath. For long-term family housing, 900 to 1,200 square feet is the next step up.

Building ADUs in Driggs and the Rest of Teton Valley, Idaho

Q: Can I build the ADU before I finish the main house in Driggs?

In most Driggs and Teton County ID scenarios, yes, but it depends on zoning. Some parcels require the primary dwelling to exist before an accessory unit is permitted. Others let you build either first. Live in the ADU while building the main house is a common play, but confirm the parcel zoning up front.

Driggs has plenty of empty lots and existing homes with room for a second dwelling, but not many contractors in town will name a fixed number and hold it. If you own land inside Driggs city limits or out in unincorporated Teton County ID, an accessory dwelling unit is one of the highest-value moves you can make on the parcel. Rent it, house family, or run it short-term where the code allows. Full pricing structure and finish tiers are on the ADU Builds hub. Ready to price yours? Start here.

Start Your Driggs ADU Price

The Problem With Building an ADU in Driggs

Building an ADU in Driggs sounds simple until you start on permits. Inside city limits, Driggs allows short-term rentals under a registered permit with transient room tax collected. Cross the line into unincorporated Teton County ID and the rules shift again, with a separate STR process, different setbacks, and its own read on impact fees. That single boundary changes what your ADU is worth on day one.

Then there is the ground itself. Almost every Teton Valley parcel runs on private well and septic. A second dwelling triggers a septic design-flow evaluation, sometimes forcing an upgraded tank or a full new drainfield. Your well permit may or may not cover the extra load. Snow load on secondary structures runs high here, roughly 60 to 90 psf depending on site [VERIFY WITH BRYCE], which prices out most kit-shed conversions before framing.

The people asking me to build these are usually pricing aging-parent housing, mortgage-offset rental income, or a bunk unit for family that visits four months a year. All three math out. Only if you plan for what is actually in the dirt.

Why a 20-Year GC on a Driggs ADU

I am Bryce Swager, a fourth-generation Rigby builder running fixed-price GC work across Eastern Idaho for 20 years. SwagerBuilds runs ADU and shop jobs in Driggs, Victor, Alta, and across the pass into Jackson.

What that gets you on a Driggs ADU:

I know which subs actually show up in Teton Valley in February and which ones ghost past Halloween. On a 9 to 10-month build, that difference is your delivery date.
I have dealt with the City of Driggs building department and the Teton County ID permit office enough to know which items they flag on ADU applications and which they wave through.
Cold-weather concrete pours in this valley take a specific skill. Blankets, additives, and pour timing all matter. Get it wrong and the slab cracks before spring.
Fixed-price with no allowances means the contract number is the number. If a hidden condition shows up mid-build, it is on me to have scoped it or eat it, unless you sign a written change order.
Every job runs through JobTread. You see the daily log, the live budget, RFIs, and photo updates from your laptop wherever you live.

What This Costs

Straight talk on Driggs ADU pricing: the range depends on the ground you are building on and what you want inside the unit. A detached one-bedroom ADU with a full kitchen, one bath, and independent utility feeds typically lands in a per-square-foot range that reflects Teton Valley labor rates, snow-load engineering, and cold-climate insulation. [VERIFY WITH BRYCE — specific $/sf range to publish]

That range assumes:

No unusual dirt work, meaning no rock and no drainage remediation
Standard septic tie-in or a moderate tank expansion
Mid-range finishes, not builder-grade and not top-tier
Utility service already at or near the property line

Line items that push the number: heated slab, standing seam metal roof (worth it in Driggs), a second septic tank, a well upgrade, a covered breezeway to the main house. Every one of them is spelled out in the fixed-price contract before you sign. No allowances that balloon at month three.

Permits and Codes

Where your ADU sits on the map determines who permits it.

Inside Driggs city limits: City of Driggs building department. ADUs need to meet the city’s accessory dwelling ordinance, typically including a maximum size relative to the primary residence plus setback and lot coverage limits [VERIFY WITH BRYCE on current owner-occupancy requirement]. Short-term rental use requires registration with the city and payment of the transient room tax.

Unincorporated Teton County ID: Teton County Planning and Building. Different setbacks, and a separate short-term rental permit path with its own rules. Impact fees for water and sewer only apply where those systems exist, meaning most rural parcels shift cost to Central District Health for septic sizing.

Septic sizing: a licensed installer runs a design-flow calculation on your existing tank and field against the second dwelling load. Snow load engineering runs 60 to 90 psf on secondary structures [VERIFY WITH BRYCE].

The Fixed-Price Process

How every SwagerBuilds ADU runs: you send a rough concept and lot photos, I do a site walk, we scope it together, and I put a fixed number in a real contract before you commit. No cost-plus. No allowances that grow. If I missed something inside the scope, it is on me unless you change the scope in writing.

You get a JobTread client portal from day one. Daily photo log, live budget, RFIs, change orders, schedule. If you are not in Driggs, and most of my ADU clients are not, you can run the whole job from your desk. Read the full process writeup for how the fixed-price is structured and how change orders work when you actually change the scope.

Remote-Owner Friendly

About 60 percent of my Teton Valley clients live somewhere else. They bought land or a cabin here and want an ADU built without flying in every other week to check on the framer.

The setup: JobTread portal plus weekly video walkthroughs plus a shared folder for finish selections. Texts get answered within a workday. Selection calls run on Zoom with screen share. Deliveries and inspections run on my calendar, not yours. See Build From Anywhere for the full remote workflow and what I need from you at each phase.

Driggs ADU FAQ

Do I need a separate septic system for a detached ADU?

Usually no, but you might need to upsize your existing tank or extend the drainfield. A licensed installer runs a design-flow calculation on your existing setup against the added load, meaning bedroom count in the ADU, expected occupancy, and whether the main house has a garbage disposal. If your current system was sized tight for the main house, adding an ADU forces an upgrade. Central District Health signs off on it. I get that evaluation done during design so it is inside the fixed-price number, not a surprise at month four.

Can I rent my Driggs ADU short-term?

Inside Driggs city limits, yes. You register with the city, pay the transient room tax, and follow occupancy limits. Outside city limits in unincorporated Teton County ID, the county runs a separate short-term rental permit path with different rules. Both jurisdictions have tightened enforcement over the last few years. If STR income is core to your financial model, get the permit path confirmed in writing before you break ground. I walk through the current posture during the scoping call. [VERIFY WITH BRYCE]

What is the smallest ADU that pencils financially?

Below roughly 500 square feet, the fixed costs of a foundation, permit, septic tie-in, utility runs, kitchen, and bath start to dominate the per-square-foot number and the return on rent gets ugly. Most Driggs ADUs I build land between 600 and 900 square feet, big enough for a real one-bed, one-bath with a full kitchen and a small living area. If you are housing a family member long-term, 900 to 1,200 square feet is the next step up. Below 500 is a bunk unit, not an ADU.

How does the ADU affect my property taxes?

Teton County ID reassesses when you add a structure. Taxable value goes up by roughly the assessed value of the ADU, not the full construction cost, but close to whatever the assessor puts on it at market. If the ADU generates rental income, that is a separate income tax question for your CPA. I am not a tax professional. Talk to one before you commit.

Can I build the ADU before I finish the main house?

In most Driggs and Teton County scenarios, yes, but it depends on zoning. Some parcels require the primary dwelling to exist before an accessory unit is permitted. Others let you build either first. If you want the ADU up first and live in it while the main house is built, that is a common play. I have done it. We confirm the zoning up front so we do not get halfway through and hit a permit block. [VERIFY WITH BRYCE]

Ready to Price a Driggs ADU?

Send the concept, the address, and what you want the unit to do (rent, family housing, or both). I come back with a scope and a real number in 5 to 10 days.