Custom Home Builder Eastern Idaho: Fixed-Price After Design Agreement, Across Bonneville, Madison, Jefferson, Bingham, Fremont, and Teton Valley

I’m Bryce Swager. I build custom homes in eastern Idaho and Teton Valley, and I serve Jackson-side clients from the Idaho side. Fourth generation out of Rigby, first-generation builder with 20 years in construction. I’m registered in Idaho, and my BuildZoom score is 94. If you’re looking for a builder who prices your project only after a signed design agreement, holds that price after construction contracts sign, and knows the county fee schedules by heart, keep reading.

SwagerBuilds LLC is a 20-year custom home builder and general contractor from a 4th-generation Rigby entrepreneur family, based in Rigby, Idaho, serving Eastern Idaho and Teton Valley. Owned and operated by Bryce Swager, SwagerBuilds is registered in Idaho, holds a BuildZoom score of 94, and every project — new construction, whole-home remodel, or addition — is delivered under a written fixed-price contract with zero surprise allowances. Call (208) 520-0636.

This page covers who I serve, how I price, what the permit landscape actually looks like on this side of the state, and the timeline you should plan around. If you want to skip to a conversation, my number is (208) 520-0636.

Who I Am and Where I Build

My family has been building businesses in the Snake River Plain for four generations, and I’m the first-generation builder in the family, with 20 years in construction. I run SwagerBuilds out of Rigby and take on custom homes, remodels, and shops across six Idaho counties:

• Bonneville County (Idaho Falls, Ammon, Iona, Ucon, Swan Valley)
• Jefferson County (Rigby, Menan, Lewisville, Roberts)
• Madison County (Rexburg, Sugar City)
• Bingham County (Blackfoot, Shelley, Firth)
• Fremont County (Island Park, Ashton, St. Anthony)
• Teton County ID — Teton Valley (Driggs, Victor, Tetonia)
• Jackson-side clients served from the Idaho side (Jackson Hole, Teton Village, Alta, Wilson)

That footprint isn’t a marketing radius. It’s the counties where I already know the plans examiners, the septic inspectors, the trades, and the fee schedules. I say no to work outside it because a builder who doesn’t know the local process is a builder who’s going to be slow and expensive on your job.

How Fixed-Price After Design Agreement Works

Most custom home contracts in eastern Idaho are cost-plus. Allowances for cabinets, allowances for flooring, allowances for lighting, an open line item for “unforeseen.” The final number comes in whatever it comes in at, and you find out at the end.

SwagerBuilds doesn’t work that way — but we also don’t hand out fixed-price bids on custom projects before design is done, because nobody honest can. Instead, we work through a signed design agreement. During that phase (typically 12–16 weeks), we lock the plan, spec every finish, get real bids from real subs, and hand you a fixed construction contract price. If we miss something during that phase, that’s on us. If a sub raises their number after we’ve signed the construction contract, that’s on us. The only line items that can move the price are documented change orders you initiate.

Why bother? Because the alternative punishes the homeowner. NAHB’s 2024 Cost of Constructing a Home study reports that construction costs account for 64.4% of the average new home price, with interior finishes alone eating 24.1% of construction cost. Those are the line items cost-plus builders leave loose. A signed design agreement forces us to bid finishes for real before you sign the construction contract — which is the only way you actually know what your house costs.

2026 Construction Cost Across the Region

Homes run $400 per square foot and up — construction cost, on interior living space. How far up it goes depends on the finishes and fixtures you choose, and that’s your call to make. Once the design and selections are set, your price is fixed.

That’s the same range whether you’re on a serviced Rigby city lot or a hillside above Wilson. What moves your project above the starting point is what you’re actually building and where:

• Finish level. Production-grade cabinetry and tile versus custom millwork is the single biggest lever. NAHB puts interior finishes at 24.1% of construction cost — that’s the line item that moves most.
• Site complexity. City sewer and water on a flat lot is a different number than acreage with a well, septic, engineered driveway, and 400 feet of utility trench.
• Structural spans and design. Open spans, vaulted ceilings, walkout foundations, and heavy timber all carry engineering and framing cost that a simple rectangle doesn’t.
• Envelope and snow load. Climate Zone 7/8 assemblies and 100+ psf snow loads cost real money in foundations, framing, and insulation that valley-floor builds don’t carry.

All-in project cost (land improvements, soft costs, design fee, contingency, financing carry) typically adds about 30% on top of construction cost.

What drives cost across the region

Area	What drives your number here
Bonneville County (Idaho Falls, Ammon)	City infrastructure available; standard site work; finish level is the main lever
Jefferson County (Rigby, Menan)	County-served permits; well and septic common on acreage parcels
Madison County (Rexburg)	10 working day plan review minimum; MEP permits run through City of Rexburg
Bingham County (Blackfoot, Shelley)	Longer trade drives push subcontractor pricing up
Fremont County (Island Park, Ashton)	6,200+ ft elevation, 100+ psf snow load, May–October site work window, remote logistics
Teton Valley ID (Driggs, Victor, Tetonia)	Higher energy code, 70+ psf snow load, mountain logistics, Teton Valley labor premium, haul time from Idaho Falls suppliers
Teton County WY (Jackson, Wilson, Teton Village)	Energy Mitigation fees on homes over 2,500 SF, LDR review, remote site logistics, tight labor pool, 2024 IRC baseline

For context on what’s driving cost nationally: NAHB’s 2024 breakdown puts framing at 16.6%, major system rough-ins at 19.2%, and interior finishes at 24.1% of construction cost. Site work adds 7.6%. Foundations 10.5%. Eastern Idaho tracks close to those national ratios on standard valley builds; Teton Valley, Fremont County, and Jackson skew heavier on foundations (frost depth, seismic), envelope (energy code), and site work (mountain access, seasonal windows).

If you want a project-specific number, run the custom home cost calculator or the remodel calculator. For a deeper Teton Valley breakdown, see my 2026 Teton Valley custom home line-item breakdown. For Bonneville County specifically, see my Bonneville County cost page.

The Permit Landscape, Plainly

Idaho doesn’t have one permit process. Every county and city runs its own. Some counties handle building for their small cities; some don’t. Here’s the shape of it across my service area.

Bonneville County + Idaho Falls + Ammon

The Bonneville County Building Inspection office handles unincorporated county residential permits at 208-524-7920. The county doesn’t publish an inline residential fee table — you get a project-specific fee estimate over the phone or by pulling the fee PDFs from the Building Permit & Zoning Fees page.

Inside Idaho Falls city limits, the Community Development Services / Building Division publishes the current 2025–2026 Fee Schedule as a PDF, alongside its Permit Processing page with residential submittal checklists. Building Division contact: 308 Constitution Way, 208-612-8100.

Ammon runs its own building department at 2135 South Ammon Road (208-612-4000). Submissions go through the BluePrince portal. The Ammon Building Permits page lists review time as 5–10 business days. Current fees are set by Fee Resolution Amendment 2025-002 (Spring 2025).

Jefferson County + Rigby

Jefferson County’s Planning, Zoning & Building Department handles building permits for the cities of Lewisville, Menan, and Rigby — those small cities don’t do their own plans review. The City of Rigby issues its own zoning permits for decks, fences, garages, sheds, sidewalks, signs, and solar, but structural review flows through the county.

If you’re building a shop in Jefferson County, I wrote a step-by-step: Do I need a permit to build a shop in Jefferson County?

Madison County + Rexburg

Madison County adopted the 2018 I-Codes (IBC, IRC, IMC, IECC, IFGC, IEBC, IFC) plus the 2017 Idaho State Plumbing Code and 2017 NEC. Their building permit page is explicit: “the review process will require a minimum of ten (10) working days.” Non-accessory structures pay a non-refundable $500 submittal deposit that credits toward the permit fee. Accessory structures pay 10% up front, non-refundable.

MEP permits for county jobs run through the City of Rexburg building department, not the state. That’s a common surprise for owners who assumed the state handled trade permits.

Bingham County

Bingham County Planning & Development sits at 490 N Maple, Suite A, Blackfoot (208-782-3177). They also run the 2018 I-Codes, submit through ViewPoint Cloud, and adopted a new fee schedule under Resolution 2026-17, effective 3/6/2026.

Fremont County + Island Park

Fremont County handles building permits out of St. Anthony for the unincorporated county — which includes the Island Park area, one of the most demanding build environments in eastern Idaho. Elevation regularly clears 6,200 feet, ground snow loads run 100+ psf in most of the Island Park caldera, and the seasonal build window is short (typically May through October for site work). Well and septic are the norm on rural parcels, and Eastern Idaho Public Health handles septic permitting. Contact Fremont County Planning & Building at 208-624-7332 for project-specific fee and process detail.

Teton Valley (ID) and Teton County (WY)

The Teton County ID Building Department uses the 2018 I-Codes and publishes an Excel fee estimator for residential work. One quirk: personal checks over $5,000 aren’t accepted — anything above that is certified check.

Teton County WY is a different animal. Permit fees are calculated off ICC Building Valuation Data times a tiered multiplier per the 2026 Fee Schedule. On top of the standard permit and 65% plan review fee, homes over 2,500 SF trigger the Energy Mitigation Program — $4/SF between 2,501–5,000 SF and $8/SF above 5,000 SF (with credits for PV, super-insulated envelopes, and passive design). Since 2/1/2025, the county operates under the 2024 IRC and IBC. That’s the current baseline any Jackson-side custom home has to design against.

For a deeper permit breakdown by county, see my Idaho building permits by county pillar.

Timeline Realities

Owners often ask how long a custom home takes here. The honest answer depends heavily on where you’re building. Plan review alone runs from about a week in the city offices to 10 working days minimum in Madison County. Then you’re in the queue for inspections and dependent on trade availability.

• Design agreement phase (design + engineering + finish spec): 12–16 weeks depending on complexity
• Plan review + permit issuance: 1–4 weeks in Bonneville/Ammon; 2–4 weeks in Madison; 6–12 weeks in Teton County WY when LDR review is involved
• Site work + foundation: 3–6 weeks (frost, weather, and soils dependent)
• Framing through dry-in: 6–10 weeks
• MEP rough-in and inspections: 4–8 weeks
• Finishes + punch: 10–16 weeks

Total: roughly 8–14 months for a typical eastern Idaho custom home from signed construction contract to closeout. Teton Valley, Fremont County, and Jackson jobs run longer — 12–20 months isn’t uncommon once you factor mountain logistics, seasonal build windows, and mandatory review windows.

Idaho has been running near the top of the country for new-home authorization for years. Per Construction Coverage’s 2025 analysis of Census Building Permits Survey data, Idaho leads the nation with 21.2 new units authorized per 1,000 existing homes — more than twice the national average. Trade demand is real, and it’s why calendar slots fill up fast. Reserving a build slot through a design agreement is often the practical way to secure a start date.

Design Criteria You Should Know Before Drawing Plans

Idaho and Wyoming use the same base code families but the local climatic and geographic criteria change everything about what the house has to do. A few load-bearing numbers:

• Bonneville County ground snow load: The ASCE 7 tool returns “Site Specific Location: Case Study Required” for Bonneville County. There’s no single county-wide value — you need an engineered analysis for your specific site.
• Fremont County / Island Park: Ground snow loads of 100+ psf in most of the caldera, elevation 6,200+ ft, seasonal build windows May–October for site work.
• Teton County WY design criteria: Wind 105 mph, Seismic Design Category D, frost depth 34 inches, winter design temperature -30°F, Climate Zone 7/8 requiring R-60 ceilings and R-20+5 walls per the county Design Criteria page.
• Idaho statewide baseline: The Idaho Division of Building Safety adopts the 2018 IBC and IRC (Idaho Residential Code 2020 Edition), 2018 IECC, 2023 NEC, and 2017 Idaho State Plumbing Code per the 2025 DBS adopted codes list.

Those criteria drive foundation depth, envelope insulation, structural sheathing, and shear detailing. If your designer isn’t building them in from the first sketch, you’re going to eat change orders during framing.

How I Run Jobs

My process page covers this in more detail, but the short version:

• Free 45-minute discovery call to figure out fit
• Signed design agreement (paid): during this phase we lock plan, spec every finish, get real subcontractor pricing, and hand you a fixed construction contract price
• Fixed construction contract after design is locked and finishes are specified
• Weekly on-site owner walks with schedule + spend update
• Documented change orders — never verbal, never after-the-fact

You can see finished work in the portfolio, common questions in the FAQ, and past client feedback in reviews. I also keep a page on cost reality so you can see the math I use.

What I Build

• Custom homes — 1,800 to 6,500 SF, single family, primary residence or second home
• Whole-house remodels and additions in existing homes
• Shops and outbuildings — RV storage, hobby shops, agricultural

I don’t do speculative subdivisions or tract builds. Every job is a one-off for a specific owner on a specific lot, priced only after a signed design agreement.

Trade Base and Why It Matters

A custom home is the sum of maybe 25 to 40 subcontractor relationships. Excavation, foundation, framing, roofing, siding, windows, HVAC, plumbing, electrical, insulation, drywall, paint, cabinets, countertops, tile, flooring, low voltage, garage doors, appliances, landscape, driveway. Every one of those trades has to show up on the right day with the right materials for the schedule to work.

My trade base is local. Framers out of Rigby and Idaho Falls, HVAC and plumbing that runs the eastern Idaho corridor, cabinet shops in the region, and Wyoming-side trades for Teton County WY work when the drive from Idaho pushes an eastern Idaho sub off the job. Local relationships mean I can call and get a straight answer on lead times before I quote your job — not after we’ve signed and you’re waiting on a truss package that quoted 6 weeks and shipped in 14.

Concrete work — foundations, flatwork, thickened-edge footings on shop builds — goes to Skinner Custom Concrete in Rigby. They’ve been on the roster long enough that I trust their pours and their schedule without having to babysit either.

Plumbing referrals for service work — water heaters, repairs, softeners — run through two builder-vetted channels depending on where the house is. On the valley floor it’s Eastern Idaho Plumbing Pros in Idaho Falls. In the mountains it’s Teton Valley Plumber, covering Driggs, Victor, Tetonia, Alta and the Jackson side — the same plumber I use on my own Teton Valley jobs for frozen pipes and second-home winterization. Same vetting standard as everything else on this roster: licensed, inspected on real jobs, and they show up.

NAHB’s 2024 data puts overhead and general expenses at 5.7% of the sales price — that includes the office, the scheduling, and the project management that keeps 30+ trades sequenced. Owner-built and price-shopped jobs skip that line item and pay it back in schedule slip and rework.

Common Questions I Get at the First Call

Do you build on my lot or your lots? Your lot. I don’t develop or sell finished homes. If you don’t have a lot yet, I can point you at the questions to ask before you buy.

Do you take small remodels? Selectively. Kitchen and bath remodels in the $75k+ range and whole-house remodels — yes. Small handyman work — no.

Why won’t you give me a fixed-price bid before design? Because nobody honest can. A fixed-price bid before design is done is either an allowance-heavy contract wearing a fixed-price label, or it’s a number that’s going to walk 15–25% by move-in through change orders. The design agreement is what makes the fixed construction contract that follows it actually hold.

How much design should I have before I call? Anything from a Pinterest board to fully permitted plans. If you’re still early, I’d rather look at floor plans before they’re engineered — that’s when small changes are cheap.

Shopping the Idaho Falls side specifically? I put together an honest comparison of custom home builders in Idaho Falls, including the ones I compete with.

Start a Conversation

If you have a lot, a set of plans, or just an idea you’re kicking around, the fastest way to get a real answer is to fill out the intake form. It takes about four minutes and gives me enough to tell you whether I’m the right builder for your project before we spend an hour on the phone.

Or call me directly: (208) 520-0636. Or use the contact page.

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About the Author

Bryce Swager, Founder — 20-year Rigby custom home builder. BuildZoom score 94. Idaho Contractor Registration RCE-57499. Direct: (208) 520-0636. More about Bryce.

Idaho Contractor Registration RCE-57499

Hiring for the contractual role rather than the house itself? Our general contractor page for Teton Valley covers what a GC is actually on the hook for, what Idaho registration does and does not prove, and how to vet a bidder.