The short answer
A custom home in Madison County is priced the same way as one in Idaho Falls. Guardian estimates every home in the Idaho Falls–Rexburg valley on the same per-square-foot basis. Only Teton Valley and Park City get a location adjustment. In Madison County, the lot and the permit schedule are what move your number.
Real line items from a recent Rexburg build
These are actual costs from one Guardian custom home in Rexburg. They are not a quote, but they show where the money goes before the framing starts:
| Line item | Actual |
|---|---|
| Building permit (Rexburg) | $3,901 |
| Lot fill and grading | $20,675 |
| Excavation and utility trenching | about $8,000 |
| Well hookup | $17,335 |
Fill is the one people don’t see coming. On a lot that sits low, bringing it up to grade can cost more than the excavation.
Permits and plan review
- Permit cost. Guardian budgets $3,000–$5,000 for a building permit on a subdivision lot and $4,000–$7,000 on a rural parcel.
- Plan review. Expect 3–6 weeks in a normal season. Summer can push it to 8–10 weeks, because growth around Rexburg and Sugar City fills the queue. Submit before you need to.
- Code. Madison County builds to the International Residential Code with local amendments. See Idaho building permits by county for what every county asks for.
Well and septic on rural parcels
Outside city services you’re drilling a well and installing a septic system, and both are permitted before the build starts. We broke out the costs and the Eastern Idaho Public Health timeline in well and septic costs in Madison County.
What’s priced separately
Guardian quotes the house and the land separately. These are also their own line items, outside the per-square-foot number:
- Sloped lots and retaining walls
- Long driveways
- Rural well drilling
- Garages over 1,000 sq ft and covered porches over 400 sq ft
How long it takes
Twelve to fourteen months from foundation to final walkthrough is typical. Allow extra time for summer plan review in Rexburg. Here’s how the months break down.