The five inputs
- Living area, square feet (0–6,000) — the finished home.
- Shop area, square feet (0–8,000) — bays, garage, workshop. Finished or shell.
- Scope: Shell (posts, steel, doors and windows, no slab) · Dry-in (shell plus slab and exterior openings) · Turnkey (finished home; shop finished or shell).
- County: Franklin · Jefferson · Warren · Lincoln · St. Charles · Other — sets the permit and septic-permit allowance, and shows the county's minimums (five acres in Jefferson and St. Charles; three in Warren; St. Charles's 800-square-foot minimum dwelling).
- Site package: None (prepared site, utilities in) · Typical (septic, well, driveway and entrance, electric within Ameren's free footage, clearing and grading — $30,000–$80,000) · Extended (long driveway, line extension, difficult septic — $60,000–$120,000).
What you get
- A low-to-high total and a blended per-square-foot figure.
- The drivers: shell/dry-in/turnkey band × footprint or living area, shop band × shop area, the county's adder with its label, the site package.
- Notes that apply: the Farm Credit ten-acre rule; a tall-shop-bay adder above 1,200 square feet of shop; the St. Charles minimum-dwelling note.
- A downloadable brief (text or PDF) with your inputs and range, to attach to the quote form.
What the estimate cannot know
Your soil (which decides the septic system within the site package), the distance to power, rock in the post holes, allowance choices, custom spans or eave heights, and the county's unpublished fee tables. The written estimate after the county and site check is exact and good for 30 days.
Reference bands (2026, St. Louis ring)
| Scope | Per sq ft |
|---|---|
| Shell (footprint) | $45 – $65 |
| Dry-in with slab (footprint) | $60 – $85 |
| Turnkey living area | $160 – $230 |
| Finished shop area | $55 – $80 |
| Shop as shell | $45 – $65 |
| Tall shop bay (12–16 ft eave) | +$4 – $8 |
| County adder | Allowance |
|---|---|
| Franklin ($25 app + sq-ft fee + $350 escrow + sewer permit) | $1,000 – $1,900 |
| Jefferson (fee on ≥ $120/sq ft valuation) | $1,000 – $2,500 |
| Warren ($150 + $200 + $10) | $360 |
| Lincoln (no county building permit; Health Dept septic) | $0 – $300 |
| St. Charles (fee basis unverified) | $800 – $2,000 |
Site package: typical $30,000–$80,000; extended $60,000–$120,000. Example: 2,000 sq ft living + 1,200 sq ft finished shop, turnkey, typical site, Lincoln County = $416,000–$636,300.
Next step
Happy with the range? Get a quote — attach the brief and the parcel, and we start the county check. Want to understand the lines first? The cost guide · comparing builder bids.