Construction & ContractorsNAHB Phase Model
House Construction Cost Calculator
Calculate single-family custom home construction costs based on NAHB phase breakdowns, garage size, and contractor fees.
Calculation Results
NAHB Turnkey House Building Formula
Total Turnkey House Cost = (Site Work + Foundation + Framing + Exterior + MEP + Interior + Garage/Porches) × (1 + Builder Fee %)- Living Area (Finished): Conditioned interior space driving primary framing, drywall, HVAC, and flooring.
- Unconditioned Area: 2-car garages (~$45/sq ft) and covered porches/decks (~$35/sq ft).
- Builder Fee & Permits: General contractor management margin (15%) plus architectural & engineering permits (6%).
- Regional Cost Index: Calibrated multiplier (0.85 in low-cost regions to 1.35 in major coastal metros).
Step-by-Step Worked Example
Scenario: Building a 2,400 sq ft home with a 440 sq ft 2-car garage at national average cost index
Calculation Steps:
- Site Work & Foundation = 2,400 × ($8.50 + $16.00) = $58,800
- Framing, Trusses & Exterior = 2,400 × ($36.00 + $22.00) = $139,200
- Major Systems MEP & Interior = 2,400 × ($26.00 + $42.00) = $163,200
- Garage & Porch = (440 × $45) + (160 × $35) = $25,400
- Direct Hard Cost = $58,800 + $139,200 + $163,200 + $25,400 = $386,600
- Builder Fees & Permits (21%) = $386,600 × 0.21 = $81,186
- Total Turnkey Build Cost = $386,600 + $81,186 = $467,786
Result: The total estimated turnkey house construction cost is $467,786 ($194.91 per sq ft of finished living area).
How to Use This Calculator
- 1Enter the finished heated/cooled living area.
- 2Include attached garage square footage and exterior covered porch spaces.
- 3Adjust the regional cost multiplier if building in a high-cost or rural market.
Assumptions & Limitations
- Estimates are based on standard national averages and current prevailing construction materials and contractor rates.
- Actual trade bids may fluctuate according to local building code requirements, permit fees, and site topography.
- Always obtain multiple written bids from licensed, bonded, and insured contractors before commencing work.
Frequently Asked Questions
Does this cost include the building lot or land purchase?
No. Land acquisition, utility hookups from the street, and municipal tap fees vary dramatically by municipality and are calculated separately from structure costs.
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