Cost Per Square Foot

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Summary: cost per square foot is largely meaningless. You don't know what it means until you consider:

  1. Does it include builder's profit?
  2. Does it include livable space only? (or other such as garage or porch)
  3. Does it include basement?
  • To compare house costs properly to the OSE/OBI Seed Eco-Home, we consider new construction (median used homes are $120k lower cost [1])
  • Measured for livable space (cost to build the complete home / sf of livable space only) only as the claimed industry standard of measuring cost of a home. Thus, a large garage and porch or upscale interior finish drive the cost up [2]. Does not include land.
  • Average USA cost is $150 builder grade [3]. But this figure is different than the industry standard cost method - here they don't include land NOR non-livable space such as garage. Thus, the Forbes definition is not the standard definition.
  • Median is more useful with nonsymmetric distributions, such as ones skewed by high cost outliers such as housing. [4]. The average is higher, median is the average Joe price.
  • Average sale price of a new home USA is $487K, median is $416k [5]. Or about $190-$220/sf.
  • If average cost to build a house is $280k [6], then land + legal is $200k.
  • Median sf is 2300
  • There are 6 classes of house quality. Lowest cost is $60/sf build cost. Highest is $500/sf (luxury) [7]
  • Cob homes are the lowest cost to build, but highest cost to buy [8]. Build cost is way off - it doesn't include any MEP.
  • Summary: average cost to build a new home $300k (land not included), to buy $500k [9]. Detailed breakdown of the $500k by NAHB for what appears to be builder grade - [10]
  • OSE Value Summary: OSE build cost is $60k materials + $25k labor) for an entry-level, high quality home - $85k or $65/sf for the 1300 sf 3 bed/2 bath model, compared to the $114/sf NAHB survey average (2600 sf). The OSE cost does not include land, site prep, legal, design & engineering, overhead, profit, financing, marketing, sales, or any other fees. The NAHB cost does not include land, site prep, overhead, profit, financing, marketing, sales but does include permit, impact, engineering & design fees.


  • 2023 - $279k, 1700 sf [11]. $164/sf.
  • 2023 - $340k, 1500 sf [12]. $227/sf.