The calculation may be accurate, but it's important to consider whether this cost includes excavation, grounds and utilities requirements. It's also vital to consider if the property needs a septic, well, lot clearing, landscaping, driveway, or if it's a wet property requiring a lot of fill and engineering. These factors may not be accounted for in urban subdivisions, but are very relevant in rural areas. The house may be $600 per sq. ft. and if unaccounted for the pre-construction cost can be another 15% to 25% of the building costs.