What does building a 10,000 sqft house cost in 2026?
A colleagues parents built a 10,000 sqft custom home on the peninsula and the per sqft number that the first builder pitched at around 400 ended up being a fantasy. Final cost landed closer to 620 per sqft
The big variances came from the hillside lot which needed extensive foundation work that a flat lot estimate hadnt accounted for. Structural engineering for the second story footprint across that much square footage was its own line item. Mechanicals across 10k sqft, HVAC, plumbing, electrical, are a different animal than a normal sized home. And the wellness suite plus EV ready garage that the parents had budgeted as a minor add ended up being one of the biggest line items
At this price point the initial per sqft pitch from builders is marketing not budgeting. The actual cost depends on site conditions, structural complexity, and the real price of the high end systems that get sold as "included in the luxury package"