[violet13]

New construction is rapidly getting more expensive in many of the markets where it's needed the most. While it'd be cool to point to a single factor, it's a combination of several things. People are expecting more (more square footage, higher-end finish), the government is demanding more (environmental and energy regulations), labor is getting costlier, and yes - there's NIMBYism manifesting through zoning laws and other "conservation" rules.

[llamaimperative]

In high cost-of-living areas it's the land price.

[violet13]

Not entirely, but either way, land value is tied to all of that. If the city can't grow due to zoning and conservation rules, and if you can't subdivide existing parcels, you basically have more and more money chasing the same lots.

By "not entirely", I mean that while land value often dominates, lowering it doesn't solve the problem, because even if you somehow acquired a city lot for $50k in the Bay Area, you wouldn't be able to build a house on that lot for $100k. So, solving one problem doesn't make it affordable.