Construction is not an immediate cure for homebuying affordability headaches because the bulk of the new homes being built are pricier and larger than the rest of what’s sold on the market.

My trusty spreadsheet spied a Zillow study comparing existing residences sold in May with newly constructed ones in 46 big U.S. metropolitan areas — including six in California.

Developers argue they need to build bigger homes to make the expensive land they buy, plus other construction costs, pencil out financially.

Top line

Look at California, using the median results for the six cities studied.

Sales prices ran $1.14 million for new homes or $935,000 for existing ones. So what’s being built is 22% pricier.

Why? Well, builders typically sold a 2,020-square-foot house versus 1,585 for existing ones. So the new stuff is 27% larger.

And construction’s only saving grace, costwise, is that those fortunate enough to afford new construction get a slight bargain in terms of price per square foot — $568 versus $622 for existing homes, or 9% cheaper.

Please note that this is not only a crazy California thing.

Nationally, new homes had a $418,000 median sales price versus $365,000 existing — that’s 15% higher.

New homebuyers typically got 1,990 square feet new versus 1,710 for existing homes — 16% larger.

And that translates to $210 per square foot for new versus $213 for existing — or 2% cheaper.

Details

Ponder the new versus “used” patterns within California, ranked by the price premium builders got …

• San Jose: $2.87 million median for new construction or $1.6 million for existing homes — 79% higher (the fourth-biggest gap of the 46 metros). That bought 2,360 square feet new vs. 1,600 existing — or 48% larger (No. 4). So it cost $1,213 per square foot new versus $997 existing — 22% pricier (No. 7).

• Sacramento: $745,920 median new or $575,000 existing — 30% higher (No. 24) for 2,340 square feet new versus 1,670 existing — 40% larger (No. 8) — or $318 per square foot new versus $345 existing — 8% cheaper (No. 38).

• San Diego: $1.14 million median new vs. $900,000 existing — 27% higher (No. 25) for 2,060 square feet new or 1,480 existing — 39% larger (No. 10) — or $552 per square foot new or $609 existing — 9% cheaper (No. 40).

• Los Angeles-Orange County: $1.15 million median new or $970,000 existing — 19% higher (No. 27) for 1,970 square feet new versus 1,520 existing — 30% larger (No. 16) — or $584 per square foot new versus $636 existing — 8% cheaper (No. 39).• Inland Empire: $610,805 median new versus $562,500 existing — 9% higher (No. 32) for 1,980 square feet new versus 1,720 existing — 15% larger (No. 30) — or $308 per square foot new versus $328 existing — 6% cheaper (No. 37).

• San Francisco: $1.27 million median new or $1.23 million existing — 4% higher (No. 38) for 1,380 square feet new versus 1,570 existing — 12% smaller (No. 46) — or $918 per square foot new versus $780 existing — 18% pricier (No. 11).

Bottom line

This is not just a greedy builder problem.

In large part, these pricing gaps are the result of a host of policy and marketplace challenges that make it far easier to build high-end housing.

Fancy and expensive new communities are simpler to sell politically in the regulatory process. That premium housing that’s sold to wealthier clientele usually produces fatter profit margins.

So catering to the upper crust can be a smoother sell to the investors and bankers who put their dollars behind construction plans. And so far in recent years, there are enough folks with deep pockets willing to gobble up the costlier new offerings.

Consider the 10 U.S. metros in Zillow’s study with the smallest new-to-existing price gaps. These markets essentially had little difference in price or size of these two homebuying options.

Yet in the 10 with the largest gaps, new homes were 40% larger compared with new homes — and 80% pricier. (FYI: Those 10 markets, a surprising group: Columbus, Ohio; St. Louis; Kansas City, Missouri; Philadelphia; Detroit; Milwaukee; Cleveland; San Jose; New York; and Miami.)

Look, there are no simple solutions to fix homebuying’s dramatic unaffordability problem. And relying on the easy answer — build what’s convenient — won’t work.

Yes, any new supply of housing at no matter the price point does ease inventory imbalances.

But it’s a darn slow process for any affordability improvements to trickle down from housing’s high end to help the most-stressed house hunters merely seeking a modest place of their own.

Jonathan Lansner is business columnist for the Southern California News Group. He can be reached at jlansner@scng.com.