Median Incomes and Economic Obsolescence of Large Homes

One thing that has led me to believe that the housing market in Southern California is largely at bottom is the fact that many houses are selling at less than replacement cost. While such a discrepancy can exist for a long time in places with declining population, replacement cost is a pretty sound fundamental for determining the minimum sustainable house price in areas with growth.

The report on median incomes released yesterday, though, suggests to me a flaw with my line of reasoning. While the average new house has grown about 20 percent in size over the past ten years, median household incomes have actually fallen a bit. If house size is a proxy for house quality (and we have good statistical evidence to think that it is), then house quality has outstripped the ability of people to pay for it.

When comparing market prices to replacement cost, we really need to think about depreciated replacement cost. Depreciation comes in three flavors: physical, functional and economic. Physical depreciation happens because things wear out as they age–it is what Congress is thinking of when it allows depreciation deductions for investment property and plant and equipment.

Functional depreciation happens when a component of a capital asset does not perform its function well by current standards. Think of a furnace that uses lots of energy, and could be replaced by something more efficient. It is possible that it could work as a furnace for years, but it still would be best replaced by something more efficient.

Finally, there is economic depreciation, which happens when the demand for something (like Detroit real estate) disappears. It is possible that large houses have incurred economic depreciation because people lack sufficient income to afford them. If this is true, values can fall below original construction cost and stay there for some time.

Such considerations do not, of course, apply to reasonably well located, modest homes–I continue to believe that 1500 square foot houses in the San Fernando Valley and the central part of the San Gabriel Valley are reasonably priced now. But the market for larger houses may be troubled for some time yet to come.

One other implication: builders should construct smaller houses in the years to come. This vindicates a prediction I once made. Unfortunately, I made it in 1990.

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