Despite relatively strong performance by the office sector so far, a lack of new housing construction combined with double-digit housing price inflation could undermine San Diego County's job market, according to a commercial real estate analyst.

Although job growth has been furious over the last seven year s, housing hasn't even begun to keep up, Russell Valone of MarketPoint Realty Advisors told the San Diego Building Owners & Managers Association at the Hyatt Islandia Hotel on Tuesday.

The percentage of households in California able to afford a median-priced home decreased by seven percentage points in April compared to a year ago, according to a report released June 6 by the California Association of Realtors.

With an index of 22, San Diego was among the least affordable housing markets in America.

"With the median price of a home jumping nearly 30% in April to $321,950 compared to a year ago, it's no surprise that affordability posted a dramatic decline," says CAR President Robert Bailey. "Low mortgage interest rates, which averaged 7.95% in April, aren't enough to offset the increase in the cost of a single-family home in California."

Valone said just over a decade ago, a housing unit was built at a ratio of one unit for every 1.6 jobs. Today, the ratio is only about one unit per three or even four jobs.

Although the office sector is taking its lumps, it's holding its own, brokers say.

Chris Pascale of CB Richard Ellis says north San Diego County's Carlsbad, with 131,000 sf of sublease space, has helped push the area's vacancy to about 20%. Of a total market of about 2.7 million sf, he said roughly 700,000 was vacant.

Kearny Mesa, by comparison, has only 108,000 sf of sublease space in a much larger market is considered to be much healthier than Carlsbad. New office buildings are expected to add to the vacant space, including about 100,000 sf under construction in the San Diego Spectrum and another 110,000 sf in Mesa View Plaza.