• The country’s most affordable homes have gained 44 percent in equity over the past five years, while the most valuable homes have gained 27 percent.
• Affordable homes in Tampa, Fla., gained 20 percent in value over the past year – the largest gain among the largest U.S. metros.
• Seattle and the Bay Area are the only large markets where the most valuable homes are gaining value faster than affordable homes.

Owners of the country’s most affordable homes are gaining equity the fastest, because demand for entry-level homes continues to grow faster than supply.

The phenomenon – which has become more pronounced in the past few years — underscores the power of homeownership to build wealth. It also points to a problem with housing inventory: One reason lower-end home values are being driven up so quickly is that there’s tremendous demand and not enough homes for sale at the starter end of the market.

For this analysis, Zillow divided U.S. housing stock into equal thirds based on value and determined the median value of the most and least valuable homes.

Over the past year, homes in the most affordable segment of the market, which are often sought by first-time buyers, gained 8.5 percent in value, compared to a 3.6 percent gain for the most expensive homes. Over the past five years, the difference is even more noticeable: People who own the most affordable homes have seen their equity grow by 44.4 percent, while owners of top-tier homes have gained 26.6 percent.

Less affluent homeowners typically have more of their wealth in their homes than people with higher net worth. Owners of more affordable homes are seeing their homes’ value, and therefore their overall wealth, grow rapidly—which is good news for a segment of the population that saw their homes take the biggest hits when the housing market crashed.

Home value growth benefits people who already own homes, but it raises the barrier to entry for renters who want to buy. Inventory among the most affordable homes is extremely limited, with nearly 18 percent fewer such homes on the market now than there were a year ago. Inventory of top-third homes was down just 4.9 percent. More affluent home shoppers looking in the upper range have more homes to choose from to begin with: More than half (51.3 percent) of homes available for sale on Zillow in December were in the top-third of all homes, compared to just 22.1 percent in the bottom-third.

Affordable homes in Tampa, Fla., gained 20 percent in value over the past year – the largest gain among the largest U.S. metros. Las Vegas homeowners are close behind, with its most affordable homes gaining 19.9 percent from last year.

San Francisco, Seattle and San Jose, California are the only large markets where the most expensive homes are gaining value faster than starter homes.