By Astrid Zweynert

LONDON (Reuters) - Falling house prices have made it easier to trade up from the bottom of the property ladder than at any point in the last five years, research shows.

But families looking to move from middle-sized homes into more spacious properties will find it harder because larger houses have held their value better, according to estate agent propertyfinder.com on Monday.

Two-bedroom homes have dropped more than any other property type, losing about 12 percent of their value in the past year, compared to a drop of eight percent in the value of one-bedroom properties.

"The real catalyst for house price falls has been a lack of mortgage availability, particularly for less creditworthy borrowers," said Nicholas Leeming, director of propertyfinder.com.

"This means the bottom end of the market has been more impacted by the slowdown and prices there have fallen more rapidly."

People looking to trade up from a one-bedroom property will now have to find an extra 31,000 pounds on average, compared to 41,500 a year ago.

It is also easier now to trade up from a two-bedroom home to a three-bedroom. The cost fell from 66,264 to 58,436 pounds in December 2008, due to an average drop of almost 12 percent in the value of three-bedroom homes.

But despite falling house prices it has become more expensive to move to a four-bedroom house because larger properties have held their value better, the research showed.