(MONEY Magazine) – Don't be fooled by figures some developers bandy about indicating that condominiums appreciated in value faster than single-family detached homes in recent years. There are always anomalous windfall situations in hot regions like San Francisco, but in reality condos on average continue to underperform houses. During the year that ended in June, condos rose in value one percentage point less than houses did. ''If you buy a condo just for appreciation, you're bound to be disappointed,'' warns Michael Sumichrast, editor of the monthly newsletter Real Estate Perspectives. Students of real estate markets like Sumichrast note that condominiums have historically suffered from weak demand and an oversupply that tends to depress prices -- not to mention condo sellers. On the demand side, Americans generally prefer the privacy of single-family houses to wall-to-wall condos, although the lower cost of condos makes them appealing to some first-time buyers. On the supply side, since buyer interest in condos is relatively small, developers who rush up units in a hot housing area can easily glut the market. That's what happened around Boston in 1985 when builders began putting up 5,000 condos that year. Today the condo market there is so weak that prices are flat and some developers now offer to purchase the present homes of buyers willing to move in. If you are looking for a condo as a primary residence and want to improve your chances of getting reasonable appreciation, follow these rules: -- Look for a project where most units are occupied by owners, not by tenants renting from investors. Owner-occupied condos tend to be kept up better. -- Shop for a two-bedroom condo minimum, rather than a studio, since the bigger units are more likely to hold their values, says Doug Kleine, research director of the Community Associations Institute, a condo information clearinghouse in Alexandria, Va. -- Select a development with amenities such as a shuttle-bus service for commuters or on-site day care, advises Carolyn Janik, the author of Money- Making Real Estate (Penguin, $9.95).