Builder confidence in the market for new single-family homes remained unchanged for a third consecutive month in April, according to the National Association of Home Builders and the Wells Fargo Housing Market Index.

The index held at 20, up marginally from the record low of 18 set in December 2007.

Derived from a monthly survey that NAHB has been conducting for more than 20 years, the NAHB/Wells Fargo index gauges builder perceptions of current single-family home sales and sales expectations for the next six months as “good,” “fair” or “poor.”

The survey also asks builders to rate traffic of prospective buyers as either “high to very high,” “average” or “low to very low.” Scores for each component are then used to calculate a seasonally adjusted index. Any number over 50 indicates that more builders view sales conditions as good than poor.