There are a number of things that can delay a home sale, but CNBC’s Diana Olick outlines one problem in the home selling process that seems to only be getting worse: a declining number of home appraisers.

The men and women who value homes and whom mortgage lenders depend upon are shrinking in numbers, causing growing delays in closings while costing buyers and sellers money and in some cases even stymieing deals.

The share of on-time closings has dropped from 77% last April to 64% today for loans backed by Fannie Mae and Freddie Mac, according to Campbell/Inside Mortgage Finance. Appraisal-related issues in these delays jumped by 50 percent in that time.

"The appraisal shortage is massive. You're seeing significant delays, you're seeing cost increases, you're seeing rate [locks] expire," said Brian Coester, CEO of Rockville, Maryland-based CoesterVMS, a national appraisal management company.

Since 2007, the number of appraisers has shrunk by 22%, according to the Appraisal Institute, an industry association.

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