The NABS Nestbox Committee discontinued the nestbox approval process in February of 2012 with the acknowledgement that nestboxes of different designs may work in one geographical area but perhaps not in another. The committee urges bluebirders to consider the basic recommendations listed in the Nestbox Fact Sheet (Download PDF) before determining whether a nestbox is safe for cavity-nesting birds.
Below are links to downloadable pdf or image files of plans for building several types of nestboxes.
DANDR Nestbox (PDF)
Gilbertson Nestbox (PDF)
Peterson Nestbox (PDF)
Carl Little Bluebird Box Image(jpg)
Nest Box Predator Guards (PDF)