Facilities Design and Construction
The state of Wisconsin has published a very helpful guide for determining space needs for public libraries. Whether you are planning a totally new building, an addition, or just a reorganization of the space you already have, this guide will assist in providing adequate space for technology, for staff work areas, etc. (http://dpi.wi.gov/pld/plspace.html) A print copy of this guide is available for loan if you cannot download this site.
ADA Compliance - All new library buildings or buildings that are undergoing substantial remodeling must be compliant with the federal Americans with Disabilites Act. ADA Guidelines are found at: http://www.access-board.gov/adaag/html/adaag.htm
While quite out-dated, libraries that are planning space without consideration for technology can consult the Interim Standards for Small Public Libraries: Guidelines Toward Achieving the Goals of Public Library Service, Public Library Association, 1975. The "Guidelines for Determining Minimum Space Requirements" found on p. 15 of this publication are organized by population size. Available via interlibrary loan.