Finger Lakes Building Officials, Inc.

An Affiliated Member of the New York State Building Officials Conference

June 11, 2003

Re: Support Piers for Decks
Seismic Zones D1 and D2
RCNYS R404

I am writing in response to your letter asking if it is acceptable to use pier construction to support decks in seismic zones D1 and D2. It is my opinion that this type of construction is acceptable.

A deck is defined in Chapter 2 of the Residential Code of New York State (RCNYS) as ..an exterior floor system supported on at least two opposing sides by an adjoining structure and/or posts, piers, or other independent supports. Section R404.1.5.1 does not allow pier foundations in seismic zones D and E. However, Section R404 provides prescriptive construction requirements for foundation walls supporting exterior walls of a dwelling, with no specific provisions for decks. By definition, a deck is allowed to be supported by piers and absent language to the contrary specific to deck construction, there is no basis in the code to disallow piers for deck supports in seismic zones D1 and D2.

This advisory opinion is rendered based upon the information provided. Administration and enforcement of the code are within the jurisdiction of the local authority. If you have questions regarding this advisory, please call me at (518) 474-4073.

Sincerely,
W. Roy Scott, RA
Assistant Director for Regional Services
Codes Division
Al03-136

Finger Lakes Building Officials Association, Inc.
3100 Atlantic Ave.
Penfield, NY 14526