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2013-2016 Edition, NFPA 13: (3)

Question asked by maasaicontracting on Mar 28, 2020
Latest reply on Mar 30, 2020 by maasaicontracting

We have a Type 3 construction of a retrofit of 100 year old assembly building with concealed space below the 1st floor that meets all the requirements of

The AHJ has questioned us, What is (3) Tight Construction? 

There is no access doors into crawl space from the 1st floor or exterior.

Crawl space is less than 3,700 sq ft.

The contractor has cut the floor to examine the space. Floor is two to three layers of planking and hardwood about 0’-2&1/2” thick. There is wood floor joists, full 2” thick, with about 1'-0" clear space between bottom of joist and floor, varies in depth.

Floor of crawl space is dirt, rock.

NFPA 220 and 5000 does not give any description of Tight Construction.

There is no commercial kitchen in building.


It seems to be an ambiguous term left up to desecration of the design professional with approval by AHJ.

Please provide any interpretations, opinions, experience or NFPA comments. 


Merriam-Webster’s Collegiate Dictionary, 11th edition, Merriam-

Webster, Inc., Springfield, MA, 2003.