[Equest-users] f-factor & table a6.3 (90.1-2004 & 2007)

[Patrick J. O'Leary, Jr.]

knowing that

1) appendix a, section 6.1, references that "For the purpose of Section 
A1.2, the base assembly is a slab floor of 6 in. concrete poured 
directly on to the earth ..." meets the requirement for an unheated slab 
f-factor of 0.73, and
2) section a6.3, f-factors for slab-on-grade floors, a.6.3.1 states:  
"/F-factors/ for slab-on-grade floors shall be taken from Table A6.3", and
3) section a6.3.2 states: "These /F-factors/ are acceptable for all 
/slab-on-grade floors/."

does the "all slab-on-grade floors" really mean any thickness of 
slab-on-grade?  i.e. section 6.1 references a 6-inch uninsulated slab 
meeting the 0.73 f-factor requirement, but per sections a6.3.2 and table 
a6.3 a 4-inch uninsulated slab (or an 8-inch uninsulated slab) would 
also meet the 0.73 f-factor requirement.  so why would section a6.1 
specify a 6-inch slab when any slab thickness will suffice?  the user's 
manuals (both years) just refer to table a6.3 for f-factor values.

the state of washington has a similar section in its energy code (see 
link below), page 41, table 4-2.  section 1003.2 (also page 41) lists 
"All on-grade slab floors as assumed to be 6 inch concrete poured 
directly onto the earth."    note that on page 40, table 10.1, the 
f-factors decrease the deeper the below grade the slab-on-grade floor is.
http://ftp.resource.org/codes.gov/wa_energy.pdf
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