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minimum fc for Residential slab on grade
- To: <light_framing(--nospam--at)structuralist.net>
- Subject: minimum fc for Residential slab on grade
- From: "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
- Date: Wed, 9 Jul 2003 14:28:10 -0700
- Cc: <seaint(--nospam--at)seaint.org>
I designed a single
story residence (spec home but large) using a slab on grade which is typical in
this area. Historically, we placed f'c=2,000 psi concrete for everything but
where proprietary frames such as Hardy Frames are used. The typical soil in the
area is silty sand with a bearing pressure of 1,500 psf and with increases
allowed for depth and width.
I received a plan
check correction based on the 1998 CBC and 1997 UBC. He quoted section
1921.2.4 which requires high strength concrete but has an exception that allows
for concrete not less than 2,500 psi. This is generally required when inspection
of the concrete is called for and not for simple slab on grades. The city has,
during the 1997 UBC cycle allowed for f'c=2,000 psi concrete, but the contract
plan check company requires 2,000 psi concrete so as not to force deputy
Are there any
comments as how I should address the plan check correction since deputy
inspection can be expensive and there are no problems with subsidence or
expansive soils in the area.
Am I wrong on this
one????? If so, it comes as a surprise.