Hello everyone. I found this forum while searching for concrete foundation information, and it seems to be a good place to ask for advice. Searches of the forum have not yielded examples directly applicable to this situation.
I plan to hire a contractor to build a foundation for a mausoleum and would like to understand enough to give proposals a sanity check. I'm an EE but have little knowledge of concrete foundations.
Here's what I know:
Foundation:
Needs to be solid and stable for a long time (decades?, centuries?)
Top-view dimensions are 9'10" long x 8'0" wide
Top-view drain pit dimensions are 4'0" x 1'0"
Drain pit's 4' dimension is centered in foundation's 8' width
Drain pit's 1' dimension is 1'2" from one end of foundation's 9'10" length
Sides should rise at least ~6" above grade on all sides
Top should be flat and level
Mausoleum:
Material is granite
Weight is ~16,000 pounds
Base dimensions are 8'10" long x 7'0" wide x 6" thick
Height is 3'5"
Site:
Location is western Kentucky
Frost depth is 24" per Kentucky's 2007 Residential Code
Type of soil is unknown, most land in this area is used for farming
Appears soil has not been recently disturbed or filled
Grade rolls off about 6" over length of foundation
Low seismic activity
Tornados are a possibility
One proposal specified:
4000 psi concrete
1' thick "turn-down" walls around the perimeter
"turn-down" walls extend 24" below grade
"turn-down" walls have 2 horzontal rows of #5 rebar
one 6" from bottom, one 1'6" from bottom
8" thick top (slab)
Top slab has #5 rebar 12" O.C. with ends bending and
extending ~2' down "turn-down" walls
Minimum 4" of rock under slab
All concrete poured at same time
Does this sound adequate?
Assuming all the weight is supported by the walls, there would be 16,000 lbs. on 31.67 square feet, or 505 pounds/square foot. The lowest soil load-bearing value in Kentucky's 2007 Residential Code is 1500 pounds/square foot. This would be a 3/1 safety margin, even ignoring weight born by the slab. Is this thinking correct?
Sorry for the long post... I wanted to give as much information as possible.
Thanks in advance for you help.
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