Installation Guide

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ESP Safety Shelter Foundation
Inspection / Anchoring
Concrete Foundation Inspection
The following concrete slab requirements and inspection criteria are based upon the
engineering specifications specific to the ESP Safety Shelter. To maintain Near
Absolute Protection any variations from these specific recommendations must be
reviewed and approved by a structural engineer.
Minimum Slab Thickness must be an average 5 inches:
• To test for thickness drill several holes concentrated around area of installation; the drill
bit selected must be able to drill a minimum of 5 1/2 “deep.
o Take a piece of stiff wire and bend a small “L” on the end. The “L” must be small
enough to fit through the drilled hole and will be used to hook on the underside of
the concrete.
o Once the wire has been inserted into the hole, pull up on the wire so the “L”
catches on the underside of the concrete and mark the wire at the top side of the
concrete.
o Remove the wire from the hole and measure the distance from the “L” hook to
the mark on the wire to obtain the concrete thickness. This process will be
repeated with each hole and the measurements noted.
• If there is any doubt that the average thickness is less than 5 inches, a plan should be
put into place to cut out existing section of concrete and re-pour with proper
reinforcement.
• Concrete should also extend beyond (overhang) the ESP Safety Shelter the minimum
distance as described in the Installation Section of the Owners Manual.
Minimum Concrete Reinforcement:
• No. 4 (1/2”) rebar at a maximum spacing of 24” on center, in two perpendicular
directions.
o If you are not sure if your concrete reinforcement meets this requirement, you
should contact a contractor or building inspector for an inspection. They can
evaluate your concrete with a GPR (ground penetrating radar). These devices
can detect both ferrous and non-ferrous materials; they can also detect voids in
concrete and thickness.