Guidelines for installing concrete sign foundations
By Bill Dundas
Freestanding outdoor signs must be designed to withstand the rigors of wind and weather through-out their usable lifetimes. Installation of concrete sign foundations thus represents a crucial step impacting the overall quality and durability of projects. In addition to executing these procedures properly, it’s important for sign installers to understand the rationale for each step in the process.
Because each sign foundation begins with an excavation, verifying and locating underground utility lines in the area proposed for installation represents an essential first step. To avoid potential hazards and expenses, the installation contractor should always contact the local utility companies. Gas, water and electric firms maintain toll-free phone numbers for this purpose and, in some cases, your proposed sign installation site might need to be altered to avoid conflicts.
Once utility clearances are confirmed and the foundation’s dimensions have been clearly marked at the site, excavation work can begin. In many cases – and assuming efficient scheduling – it’s feasible to complete the excavation, assemble the concrete forms and pour the concrete within a single workday. But complex foundations for very large signs that require extensive forming and reinforcing steel (commonly known as “rebar”) might not allow pouring and finishing on the same day. In these cases, it’s extremely important to cover open excavations with waterproof tarpaulins in case of rain or snow. For safety until work resumes, the excavation site also must be properly barricaded.
Because concrete is mixed with carefully prescribed amounts of water, additional water in your excavation is undesirable. Thus, when rainwater or groundwater leaks into the excavation, it must be pumped out prior to pouring the concrete. Otherwise, this extra water weakens the entire foundation.
The two most commonly used configurations are direct-embedment and anchor-bolt foundations. In the direct-embedment type, the sign pole itself is embedded into the concrete when it’s poured. Anchor-bolt foundations utilize long, large-diameter steel bolts embedded in the concrete. The bolts are arranged in a pattern matching holes in the steel base plate welded to the bottom of the sign pole when it’s fabricated.
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