A large, drilled concrete column that extends deep into the ground to carry building loads to solid soil or rock.
A deep foundation element that transfers loads through weak near-surface soils to stronger soils or bedrock at greater depth. Piers are typically larger in diameter than piles and are often drilled and filled with reinforced concrete. They may also refer to isolated masonry or concrete supports for bridges, elevated structures, or heavy equipment.
Pier foundations are a high-variability cost driver, and bid accuracy hinges on the geotechnical report's required tip depth, which determines drilling footage and concrete volume. Estimators who don't carry contingency for variable rock or refusal depths risk eating overruns, since differing site conditions and obstruction allowances are common change-order triggers on drilled-pier work.
Reading the soils report, an estimator prices 28 drilled piers at 24-inch diameter to a 20-foot rock-bearing depth, then adds a unit-price line for additional footage in case actual rock is deeper than the boring logs indicate.
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