Concrete core drilling is the process of drilling perfectly round holes through concrete walls, floors and other concrete structures. Concrete core drilling is the most commonly recognized use of any diamond concrete cutting tool. Concrete core drills or "core rigs" can be operated in any orientation, vertical, horizontal and even upside down thru concrete ceilings. A concrete core drill bit consists of a steel tube with diamond segments brazed or laser welded on the drilling end. The core bits are mounted on the rotating shaft of various types of concrete core drilling machines. Most concrete core drills are connected to a stand that is secured to a wall or floor with a concrete anchor and a bolt but there are also concrete core drills that use vacuum pressure to attach to a floor. There are also many different types of "hand held" core drills. Concrete core drills can be powered by electricity, hydraulic, gasoline or air power sources. Concrete core drill bits can range in diameter from 1/2 inch to 72 inches in diameter and drilling depths are virtually unlimited with the use of extensions. A solid cylindrical slug or "core" of concrete is removed from the hole after the drilling is complete. The applications for concrete core drilling are virtually endless.
Core holes are used for "utility penetrations" such as electrical, plumbing and heating but are also commonly used for venting furnaces or clothes dryers. Concrete core drilling also allows concrete structures to easily be made ready for sprinkler systems, HVAC ducts, fiber optics, phone lines, computer lines and much more. Core drilling methods are used widely in underground utilities construction, most commonly, manhole taps, underground vault taps, and wherever sewer, water, steam, air or communication lines pass through a concrete or brick structure.
Line drilling or "line coring" is similar to perforating, when core holes are drilled in a series of overlapping holes in a row, allowing for one large piece of concrete to be removed. Line coring is an effective method for cutting and removing small, square or rectangle openings of almost any thickness of concrete where other concrete sawing or cutting methods cannot be applied.
Although not recommended, concrete core drilling can be performed by an advanced "do it yourselfer" and the equipment necessary to perform concrete core drilling is readily available at your local tool rental and supply store. Most professional concrete cutting companies have a minimum charge of $250 to core a hole for you and it can take a professional as little as 10 minutes to unload his equipment, core the hole, and reload his equipment. Yet, I have seen homeowners rent the equipment and spend an entire weekend trying to core a single hole and then call a professional concrete cutter in to complete the project anyways. Just like with any trade a professional concrete cutter will make his job look easy.