Cutting, coring and drilling of concrete is a necessary part of the interior fit-out construction when the project requires new plumbing and electrical penetrations such as sinks or floor monuments. If not conducted properly, it can result in damages to the building structures and conduits. Inadequate preparation can also lead to worker injuries due to unanticipated findings embedded in the concrete. The best practice is to conduct scanning or x-ray first to identify and locate rebar, conduit, post tension cables and other embedded objects within the concrete target.
The choice between applying the method of concrete scanning or x-ray depends on project requirements. Both methods help to locate subsurface objects and hazards. X-ray will provide a clear precise image of the concrete interior whereas scanning will provide a general idea based on interpretations from collected data. X-ray will often times follow scanning when collected data is difficult to interpret or lack accuracy.
Approval must be obtained from the landlord and appointed structural engineer prior to any coring work. The landlord and structural engineer will require drawings that clearly indicates the coring location and proposed dates for x-ray and/or Scanning and Coring. Structural integrity and tenant impacts are the basis for approval.
Out of the two, scanning will cause lesser of an impact to the tenants. Scanning can be conducted during regular business hours as tenants are not required to vacate the area. Scanning will most likely not require access to areas above or below. Due to the use of radioactive material, x-ray will require the evacuation of a certain radius depending on the direction of shooting. Multiple floors in an office tower must be cleared at the time of x-ray. To minimize tenant impact, all x-ray work is to be conducted after hours. It is important to visit the floor below or above the direction of shooting to verify ceiling conditions. Suspended ceilings are preferred because contractors can directly place the x-ray device or film on the underside of the concrete slab surface. A major pitfall I often observe is the lack of notice provided by the contractor. Contractors are to plan ahead knowing that advanced notice (rule of thumb is a minimum of two weeks) must be provided to the landlord for tenant coordination.