HVAC Penetrations Through Concrete

Mechanical work generates a steady stream of concrete penetrations: round cores for refrigerant and condensate lines, larger openings for duct chases, and roof-deck or floor penetrations for rooftop and packaged units. In Houston's tall commercial and healthcare buildings these penetrations frequently pass through post-tension slabs and composite metal decks, where cutting blind is not an option.

The right approach depends on the size and shape of the penetration. Round penetrations up to large diameters are cored; rectangular duct openings are sawn. Crews we route work to size the hole to the sleeve or duct plus the required clearance, so the mechanical contractor gets a penetration that fits the fire-stopping and sleeve detail.

Coring versus sawing for HVAC

Round holes for pipe, refrigerant, and small ducts are made with concrete core drilling, which produces a clean, sleeve-ready bore. Rectangular duct chases and larger equipment openings in slabs are cut with slab sawing; wall-mounted duct penetrations use wall sawing. For openings that combine round and rectangular geometry, crews often combine coring with saw cuts.

Every penetration through a structural slab should follow concrete scanning to locate post-tension tendons, rebar, and embedded conduit — a single cored hole through a stressed cable can compromise the slab.

Practical considerations

• Wet coring controls silica dust per OSHA 1926.1153 and keeps mechanical rooms and occupied floors clean; water management is planned for upper floors.
• Post-tension slab locations are scanned and, where a tendon can't be avoided, the penetration is repositioned rather than risking the cable.
• Overhead deck coring requires water capture rings and slurry containment to protect finishes below.
• Penetration size accounts for sleeves, fire-stop annular space, and insulation thickness.