UNC Chapel Hill – Kenan Laboratories

Chapel Hill, North Carolina

This project at a 10 story chemistry laboratory involved removing the existing Built-up roof system down to the concrete roof deck, replacing it with a new 2-ply modified asphalt membrane roof system, and installing fall protection anchors.  The new roof system consisted of a new vapor barrier, flat and tapered polyisocyanurate insulation, gypsum cover board, and a 2-ply modified bitumen membrane system.  Construction included new sheet metal flashings and counter flashings, expansion joints, and associated blocking.

Our design also provided new concrete curbs to raise penthouse door thresholds to facilitate elevated flashing heights.  This required installation of new penthouse doors and frames.  The project added handrails to the parapet at locations where the top of the existing parapet was less than 42” above the roof membrane.  No code-required secondary drainage was present and therefore our design incorporated new scuppers cut through the parapet to provide secondary drainage.  This ensures all roof areas will be drained in the event primary drains become clogged.  The project also included the design and installation of fall arrest anchors to comply with the University’s Permanent Fall Protection Guidelines.  Unit pricing was provided for drain replacement in the event that the old drains were broken during construction or were not reusable.

The design for a plaza-deck roof area, to be replaced in an alternate, involved removal of existing materials to the concrete deck (brick pavers, sand, drainage mat, the roof system, and drain), storage of bricks for reuse, installation of a new roof system and drainage mat, installation of a new drain and sand, and reinstallation of the existing brick pavers.

During the design phase we partnered with the University and contractors to specify contractor staging and roof access locations that were pleasing to the University and acceptable to the contractor.  The areas for roof access were severely constricted and there were many underground utilities near the building.  This made crane access questionable and the University decided no crane use would be allowed.  Contractor staging areas and roof access also ensured safety was maintained throughout the construction.

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