LAWRENCE BERKELEYNATIONAL LABORATORY, BUILDINGS50AND 78 ROOF REPAIR

  • Client: Lawrence Berkeley National Laboratory
  • Location: Berkeley, CA
  • Date: 2016
  • Contract #: 7304623
  • Value: $420,655

Cerrudo was awarded the design build contract to perform roof repairs at Buildings 50 and 78. Building 78 is a 5,675 SF single story structure built into the north side of a hill. The existing roof is a concrete deck with a fully adhered built up roof and gravel cover. There are four interior roof drains. The roof has an existing air handling unit on a curb. The roof repair for Building 78 was initially designed as a three-ply modified roof system based on the RFP requirements. The client requested a change of design to a PVC membrane roof system so that the existing built up roof could remain. The new design has been completed and is under client review. Once work commences, the existing loose gravel will be removed. Tapered insulation with diamond crickets will be adhered to the roof. DensDeck primed recovery board will be installed over the tapered insulation, then the Duro-Last PVC membrane roof system will be adhered to the recovery board. The perimeter parapets will be raised and new two-piece perimeter edge metal installed. The installation work is scheduled to begin April 2017.

The new Building 50 roof over the existing library, 2,208 SF, was designed with a fully-adhered PVC membrane system. Before work commenced, fall protection delineators and warning flags were set up six feet away from the open perimeter building edge. The existing horizontal lifeline cable attached to the building wall was used for securing each workers’ personal fall restraint devices.

The existing built-up roof membrane was tested and found to contain PCB’s. The membrane was removed by workers trained in PCB removal and containment. A DensDeck cover board was installed over the concrete and corrugated metal roof deck, and rigid thermal insulation adhered over the cover board. A 40 mil PVC single ply white fully adhered field membrane with water-based adhesive was installed over the insulation, heat welded at laps. New gutters, downspouts and roof ladder were installed.