Agenda - 02-03-1986 - Laserfiche WebLink

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CHAPEL HILL-CARRBORO CITY SCHOOLS Building el Hill High School - Academic Chapel g �lding This section of roof consists of a precast concrete deck with fiber- glass insulation. The roof mat is asphalt and gravel . The roofing Surface is very dry and brittle with some blistering. It is imperative that this roofing surface be restored in order to extend its life and maintain a water-tite condition. The cost of accomplishing this was quoted by Baker Roofing (if done while they were here) for $30,000.00. Ephesus Elementary School Roof construCtion is made up of a metal deck with 1-5/16" of fiber- glass insulation with asphalt felts and a top coating of asphalt bitumen and gravel. Sections B and C are in relatively good condition when compared to Section A. The bitumen flood coat on all sections has oxidized to the point of leaving a very dry and brittle condition. Section A has, developed very severe blistering problems. These seem to be coming from moisture between the layers of felt (inter- ply blisters)'. Water that is trapped within the roofing assembly expands 1500 times itself when it turns to vapor from the heat of the sun and therefore causes the blisters to appear. Eventually these blisters will break from fatigue of the felts or from being walked on by maintenance personnel and they become a water entry point, into the roofing assembly. There is also' cracking that has begun to occur on the main portion of Section A. It is evident that some major patching has been done on Section A where the cracks are appearing. These cracks seem to be a re-occurrence of some past problems . At this point, and time there has not been a wide spread loss of insulating value from water infiltration, but can be expected in the near future due to dry flood coat and blistered condition. The present insulation can be saved by installing an overlay con- sisting of mechanically fastening 3/4" of 0/C fiberglass insulation to the metal deck, through the present roofing assembly, and installing a single-ply modified bitumen system. From an economical standpoint, it would be more feasible to do the entire school since Section A represents approximately 85 percent of the total roof. The approximate cost to do the entire roof is $98,000.00.