Clemson University has various types of roofing on its different facilities. Replacement of an existing roof or the design of a roofing system on a new facility may require different design parameters. In general, an existing roofing system will be replaced with a like system. Overall design will determine the type of roofing system used on a new facility. Some projects require roofing systems that are unique to the facility. Consult with the Project Manager for additional information concerning a particular facility.
The Owner has an inventory of asbestos containing materials (ACM) in existing roofing and interiors of buildings. This information is available from the Project Manager for use in preparing the specifications for any roof replacement.
Roof design should meet all applicable code requirements. The IBC has made some significant changes in regards to minimum requirements of code based on replacement, recover, retrofit or percentages to be included. The designer should be familiar with these requirements.
Standards published by the National Roofing Contractors Association (NRCA), Asphalt Roofing Manufacturers Association (ARMA), Single Ply Roofing Institute (SPRI), and the Sheet Metal & Air Conditioning Contractors National Association, Inc. (SMACNA) contain general construction and detail recommendations.
The NRCA Roofing and Waterproofing Manual, 5th Edition and the SMACNA Architectural Sheet Metal Manual, 6th Edition are excellent sources of details and criteria for roofing and roof accessory design.
Do not write specifications that allow an undetermined roofing manufacturer to determine the acceptability of a condition or detail to be used.
Provide an existing roofing plan showing actual field dimensions, actual conditions, penetrations, roof mounted equipment, and any core sample information or summaries. Indicate any equipment or penetrations that are to be abandoned. Consult with the Project Manager to determine what equipment and/or penetrations can be abandoned.
Provide a new roofing plan, identifying slopes, penetrations, equipment, and any other details necessary to provide adequate information to the contractor. The use of isometric details is preferred where applicable.
Access to the roof should be via interior stairs or interior ladders to roof hatches, not exterior ladders. Protective mats or pads should be strategically placed at exit/entry points and anticipated heavy travel areas on the roof.
Coordinate the installation of any required lightning arrestor system and adequately address the need for certification or recertification of the system. Specify that the system be made operational at the end of the work day.
Use crickets, saddles, and edge strips to direct water way from penetrations and parapet walls to ensure positive drainage to scuppers, drains, and gutters. Provide twice the primary slope to ensure proper drainage from penetrations and parapets. A minimum distance of twelve (12) inches between roof penetrations should be maintained to allow for proper flashing details.
Whenever possible, avoid the use of pitch pans. When existing pitch pans cannot be eliminated, specify a preformed pan with a minimum height of four (4) inches, four (4) inch flange, and a minimum clearance of two (2) inches on all sides of the penetration. The pitch pan should also include the appropriate hood or umbrella.
Use round shapes for equipment supports. These supports should be a minimum of fourteen (14) inches high, with higher supports necessary for larger pieces of equipment.
Locate interior roof drains at mid spans and low points of the roof deck. Do not locate drains at columns. When flashing drains, taper insulation twenty-four (24) inches around drain. Extend membrane, lead flashings, and strip flashing under drain bowl clamping ring. Do not use exposed lead sump pans.
The designer should specify that the contractor will confirm, prior to commencement of roofing activity or demolition, in the presence of the appropriate Facilities personnel, that existing roof drains are open and functioning properly. The method of protection of roof drains during construction should also be specified.
Clemson University has a number of facilities with tile roof systems. Many of these facilities are considered to be part of the historic resources of the University. The replacement of roof systems on these facilities should be coordinated with the design information and guidelines available in the Planning and Design office. Consult the Project Manager for additional information.
Clemson University has utilized built-up bituminous roofing, modified bituminous membrane roofing, and elastomeric membrane roofing systems on its facilities. Each facility should be analyzed with the Project Manager to determine the type of roofing in this category to be used.
A minimum slope of ½” per foot is required on these types of roofs. In the case of some large roof areas, if this slope cannot feasibly be attained without excessive parapet wall heights, a slope of ¼” per foot may be acceptable in those cases. Exceptions to ½” slope conditions must be approved by the Project Manager.
Membrane roofing system requiring the use of hot asphalt kettles, the designer should take special care in reviewing possible acceptable locations for these kettles, in accordance with applicable fire codes, and in no instance be allowed on the roof itself. The Project Manager can coordinate possible locations with the Clemson University Fire Marshal. Due to objectionable odors created by asphalt kettles, the use of low emission kettles should be specified and required, as well as the actual location of the kettle to minimize infiltration of odors into the building or surrounding buildings.
The actual design of the type of built-up roofing may depend on the several factors concerning the facility. The standard of design for built-up roofing systems consists of a 3-ply built-up system with a cold applied modified bitumen cap sheet.
Due to the large number of elastomeric membrane roofing systems on the market, if one of these systems is to be utilized on a project, thorough research and investigation of the approved system should be done. Most single ply systems at Clemson University have been some type of Ethylene-Propylene-Diene-Monomer (EPDM). An elastomeric membrane system should not be specified without written approval from the Project Manager.
Clemson University has employed different types of sheet metal roofing systems on its facilities. Location, use of the facility, expected life of the system, and architectural considerations can be factors in determining the type of metal roofing system that may be used on a facility.
Sheet metals incorporated into roof systems should have the equivalent life expectancies of the adjoining roofing system and be compatible with the architectural intent of the facility.
Do not specify interior or built-in gutters, and built-in downspout systems unless unavoidable or their use is of primary architectural importance in the historical district (see Campus Master Plan). Material selection for gutter and downspout systems shall use the same guidelines as indicated for other sheet metal flashing and trim (see Section 07 60 00 above).
Clemson University has limited installations of roof deck paver systems on their facilities. The Project Manager can assist in the use of this type of system if needed.
Tamko, Johns-Manville, or GAF
DynaFlex by Johns-Manville
Awaplan Premium by Tamko
Ruberoid by GAF
DynaGlas by Johns-Manville
Awaplan Premium FR by Tamko
Ruberoid Mop FR by GAF
Smith Series 1010 –Y-R-C-G
Wade Series W-3000-NH-40-52-53
Exposed Joints: Dow Corning 790,SikaFlex 1A, or Tremco Mono
Interior Joints: Dow Corning 790 or Tremco Caulking Compound