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Built-Up Roofing Specifications |
6.1 General Information
6.1.1 The following section covers the application specifications currently available from Johns Manville (JM) for built-up roofing membranes.
6.1.2 All general information contained in this section and the current Johns Manville Commercial/Industrial Roofing Systems Manual should
be considered part of these specifications.
6.1.3 Specifications are available for systems installed over insulation, nailable, non-nailable and lightweight insulating fill substrates. JM
offers systems that can be installed in hot asphalt .
6.1.4 For hot applied built-up roofing system applications, JM approved asphalt is required. Asphalts are thoroughly evaluated before they are
approved for use in any JM built-up roofing system. JM acknowledges that some specifiers choose to use coal tar pitch in built-up roofing
systems. However, the use of coal tar pitch is not eligible for use within JM Roofing System Guarantees.
6.1.5 Each specification in this section is eligible to receive a JM Roofing Systems Guarantee. The system must be installed by a JM
Approved Roofing Contractor that is approved for Built-Up Roofing Systems. Prior to issuance of any JM Built-Up Roofing System Guarantee,
the JM Approved Roofing Contractor must provide an Asphalt Confirmation Number indicating that the asphalt for the project was registered
and that an "approved" asphalt source was used. Refer to the information on Guarantees in the current JM Commercial/Industrial Roofing
Systems Manual, or contact the nearest JM sales representative.
6.1.6 This manual clearly differentiates between requirements and recommendations. This manual has been written to assist the specifier
to develop a comprehensive bid package. The information is presented in an explanatory fashion rather than the authoritative, instructive
manner commonly utilized in construction specifications. When experience, technical knowledge, or established testing procedures support a
policy or position, it is clearly identified, (i.e., "JM requires" or "is not acceptable"). When the use of a particular product or practice is
undesirable or questionable, the reference is stated as an opinion rather than an absolute fact, (i.e. "JM recommends" or "JM suggests"). It
is mandatory that all requirements be complied with, however it may not be necessary to follow all recommendations to qualify
for a Guarantee.
6.1.7 Drainage of water off any roof membrane is recognized as being critical to the proper performance of any roofing system.
6.1.8 Drainage: Design and installation of the deck and/or substrate must result in the roof draining freely and to outlets
numerous enough and so located as to remove water promptly and completely. Areas where water ponds for more than 24
hours are unacceptable and will not be eligible for a JM Roofing System Guarantee.
6.1.9 Flashings: Refer to Section 8 in this manual on Flashing Specifications.
6.2 Membrane Substrate
6.2.1 The surface on which the built-up roofing membrane is to be applied should be one of JM’s roof insulations (Fesco, Tapered Fesco,
Fesco Foam, Tapered Fesco Foam, E’NRG’Y 2, Tapered E’NRG’Y 2, Fiber Glass Roof Insulation or ½" Retro-Fit Board) or an approved
structural substrate. The surface must be clean, smooth, flat and dry. Built-up roofing should not be applied directly to foam plastic insulations,
as referenced in NRCA Bulletin #9.
6.3 Built-Up Roofing Over Non-Nailable Decks
6.3.1 These specifications are for use over any type of structural deck which is not nailable and which offers a suitable coating to receive the
roof. Poured and precast concrete require coating with JM Concrete Primer prior to the application of hot asphalt. Pre-cast concrete panels
also require a layer of approved roof insulation prior to installing a roof membrane.
6.3.2 These specifications are also for use over JM roof insulations (Fesco, Tapered Fesco, Fesco Foam, Tapered Fesco Foam, E’NRG’Y
2™ , Tapered E’NRG’Y 2, Fiber Glass Roof Insulation and ½" Retro-Fit Board) or other approved insulations that offer a suitable surface to
receive the roof. Built-up roofing should not be applied directly to foam plastic insulations, as referenced in NRCA Bulletin #9. These
specifications are not to be used over lightweight insulating concrete decks or over a fill made of lightweight insulating concrete.
6.3.3 Non-nailable specifications are denoted by an "I" as the third character in the specification designation (e.g., 4GIG). See the "Roof
Finder Index" in this section for more information.
6.4 Built-Up Roofing Over Nailable Decks
6.4.1 These specifications are for use over any type of structural deck (without insulation) which can receive and adequately retain nails or
other types of mechanical fasteners recommended by the deck manufacturer. Examples of such decks are wood and plywood. Certain
specifications are eligible for use over lightweight insulating concrete decks or over fill made of light-weight insulating concrete. Contact a JM
Technical Service Specialist for approval of the lightweight fill to be used.
6.4.2 Nailable specifications are denoted by an"N" or an "L" as the third character in the specification designation (e.g., 4GNG, 4GLG). See
the "Roof Finder Index" in this section for more information.
6.4.3 One ply of sheathing paper must be used over wood board decks under the base felt.
6.4.4 All of the specifications in this section require the use of a nailable base felt. Use nails or fasteners appropriate to the type of deck. See
fastener data in the Roof Deck section.
6.5 Application of Materials
6.5.1 The proper application of roofing materials is as important to the satisfactory performance of the roof membrane as the materials
themselves. JM suggests the following guidelines for application of all roofing materials.
