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SBS Modified Bitumen Specifications |
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7A.1 General Information
7A.1.1 This section provides application information, and outlines specifications currently available from JM Roofing Systems, for SBS
(Styrene-Butadiene-Styrene) Modified Bitumen Roofing Membranes.
7A.1.2 All general information contained in this section and in the current JM Commercial/Industrial Roofing Systems Manual shall be
considered part of these specifications.
7A.1.3 Specifications are available for systems installed over insulation, nailable, non-nailable, and lightweight fill substrates. JM offers
systems that can be installed using either hot asphalt or cold application cements.
7A.1.4 For hot-applied, modified bitumen roofing system applications, JM-approved asphalt is required. JM-approved asphalts are thoroughly
evaluated before they are accepted for use in any modified bitumen system.
7A.1.5 JM does not recommend the use of traditional asphalt cut-back mastics installed under any SBS modified bitumen product. The use of
cut-back mastics over the SBS modified bitumen product (e.g., to strip in the edges of a base flashing) is acceptable. JM has developed four
adhesives – MBR® Bonding Cement, MBR® Flashing Cement, MBR® Cold Application Adhesive, and MBR® Utility Cement – that are
compatible with all of the JM SBS Modified Bitumen Products; they should be used whenever a cold adhesive application is necessary or
preferred.
7A.1.6 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 who is approved for SBS Modified Bitumen Roofing Systems. Prior to issuance of any JM Modified Bitumen
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.
7A.1.6.1 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 desirable, 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.
7A.1.7 Drainage of water off any roof membrane is necessary to prolong the service life of the system. JM, therefore, has the following policy:
Drainage: Design and installation of the deck and/or membrane substrate must result in the roof draining freely, 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.
7A.1.8 Flashings: Refer to Section 8 of the current JM Commercial/Industrial Roofing Systems Manual for flashing specifications and details.
7A.2 Membrane Substrate
7A.2.1 The surface on which the modified bitumen roofing membrane is to be applied should be one of JM’s roof insulations (Fesco Board,
Tapered Fesco Board, Fesco Foam, Tapered Fesco Foam, E’NRG’Y 2, Tapered E’NRG’Y 2, 1 Ú2" Retro-Fit Board, or Fiber Glass
Roof Insulation) or an approved structural substrate. The surface must be clean, smooth, flat and dry. SBS modified bitumen roofing should
not be applied directly to foam plastic insulations, as referenced in NRCA Bulletin #9.
7A.3 Roofing Over Non-Nailable Decks
7A.3.1 These specifications are for use over any type of structural deck which is not nailable, and which offers a suitable surface to receive the
roof. Poured and pre-cast concrete decks require priming with JM Concrete Primer prior to the application of hot asphalt.
7A.3.2 These specifications are also for use over JM roof insulations – Fesco Board, Tapered Fesco Board, Fesco Foam, Tapered Fesco
Foam, E’NRG’Y 2, Tapered E’NRG’Y 2, 1 Ú2" Retro-Fit Board, and Fiber Glass Roof Insulation – or other approved insulations which
are not nailable and which offer a suitable surface to receive the roof. SBS modified bitumen roofing should not be applied directly to foam
plastic insulations, as referenced in NRCA Bulletin #9.
7A.3.3 These specifications are denoted by an "I" as the third character in the specification designation (e.g., 3CID). See the "Roof Finder
Index" in this section for further information.
7A.4 Roofing Over Nailable Decks
7A.4.1 These specifications are for use over any type of structural deck (without roof 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 suitable for use over light-weight insulating concrete decks or over fills made of lightweight insulating concrete. Consult the
"Roof Decks" section of the current JM Commercial/Industrial Roofing Systems Manual, or contact a JM Technical Services Specialist for
approval of the lightweight concrete to be used.
