Template:ASM Guarantee Standards

How to use the Guarantee Standards section

This section contains the Standards, Guiding Principles, Recommendations and reference materials necessary for the design and installation of a roof qualifying for a RoofStar Guarantee.

All relevant Standards for the selection and application of materials necessary to qualify for a RoofStar Guarantee are found in this section. Readers are advised to review relevant materials that can be accessed through the links available in the body of text or embedded in section titles; these are shown in blue font. Subsection titles shown in blue indicate links to more relevant material that the reader is advised to consult.

Content in this section is colour-coded according to four classes:

Guarantee Standards

Guiding Principles

Recommendations

Reference materials

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ARCHITECTURAL CONCEALED FASTENER METAL ROOFING SYSTEMS ONLY

1 GENERAL

1. Architectural Metal Roofing Systems that are accepted for use in the RoofStar Guarantee Program are roll formed, non-structural (not designed to carry normal live loads), hydrokinetic (water-shedding) systems that must be installed over solid roof decks or rigid insulation panels. Although some metal panels may also be designed for use as structural (spanning member) systems, only their use as an architectural metal panel system (over solid deck) is accepted in the RoofStar Guarantee Program.
2. Metal roofing panels are roll formed in full rafter length pans that are fastened to decks with metal clips and screws, or that are manufactured with perforations or slots to facilitate concealed fastening. Galvanized steel and wood are the most common deck materials used with architectural metal roofing. (Refer to 3 Securing the Roof Assembly).

1.1 References

In this manual, all references

1. to the British Columbia Building Code or other standards presume the current edition that is in force
2. to materials are assumed to be Accepted by the RGC, unless stated otherwise

1.2 Definitions

In this manual,

Architectural Sheet Metal and ASM are used interchangeably.

Design Authority means the individual or firm responsible for the issuance of Project specifications and details to which the Project will be bid and constructed. When a Contractor designs a Project, the Contractor is deemed to be the Design Authority.

Contractor (“contractor”) means the installer of a roof assembly or system. For the purpose of issuing a RoofStar Guarantee, Contractor shall be read to mean a Member of the RCABC.

Project means the designed or constructed ASM roof assembly or system.

1.3 Design Considerations

1. Compliance with RoofStar Guarantee Standards is mandatory for issuance of the RoofStar Guarantee certificate. The reader is urged to review all the sections of this Manual for RoofStar Guarantee Standards applicable to all aspects of the design.
2. The RoofStar Guarantee Program covers only architectural metal roof systems applied over solid decking. Structural metal roof systems requiring metal panels to span framing members unsupported by solid decking are not covered under the RoofStar Guarantee Program.
3. Repairs or renovations to an existing roof system that is not covered by a RoofStar Guarantee do not qualify for a RoofStar Guarantee. Renovations are defined as the partial removal and replacement of a metal roof system. To qualify for a RoofStar Guarantee, the roof system must incorporate new materials, unless provided otherwise by a written Variance issued by the RoofStar Guarantee Department prior to tendering. Modifications or additions to a guaranteed roof are permissible, subject to various conditions, but must be made by a Contractor qualified to perform work under the RoofStar Guarantee Program.

1.3.1 Engineered Designs:Structural

1. To qualify for a RoofStar Guarantee, all Architectural Sheet Metal roofs must be professionally engineered and documented on a Schedule S form (Specialty engineering; see the BCBC, current edition). Roofs must be engineer-designed to
   1. withstand all anticipated live and dead loads, including but not limited to wind and other environmental loads (i.e. rain, snow) expected for the building’s size and location (see 1.3.3 High Snow Loads below).
   2. accommodate thermal expansion and contraction of the roof system components.
2. Each engineered designs must include, without limitation, the following:
   1. Metal panel profile and gauge
   2. Type of clips
   3. Bearing plates
   4. Drag load components
   5. Fasteners (type, size and spacing)
   6. Roof assembly components (i.e. underlayment, insulation)
   7. Deck Substrate

1.3.2 Detail Review

1. Shop drawings for each Project detail, which may be drawn by the roofing contractor, must be reviewed by the Accepted Observer and returned to the RCABC for conformity to the RoofStar Guarantee Standards prior to the start of construction.
2. Each construction detail must be reviewed during a Project field observation and documented in the RGD field review report, to verify conformity to the RoofStar Guarantee Standards.

1.3.3 High Snow Loads

1. In this Manual, a high snow load area is considered a regional area with a Specified Snow Load higher than 3.5 kPa.
2. To determine whether or not a building is located in a high snow load area, the Design Authority must calculate the anticipated snow loads for the roof, using the building code having jurisdiction. The following references are extracted from the British Columbia Building Code:
   1. Div. B, 4.1.6.2 Specified Snow Load (see the formula for calculating snow loads)
   2. Div. B, Appendix C, Table C-2 which lists various types of loads, including snow loads, for specific reference locations throughout the province.
3. Consideration should be given to
   1. slope
   2. entrances and exits
   3. penetrations
   4. valley construction
4. Roofs subject to high snow loads require
   1. full support for metal panels
   2. a minimum slope of 1:1.5 (8"/12")
   3. a self-adhered modified bituminous membranes as eave protection and underlay
   4. placement of penetrations near the ridge line

1.4 Contractor Qualifications

1. Supervision, manufacturing and installation of a RoofStar-guaranteed metal roof system may be conducted only by established employees of Contractors who possess at least one of the following valid qualifications:
   1. Architectural Sheet Metal Journeyperson Certificate of Qualification
   2. Sheet Metal trade ticket, together with at least five (5) years of documented experience installing and supervising the installation of ASM roofing or
   3. Roofing, Damp & Waterproofing trade ticket, together with at least five (5) years of documented experience installing and supervising the installation of ASM roofing

Refer to RCABC Policy A-248 and RCABC Policy A-107 Subcontracting.

1.5 Replacement Roofing and Additions

1. Where a new roof is tied-in to an existing roof, the two areas must be isolated and separated by a properly constructed curb joint that is
   1. at least 125 mm (5”) in height
   2. securely attached to the structure
   3. sealed and flashed in keeping with the requirements for curbs (see 11.3.1 Curbs)

If job conditions or aesthetic considerations do not allow for a curb joint, written permission must be obtained from the RoofStar Guarantee Program department to eliminate curb joints; a positive water cut-off must be installed to the deck to isolate the existing roof from the new roof.

1.6 Workmanship

While integrity and functionality of a new roof or waterproofed deck is the foundation of a RoofStar Guarantee, it is no less important to ensure that the end product exhibits excellent workmanship.

2 SUPPORTING DECK STRUCTURES: Decks and Walls

2.1 Roof Slope

1. A minimum slope of 1:6 (2" in 12") is required. Where the designed slope is less than 1:4 (3/12), the engineered shop drawing package must be accompanied by manufacturer’s literature confirming that this application is acceptable.
2. Roofs with designed slopes less than the stated minimum (such as curved applications; see also 9 PANELS) will be considered for a RoofStar Guarantee provided
   1. the design and installation details are submitted in writing to the Guarantee Program Administrator prior to the tendering of documents
   2. a written Variance is issued by the RoofStar Guarantee Program prior to close of tender
3. If proprietary systems are specified, the manufacturer's suggested minimum slope and application procedures must be followed in addition to RoofStar Guarantee requirements.

2.2 Supporting Deck Types

2.2.1 Wood Decks

1. All wood decks
   1. must be affixed to the supporting framing or structure with corrosion-resistant
      1. wood screws
      2. spiral nails
      3. ring shank nails
   2. with knots or cracks must
      1. have metal affixed over them before the deck can be accepted for roofing (this work should be done by others)
      2. be overlaid with a layer of knot-free 12.5 mm (1/2”) plywood
2. The structural suitability of the fastener is the responsibility of the Design Authority.
3. Plywood with a minimum thickness of 15.9 mm (5/8") is the only acceptable sheathing to be used for wood roof decking, unless applied over a solid lumber decks (including, without limitation, laminated timber and wood board decks). Tongue and groove plywood sheathing with a minimum thickness of 15.9 mm (5/8") is required for decking on all copper and zinc non-ferrous (i.e. copper, zinc) metal panel roof systems.
4. OSB (sheathing) is not an acceptable wood deck.

2.2.2 Steel Decks

1. Steel decks must conform to one of the following specifications:
   1. ASTM Standard Specification A653 / A653M, Sheet Steel, Zinc-Coated (Galvanized) by the Hot-Dip Process, Structural (Physical) Quality, minimum Grade 33, with a design thickness of 22 gauge (0.759 mm) or greater and a minimum zinc coating designation Z275.
   2. ASTM Standard Specification A792 / A792M, Steel Sheet, Aluminum-Zinc Alloy-Coated by the Hot-Dip Process, General Requirements, minimum Grade 33, with a design thickness of 22 gauge (0.759 mm) or greater and a minimum aluminum-zinc alloy coating designation AZ150.

2.2.3 Concrete Decks

1. Direct contact between metal roofing and concrete, light concrete, stone and mortar must be avoided. The selection of a suitable underlay, insulation, and method of attachment to a concrete deck or wall is the responsibility of the Design Authority.

2.3 Walls

1. Wood or steel-stud walls must be sheathed with a material suitable for securing metal flashings.
2. For concrete walls, refer to 2.2.3 Concrete above.

3 SECURING the ROOF ASSEMBLY

3.1 General

3.1.1 Design and Testing

The Design Authority is responsible to design the securement of the roof assembly, as required under 1.2.1 Engineered Designs: Structural. The following information is a reference tool for designers, to be used at their own discretion.

The RoofStar Guarantee Program (RCABC Guarantee Corp., or RGC) initiated an investigation to establish the wind uplift resistance of architectural concealed fastener metal roof systems for use in British Columbia. The wind uplift tests were carried out at the Dynamic Roofing Facility at National Research Council, Institute For Research In Construction (NRC / IRC).

NRC / IRC report No.B1040 –3 (see ASM Application Guides and Notes) provides a simplified procedure for wind uplift design for roof assemblies with architectural metal roof coverings. In addition, NRC / IRC reports No. B1040-1 and B1040-2 provided the wind resistance test results for RoofStar-accepted metal panel systems and assisted the RoofStar Guarantee Program in developing guarantee standards and acceptance criteria for the Architectural Concealed Fastener Metal Roof Systems that are accepted for used in the RoofStar Guarantee Program.

3.2 Materials

3.2.1 Fasteners, Clips and Cleats

1. For specific requirements, see below under Sections 9, 10 and 11.

3.3 Application

1. Concealed fasteners should provide clearance for the underside of the metal panel and must be of a material compatible with the metal clip.

4 ACCEPTED MATERIALS

NOTE: Click here to view all the Materials accepted for use in the RoofStar Guarantee Program.

4.1 General

1. All roofing components installed by the contractor must be
   1. new
   2. accepted by the RoofStar Guarantee Program
   3. manufactured, or listed as acceptable by, the panel manufacturer
2. All materials must be protected from weather, properly stacked and secured above ground or the roof surface and covered by wrappers approved or recommended by the manufacturer.
3. All installed roofing materials that are susceptible to moisture damage must be made watertight by the end of each work day.
4. A Primary Material is a roofing, waterproofing or water-shedding material which is directly exposed to the weather and which is primarily responsible for protecting secondary materials, and the building interior, from water and weather generally. Membranes, metal panels or shingles form the core of this material type.
5. A Secondary Material is one which forms part of the roof or waterproofing assembly and which may affect the wind resistance characteristics of the entire assembly, but is not necessarily exposed to the weather.
6. Metals and fasteners must be compatible with each other, to avoid galvanic corrosion which can occur when dissimilar metals come in contact with each other. The size of fasteners shall be determined by the Design Authority.

5 DECK and WALL OVERLAYS

NOTE: See more information in Deck and Wall Overlays.

5.1 General

1. A roof deck overlay is installed as part of the Roof Assembly, on the top surface of the roof deck but beneath the roofing materials. These products are most commonly affixed to steel decks to provide a level surface for the roof membrane or air or vapour control layers, or to serve as a thermal barrier between the roof deck and combustible insulation. Roof deck overlay materials may also be applied to other types of supporting deck structures, depending on the roof design criteria.

5.2 Materials

1. Deck and wall overlays must be suitable for, and compatible with, any membrane or panel application. Plywood, measuring at least 12.5 mm (1/2”) in thickness, is acceptable as a deck or wall overlay.
2. When the Building Code having jurisdiction requires a thermal barrier, an accepted deck overlay must be specified and installed.
3. Walls that require resurfacing for membrane application must be covered with an accepted wall overlay. See Accepted Wall Overlays.
4. See also Accepted Deck Overlays.

5.3 Application

5.3.1 General

1. Deck overlays must be
   1. fully or intermittently supported along all edges by the deck
   2. installed in a staggered pattern (offset) at least 300 mm (12") from adjacent board rows. A minus offset tolerance of 50 mm (2") maximum will be permitted to compensate for variance in the manufacturer's tolerance of differing board widths and lengths.
   3. affixed to the deck with either
      1. mechanical fasteners, and/or
      2. proprietary polyurethane foam adhesives acceptable to the primary roof system manufacturer to meet or exceed the requirements set out in 3 SECURING the ROOF ASSEMBLY.
   4. independently fastened to the deck
      1. with at least four (4) fasteners (with plates) per 1200 x 2400 (4’x8’) sheet, or
      2. as specified by the Design Authority.
2. Wall overlays
   1. must be applied to existing sheathing where sheathing is not an acceptable substrate
   2. may be mechanically fastened or adhered

5.3.2 Steel Decks

1. Deck overlays used as a thermal barrier to achieve a specific fire rating must conform to the applicable code and insurance requirements for the roof assembly.
2. When the roof assembly is uninsulated, the deck must be overlaid to provide a continuous layer of support. The deck overlay must be at least one layer of 12.7 mm (1/2”)
   1. moisture resistant gypsum core board deck overlay board, or with
   2. plywood

5.3.3 Wood Decks

1. A mechanically-fastened overlay board is required for any deck structure that does not meet the deck fastening criteria set out in 2.2.1 Wood Decks.

5.3.4 Concrete Decks

1. While metal panels must be separated from a concrete deck to prevent corrosion, a deck overlay is not mandatory and separation may be made with an underlayment.

5.3.5 Walls

1. Where the wall surface is unsuitable to receive a membrane, it must be covered with an accepted overlay material.
2. Wall overlays must be
   1. mechanically fastened with screw fasteners placed
      1. at the perimeters
      2. at the corners
      3. in the field, spaced no less than 300 mm (12”) O.C. vertically and horizontally, or in alignment with structural supports of the overlay panels.
   2. adhered with a polyurethane adhesive, applied with a continuous z-patterned ribbon spaced no less than 300 mm (12”) apart, in alignment with structural supports.

6 AIR and VAPOUR CONTROLS

6.1 General

6.1.1 Intent

Air and vapour control layers, along with thermal barriers, water resistive barriers and water-shedding surfaces, serve to separate the outside environment from the interior environments of a structure. Continuous air control layers are perhaps the most critical. Building Codes in force in each jurisdiction, and the National Energy Code (2011), require the selection and proper installation of “a continuous air barrier system comprised of air-barrier assemblies to control air leakage into and out of the conditioned space” (NEC 2011).

Continuity of the air and vapour control layers from the wall systems and roof systems is essential to the satisfactory performance of either or both. Therefore, proper connection between air and vapour control systems is essential, and the responsibility of both the Design Authority and trades constructing walls and roofs.

Air control layers control “flow of air through the building enclosure, either inward or outward” (Guide for Designing Energy Efficient Building Enclosures, Homeowner Protection Office). Controlling air flow into and out of conditioned spaces affects the performance of “thermally efficient enclosure assemblies” (ibid), impacts the potential for condensation in between materials, and directly influences rain water penetration of the building envelope. Some air control layers are considered permeable, others air-impermeable or ‘airtight’. The suitability of one over the other, in the application of a roofing system, is left to the discernment of the Design Authority. Consequently, the RoofStar Guarantee Program strongly recommends that designers and builders of roof systems intended to qualify for a RoofStar Guarantee carefully consider the regulatory design and installation requirements for effective, continuous air control systems.

Vapour control layers regulate or prohibit the movement of water vapour from one space to another by means of diffusion. Consequently, these control layers are referred to as either vapour-permeable or impermeable. Diffusion is a slow process, in contrast to air movement, and its regulation is not always mandatory or even desirable. Consequently, because continuous vapour control layers “are not needed within all climate zones and assemblies”, they are considered non-critical and may be left to the discretion of the Design Authority. Nevertheless, where continuous vapour control layers are required and specified by provincial or municipal building codes (current and in force), the RoofStar Guarantee Program requires that a suitable vapour control system be selected by the Design Authority and properly installed by the roofing contractor in conformity with the vapour control layer manufacturer’s published instructions, and with the Design Authority’s specified details.

Any references in this Manual to installation methodologies, and any construction details that show air and vapour control layers, are merely illustrative and not prescriptive. Installers of continuous air and vapour control layer systems are urged to understand and comply with best practices for their application.

6.1.2 Limitations and Exclusions

1. Air and vapour control layer performance is not part of the RoofStar Guarantee, and air and vapour control materials are not listed in the Accepted Materials section of this Manual. Therefore, the decision to specify air and vapour control layers, the placement of continuous air and vapour control layers in relation to a roof assembly and its components, and the selection of suitable materials for that application, is the sole responsibility of the Design Authority. The Design Authority is urged to review and consider the performance characteristics of materials available for such applications.
2. Neither the RoofStar Guarantee Program nor the roofing contractor will accept any responsibility for damage to, or failure of, the roof system caused by the use or absence of air or vapour control layers.
3. In some roof assembly designs, the required underlayment may serve as an air control layer, vapour control layer, or both; this is dependent upon the properties of the material to be used, and will be subject to the designer’s modelling of the assembly. Consult the Technical Data Sheets for suitable materials.

6.1.3 Vapour Retarder Design for High-Humidity Building Interiors

1. Careful consideration should be given to the performance characteristics of air and vapour control layers when specifying such a membrane for roof assemblies constructed over high-humidity building interiors. Roof systems for these types of facilities may be susceptible to the accumulation of moisture within the roof assembly unless effective air and vapour controls are installed. These types of building interiors include (but are not limited to)
   1. Swimming pools
   2. Commercial laundry facilities
   3. Large aquariums
   4. Paper mills

6.2 Materials

1. The material selected for air and vapour control layers must be compatible with any other materials in the roof or wall assembly to which the control layer may come in contact. This includes, without limitation, contact with primers and adhesives, substrates, solvents and cleaners.
2. Fully supported air and vapour control layers should possess a minimum published static puncture resistance rating of 150 N (34 lbf) (ref. CGSB-37.56-M for both test method and standard limits) and be either self-adhering or torch-applied; a high puncture resistance is necessary for the membrane to withstand accidental damage during construction. For unsupported air and vapour control layers, see 6.2(3) below. Therefore, while responsibility for the selection of suitable air and vapour control layers rests with the Design Authority, a roof designed and built to qualify for a RoofStar Guarantee shall not include either polyethylene sheet plastic or bitumen-impregnated kraft paper.
3. Notwithstanding any of the foregoing, the RoofStar Guarantee Program strongly recommends that any air and/or vapour control systems be installed over a smooth, continuous plane (for example, concrete or plywood). Consequently, a deck overlay board installed on corrugated steel roof decks in highly recommended. Where no deck overlay board is installed and the air and vapour control layers are partially unsupported (for example, on a steel deck), the control layers each must have a published static puncture resistance of at least 400 N (90 lbf). Furthermore, both the side laps and end laps must be fully supported.
4. Should the air or vapour control layers be used as a temporary roof during Project construction by either the roofing contractor or by other trades, a minimum 2mm thick bituminous membrane is recommended.
5. Because curing concrete releases considerable moisture that can compromise the performance of a roof system, a vapour control layer installed on new concrete decks (28 days or older) must be selected to prevent condensation inside the roof system. A membrane with a permeability of 0.01 perms (Class I) is recommended. Nevertheless, the selection of the vapour control material is the responsibility of the Design Authority.

6.3 Application

1. Proper installation and continuity of air and vapour control layers within the roof assembly is the responsibility of the roofing contractor. Therefore, air and vapour control layers in the roof assembly must
   1. extend beyond the end of the roof assembly at least 100 mm (4”), in new construction, to provide sufficient room for the installation of matching control layers to so that they provide a positive (water-shedding) lap seal union between courses of material
   2. be sealed to matching control layers in the wall assembly, for roof replacement Projects
2. Installation must conform to the manufacturer’s published requirements and the Design Authority’s design details.

7 INSULATION

7.1 General

7.1.1 Definitions

Heat-sensitive insulation means insulation that may be physically or chemically altered when exposed to heat greater than 70°C (158°F) - for example, heat from a torch or from liquefied bitumen. Heat-sensitive insulation includes EPS, XPS and Polyurethane.
Heat-resistant insulation means insulation that resists heat and will not physically or chemically change when exposed to heat greater than 70°C (158°F), including liquefied bitumen. Insulation boards of this type include fibreboard, polyisocyanurate and mineral wool. Note that heat-resistant does not mean or even infer 'fire-proof'. While some heat-resistant insulation materials will resist burning for a period of time, only mineral wool insulation will not burn.

See the Glossary for other terms used in this Section.

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1. A minimum slope of 1:6 (2" in 12") is required. Where the designed slope is less than 1:4 (3/12), the engineered shop drawing package must be accompanied by manufacturer’s literature confirming that this application is acceptable. Roofs with designed slopes less than the stated minimum (such as curved applications) will be considered for a RoofStar Guarantee provided

   • the design and installation details are submitted in writing to the Guarantee Program Administrator prior to the tendering of documents; and
   • a written Variance is issued by the RoofStar Guarantee Program prior to close of tender.

     See also Section 7 METAL PANELS.

2. Architectural metal roof panels that are installed on curved roof decks must be power-curved as a continuous panel, in line with the minimum radii and metal types published in the machine manual issued by the manufacturer of the panel-curving machine. Alternatively, if flat roll formed metal panels are installed on curved roof decks a panel stress calculation must be completed by a professional engineer prior to installation of metal panels.

3. If proprietary systems are specified, the manufacturer's suggested minimum slope and application procedures must be followed in addition to RoofStar Guarantee requirements

7.2 Tie-in (Re-roofing or Building Additions)

Where a new roof is tied-in to an existing roof, the two areas must be isolated and separated by a curb joint properly constructed a minimum height of 125 mm (5”), attached to the structure and properly flashed. If job conditions or aesthetic considerations do not allow for a curb joint, written permission must be obtained from the RoofStar Guarantee Program department to eliminate curb joints; a positive water cut-off must be installed to the deck to isolate the existing roof from the new roof.

7.3 Roof Decks

7.3.1 Wood Decks

1. All wood decks shall be properly nailed and cracks shall be covered with metal prior to acceptance of deck surface. This work is to be done by others.
2. Plywood with a minimum thickness of 15.9 mm (5/8") is the only acceptable sheathing to be used for wood roof decking, unless applied over a solid lumber decks. . Tongue and groove plywood sheathing, a minimum thickness of 15.9 mm (5/8"), is required for decking on all copper and zinc non-ferrous (i.e. copper, zinc) metal panel roof systems.
3. OSB (sheathing) is not acceptable.

7.3.2 Steel Decks

1. Steel decks must conform to one of the following specifications:

ASTM Standard Specification A653 / A653M, Sheet Steel, Zinc-Coated (Galvanized) by the Hot-Dip Process, Structural (Physical) Quality, minimum Grade 33, with a design thickness of 22 gauge (0.759 mm) or greater and a minimum zinc coating designation Z275.

ASTM Standard Specification A792 / A792M, Steel Sheet, Aluminium-Zinc Alloy-Coated by the Hot-Dip Process, General Requirements, minimum Grade 33, with a design thickness of 22 gauge (0.759 mm) or greater and a minimum aluminium-zinc alloy coating designation AZ150.

7.3.3 Concrete Decks or Walls

1. Direct contact between metal roofing and concrete, light concrete, stone and mortar must be avoided. The selection of a suitable underlay, insulation, and method of attachment to a concrete deck or wall is the responsibility of the design authority.

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8 AIR & VAPOUR BARRIERS, VENTILATION

8.1 Intent

Air and vapour barriers, along with thermal barriers, water resistive barriers and water-shedding surfaces, serve to separate the outside environment from the interior environments of a structure. Continuous air barriers are perhaps the most critical. Building Codes in force in each jurisdiction, and the National Energy Code (2011), require the selection and proper installation of “a continuous air barrier system comprised of air-barrier assemblies to control air leakage into and out of the conditioned space” (NEC 2011).

Continuity of the air and/or vapour barrier from the wall systems and roof systems is essential to the satisfactory performance of either or both. Therefore, proper connection between air and/or vapour barrier systems is essential, and the responsibility of both the design authority and trades constructing walls and roofs.

Air barriers control “flow of air through the building enclosure, either inward or outward” (Guide for Designing Energy Efficient Building Enclosures, Homeowner Protection Office). Controlling air flow into and out of conditioned spaces affects the performance of “thermally efficient enclosure assemblies” (ibid), impacts the potential for condensation in between materials, and directly influences rain water penetration of the building envelope. Some air barriers are considered permeable, others air-impermeable or ‘airtight’. The suitability of one over the other, in the application of a roofing system, is left to the discernment of the design authority and/or the roofing contractor. Consequently, the RoofStar Guarantee Program strongly recommends that designers and builders of roof systems intended to qualify for a RoofStar Guarantee carefully consider the regulatory design and installation requirements for effective, continuous air barrier systems.

Vapour barriers regulate or prohibit the movement of water vapour from one space to another by means of diffusion. Consequently, these barriers are referred to as either vapour-permeable or impermeable. Diffusion is a slow process, in contrast to air movement, and its regulation is not always mandatory or even desirable. Consequently, because continuous vapour barriers “are not needed within all climate zones and assemblies”, they are considered non-critical and may be left to the discretion of the design authority. Nevertheless, where continuous vapour barriers are required and specified by provincial or municipal building codes (current and in force), the RoofStar Guarantee Program requires that a suitable vapour barrier system be selected by the design authority and properly installed by the roofing contractor in conformity with the vapour barrier manufacturer’s published instructions, and with the design authority’s specified details.

Any references in this Manual to installation methodologies, and any construction details that show air and/or vapour barriers, are merely illustrative and not prescriptive. Installers of continuous air and/or vapour barrier systems are urged to understand and comply with best practices for their application.

8.2 Limitations and Exclusions

1. Air and vapour barrier performance is not part of the RoofStar Guarantee, and air/vapour barrier materials are not listed in the Accepted Materials section of this Manual. Therefore, the decision to specify an air and/or vapour barrier, the placement of a continuous air and/or vapour barrier in relation to a roof assembly and system, and the selection of suitable materials for that application, is the sole responsibility of the design authority.The design authority is urged to review and consider the performance characteristics of materials available for such applications.

   Neither the RoofStar Guarantee Program nor the roofing contractor will accept any responsibility for damage to, or failure of, the roof system caused by the use or absence of air and/or vapour barriers.

2. Proper installation and continuity of air and/or vapour barriers within the roof assembly is the responsibility of the roofing contractor. The air/vapour barrier must:

• extend past the roof membrane flashing by 100mm (4”) on new construction providing a positive (water-shedding) lap seal union between courses of material for the wall air/vapour barrier membrane applicator.
• be sealed to the wall air/vapour barrier on roof replacement projects.

Installation must conform to the manufacturer’s published requirements and the design authority’s design details.

8.3 Material Selection

1. Fully supported air and/or vapour barriers must possess a minimum published static puncture resistance rating of 150 N (34 lbf) (ref. CGSB-37.56-M for both test method and standard limits) and be either self-adhering or torch-applied. For unsupported air and/or vapour barriers, see 4.3.3 below. Therefore, while responsibility for the selection of a suitable air/vapour barrier rests with the design authority, a roof designed and built to qualify for a RoofStar Guarantee shall not include either polyethylene sheet plastic or bitumen-impregnated kraft paper.

2. Where air and/or vapour barriers are specified by the design authority, they must be selected from the materials listed in the wind-tested assemblies reports for MARS, PARS or AARS roof systems (excluding polyethylene sheet plastic and kraft paper, as noted above). For a complete listing of current wind test reports, click on the linked system acronyms above.

3. Notwithstanding any of the foregoing, the RoofStar Guarantee Program strongly recommends that any air and/or vapour barrier system be installed over a smooth, continuous plane (for example, concrete or plywood). Consequently, a deck overlay board installed on corrugated steel roof decks in highly recommended. Where no deck overlay board is installed and the air and/or vapour barrier is partially unsupported (for example, on a steel deck), the air and/or vapour barrier must have a published static puncture resistance of at least 400 N (90 lbf). Furthermore, both the side laps and end laps must be fully supported.

4. Should the air/vapour barrier membrane be used as a temporary roof during project construction by either the roofing contractor or by other trades, a minimum 2mm thick bituminous membrane is recommended.

5. Because curing concrete releases considerable moisture that can compromise the performance of a roof system, a vapour barrier installed on new concrete decks (28 days or older) must be selected to prevent condensation inside the roof system. A membrane with a permeability of 0.01 perms (Class I) is recommended. Nevertheless, the selection of the vapour barrier product is the responsibility of the design authority.

8.4 Vapour Retarder Design for High-Humidity Building Interiors

Careful consideration should be given to the performance characteristics of air and/or vapour barriers when specifying such a membrane for roof assemblies constructed over high-humidity building interiors. These types of building interiors include (but are not limited to)

• Swimming pools
• Commercial laundry facilities
• Large aquariums

• Paper mills

Roof systems for facilities such as these, with high-humidity environments, may be susceptible to the accumulation of moisture within the roof assembly unless an effective vapour barrier is specified and installed.

Vapour retarders for high humidity facilities should have a perm rating as close to zero as possible, be durable, multi-layer membranes that are effective in preventing vapour drive into the roof systems from the interior of high humidity environments.

Thin, lightweight, single-layer vapour retarders are prone to damage during installation of roof assemblies and are therefore not recommended for use over high humidity building interiors.

8.5 Ventilation

The attic or ceiling space should be adequately ventilated according to the BC Building Code standards (current edition). The design of roof ventilation is the responsibility of the design authority.

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9 EAVE PROTECTION, UNDERLAYMENT and DRAINAGE

9.1 Eave, Wall and Detail Protection

1. Ice and water eave protection is required for all RoofStar Guaranteed metal roofing systems. Eave protection must be a RoofStar-accepted self-adhered modified bituminous membrane. Eave protection must be carried a minimum of 600 mm (24") inside interior walls or 900 mm (36") in heavy snow load conditions.

2. For vertical transitions, the underlayment must extend beyond the furthermost edge of the flashing at least 100 mm (4") and positively lap beneath other vertical membranes.

3. Membrane protection for vertical penetrations (i.e. curbs) must extend 100 mm (4”) vertically and positively lap horizontal membranes by at least 150 mm (6”).

9.2 Underlayment

1. All roof assembly components installed above the structural deck must be installed by the member (roofing) contractor.

2. Only RoofStar-accepted underlayments may be used in metal roof systems, and must meet or exceed the National Building Code of Canada (current edition) for roofing underlayment.. All acceptable membranes must provide proprietary sealants, mastics, tapes and/or primers suitable for the application of the underlayment and must be applied in accordance with the manufacturer’s written instructions.

   Horizontal runs of underlayment must be positively lapped at least 50 mm (2") and end laps (vertical joints) must be at least 150 mm (6"). Where negative (backward) laps are unavoidable, only a RoofStar-accepted self-adhering underlayment may be used. Negative laps must be at least 150 mm (6"), and seams must be roller-pressed and sealed with a compatible mastic along the seam edge.

3. Minimum allowable thicknesses for a modified bituminous membrane underlayment is 1mm on slopes 2:12 and greater.

4. The location of the membrane is the responsibility of the design authority.

5. For slopes between 1:6 (2" in 12") and up to but not including 1:3 (4" in 12"), a continuous Accepted self-adhesive membrane underlay must be installed prior to the application of the sheet metal roofing. Direct torch application to wood surfaces is not permitted.

6. For slopes 1:3 (4" in 12") and greater, a RoofStar-accepted underlay for metal roofing is required. Accepted materials for this purpose are listed in the Eave Protection & Underlayment (Architectural Metal Roofing) section of this Manual.

7. Underlayment must be installed horizontally on slopes up to 8/12. On slopes steeper than 8/12, the underlayment must be self-adhering if installed vertically. Underlayment may be installed perpendicular to the eaves provided the laps are self-sealing or sealed with a suitable lap cement provided by the underlay manufacturer.

8. Back pan membrane protection must be 900 mm (36") wide. Membrane to be the same materials as used for eave protection.

9. RoofStar-accepted modified bituminous underlayments utilized directly beneath metal roof panels and flashings, or otherwise protected by insulating materials, must be made of bitumen with a high softening point and a minimum flow temperature of 87.7°C (190°F) ASTM D5147 high temperature stability.

10. Where a vapour-permeable membrane overlay is used over insulation for additional moisture protection, a minimum air space of 10 mm (3/8”) above the vapour-permeable membrane is mandatory. Regardless of the foregoing, the design authority is responsible to evaluate the necessity and determine the applicability of a second membrane above the insulation.

9.3 Slip Sheets and Drainage

1. A slip-sheet is required when metal panels or flashings come in direct contact with any asphaltic underlayments that do not have a tri-laminate facer, or if soldering is to be done.

2. For roofs designed with a slope less than 4/12, drainage beneath the metal panel must be facilitated with either

• A continuous layer of entangled mesh no less than 10 mm (3/8”) in thickness, or
• With clips incorporating tabs 3/8” above the top surface of clip base.

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10 INSULATION

10.1 General

1. Insulation is to be specified by the design authority. A list of acceptable insulation materials may be found in Roof Deck Insulation.

10.2 Material Selection

1. Insulation compressive strength must be taken into consideration by the structural engineer.

2. Only heat-resistant insulation may be used directly beneath metal panels or flashings.

10.3 Application

10.3.1 Layering

1. If the insulation assembly exceeds 67.5 mm (2.7”), it must be configured in multiple layers.

2. Insulation joints must be offset or staggered a minimum 300 mm (12") from adjacent layers and rows.

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11 FASTENERS

1. Clips must be proprietary (not shop fabricated) and must be acceptable to the roll form machine manufacturer, for use with the metal roofing systems.

   Unless otherwise specified by the design authority, clips must be attached by at least two fasteners and have evenly spaced indents or guide holes for fastener placement.

   Attachment clips for metal roofing systems must be formed from

   • Steel (Z275 or G90)(AZ50 or AZM150)
   • Aluminum

   • Stainless Steel

2. Concealed fasteners should provide clearance for the underside of the metal panel and must be of a material compatible with the metal clip.

3. Metal flashings must be attached with hidden metal cleats. On vertical applications with limited scope, or on neoprene or EPDM form-flashings with aluminum flanges, blind rivets may be used as an alternative method of flashing attachment. Rivets shall be closed-end, dome-head type. High-domed gasketed cladding screws are not acceptable for application in exposed locations.

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12 VALLEYS

1. Valley protection membrane must be at least 1000 mm (39") wide and centred on the valley. Membrane to be the same materials as used for eave protection.

2. Metal valley panels must be installed shingle fashion and must overlap the adjacent lower panel at least 200 mm (8"). Seal the lapped joint with two horizontal rows of approved caulking.

3. Metal valley drag load fastening is mandatory on all valleys.

4. Valley dividers are required and must be a minimum of 25 mm (1") high, folded to a maximum of 60 degrees on the inside angle of the divider.

5. Exposed valley widths must be a minimum 125 mm (5") from divider to metal roof panel on each side of the divider. Increased width is recommended in heavy snow load areas.

6. Unhooked metal valley sections must be returned 37 mm (1 1/2") to form a water cut-off, and must be secured with continuous cleats, fastened according to the specifications of the design engineer. Continuous cleats must be at least 26 Ga. and must be at least 76 mm (3”) wide and must be covered with at least a 300 mm (12”) approved self-adhered modified bituminous membrane sealed to the valley protection membrane (see Detail E1.7.6).

7. Hooked metal valley, metal roof panel overlaps must be one-piece with a built-in hook strip returned 37 mm (1 1/2") to form a water cut-off. Fastener spacing shall be determined by the design engineer, and must be covered with at least a 300 mm (12”) approved self-adhered modified bituminous membrane sealed to the valley protection membrane (see Detail E1.7.5).

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13 METAL PANELS

13.1 Materials

13.1.1 Material Acceptance

1. Materials and metal roofing systems to be covered by the RoofStar Guarantee Program must be listed in the Accepted Materials section of this Manual.

2. Member contractors must provide a mill certification for all metal roofing projects installed under the RoofStar Guarantee Program. Mill certifications must confirm that the sheet metal used for forming metal panels and flashings conform to or exceed one of the following standards:

   Sheet Steel Materials

   Aluminum-zinc alloy coated steel sheet, 0.6858 mm (0.027", 24 gauge) thick, conforming to ASTM A792 / A792M-06 SS Grade 33, AZM150 (AZ50) coating. Thickness tolerance as per ASTM A924 / A924M-06 ±0.08 mm (0.003") for sheet widths not exceeding 1500 mm (60"). Only PVDF coatings (polyvinylidene fluoride, also referred to as PVF2) may be used on Al-Zn steel stock acceptable for use in a RoofStar Guarantee.

   Galvanized steel sheet, 0.6858 mm (0.027", 24 gauge) thick, conforming to ASTM A653 / A653M-06 SS Grade 33, Z275 (G90) coating. Thickness tolerance as per ASTM A924 / A924M-06 ±0.08 mm (0.003") for sheet widths not exceeding 1500 mm (60"). Only PVDF coatings (polyvinylidene fluoride, also referred to as PVF2) may be used on G90 galvanized steel stock acceptable for use in a RoofStar Guarantee.

   Non-Ferrous Materials

   Copper sheet, 0.56 mm (.0216" 16 oz) thick, cold rolled roofing copper to ASTM B370-91. Maximum thickness tolerance ± 0.04 mm (0.0015)

   Zinc sheet, 0.81 mm (0.031") ± 0.03 mm thick, conforming to European Standard EN 988-1996. Zinc grade Z1 conforming to En 1179 that is 99.995% minimum zinc content, with addition of copper-titanium alloys. Maximum thickness tolerance variation ± 0.03 mm (0.0012").

3. Flat stock used for flashing fabrication on metal roofing systems must meet or exceed the grade and design thickness (gauge) of the metal roof panels.

13.1.2 Material Storage

1. All materials must be protected from weather by properly stacking above ground or roof surface. Elevate one end to promote drainage and block centre to prevent sagging. Protect panels against condensation between adjacent surfaces. Retain factory packaging or provide other adequate covering until material is applied. Handle panels with non-marring slings and use a spreader bar for hoisting. If site formed panels are specified, coils must be protected from condensation and stacked in an upright manner.

13.2 ROLL-FORMED PANELS

1. Metal roofing systems must be installed with clips and screws that are specified or listed as acceptable, by the metal panel machine manufacturer, for use with the metal roofing system.

2. Contractors and owners of metal panel machines are responsible to meet or exceed the panel machine maintenance standards as established by the roll form machine manufacturer.

3. All metal roof panels over 300 mm (12”) in width must be roll-formed with stiffening ribs or striations.

4. Sheet steel, copper and zinc roof panels may be roll-formed to a maximum width of 500 mm (20”) and panels must be installed with a continuous minimum tolerance gap of 1/8” between the heels of the panels.

13.2.1 Roll-forming Machines

1. Site-forming metal panel machines must be certified annually by a third party engineer. Machines must be serviceable, maintained and calibrated with supporting documentation. Records must be submitted to the RCABC annually.

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14 TESTING

14.1 Wind Uplift

The RoofStar Guarantee Program (RCABC Guarantee Corp., or RGC) initiated an investigation to establish the wind uplift resistance of architectural concealed fastener metal roof systems for use in British Columbia. The wind uplift tests were carried out at the Dynamic Roofing Facility at National Research Council, Institute For Research In Construction (NRC / IRC).

NRC / IRC report No.B1040 –3 (see ASM Special Applications) provides a simplified procedure for wind uplift design for roof assemblies with architectural metal roof coverings. In addition, NRC / IRC reports No. B1040-1 and B1040-2 provided the wind resistance test results for RoofStar-accepted metal panel systems and assisted the RoofStar Guarantee Program in developing guarantee standards and acceptance criteria for the Architectural Concealed Fastener Metal Roof Systems that are accepted for used in the RoofStar Guarantee Program.

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15 BUILT-IN GUTTERS

Built-in gutters (see also Detail E1.7.17) adjoining metal roofing systems are to be installed by RCABC member contractors in order to qualify for an RoofStar five (5) or ten (10) year guarantee.

1. Gutters shall be designed a minimum of 300 mm (12”) wide, and the depth shall not exceed the gutter’s width.

2. Only fully-adhered membranes may be used in built-in gutters, and only EPDM, PVC, TPO or 2-ply modified bituminous membranes are acceptable for this application. For single-ply membranes, the minimum thickness shall be 60 mils (1.524 mm). The fully-adhered membrane must be carried up the slope at least 150 mm (6”) beyond the maximum water level (further in regions with typical heavy snow). Where necessary, extend the gutter membrane as eave protection by overlapping the eave membrane at least 200 mm (8”) over the gutter membrane, in shingle fashion.

   Gutter membranes must be mechanically secured at their terminations, both on the outside of the gutter edge and on the slope beneath the metal panel system. Fasteners securing the membrane on the slope must be placed at least 150 mm (6”) above the maximum water level. Securement fastener spacing shall be no more than 300 mm (12”) O.C., but may be omitted where metal panel clips are fastened through the membrane with the same spacing.

3. All fasteners, and metal roof panels adjoining a built-in gutter, must be fastened a minimum of 100 mm (4") above the maximum water fill level.

4. Metal roof system underlay / eave protection must overlap built-in gutter membrane by a minimum of 200 mm (8").

5. Copper sheet with soldered seams and a RoofStar-accepted underlayment is acceptable for use as a built-in gutter liner material on copper standing seam metal roof systems.

6. Stainless steel sheet with welded seams and a RoofStar-accepted underlayment is acceptable for use as a built-in gutter liner material on zinc and copper standing seam metal roof systems.

7. A scupper overflow drain is mandatory.

8. Built in gutter membrane over insulation must transition onto underlayment membrane that is under insulation by use of sloped insulation and as detailed in construction drawing E1.7.16 Built-in Gutter. The opposing tapered insulation must be separated from the membrane by entangled mesh. The gutter membrane must lap with the underlayment at least 200 mm (8”) above the back edge of the insulation wedge.

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16 MANSARDS

1. Mansards are considered part of the roof assembly. For applications of metal roofing to mansards follow the same RoofStar Guarantee Standards listed in this Section.

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17 SNOWGUARDS AND HIGH SNOW LOAD AREAS

1. Snowguards are not part of the roof assembly, but must not penetrate the metal roof assembly and must be designed in consultation with the structural engineer for the metal roofing system. The decision to use, and / or the selection of snowguards, is the responsibility of the design authority. Neither the RoofStar Guarantee Program nor the roofing contractor will accept any responsibility for damage to, or failure of, the roof system caused by the use or absence of snowguards.

2. The design authority is advised to consult with the manufacturer and the roofing contractor when building in areas considered by Environment Canada as high snow load areas (For RoofStar Guarantee purposes, high snow load is considered regional areas with snow loading higher than 3.5 kPa as referenced in the National Building Code Appendix C “Climatic Information for Building Design in Canada”). Consideration should be given to: slope, entrances / exits, penetrations, and the proximity of adjacent structures.

   Consideration should be given to:

   • slope
   • entrances/exits
   • penetrations, and
   • the proximity of adjacent structures.

3. For roofs subject to high snow loads, a solid substrate, a minimum slope of 1:1.5 (8"/12"), the use of an Accepted self-adhered modified bituminous membranes as eave protection, and underlay are required (see Accepted Materials).

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18 CAULKING

1. Caulking shall be non-hardening, suitable for exterior use, high quality butyl or polyurethane sealant in either gun grade or sealant tape form. Two rows of caulking are required for all metal valley and metal flashing overlaps.

2. Caulking shall conform to any one of the following:

.1 CGSB 19-GP-5M, “Sealing Compound, One Component, Acrylic Base, Solvent Curing”;

.2 CAN / CGSB-19.13, “Sealing Compound, One Component, Elastomeric, Chemical Curing”;

.3 CGSB 19-GP-14M, “Sealing Compound, One Component, Butyl-Polyisobutylene Polymer Base, Solvent Curing”; or

.4 CAN / CGSB-19.24, “Multi-Component, Chemical Curing Sealing Compound”.

Caulking shall be selected for its ability to resist the effects of weathering. Caulking must be compatible with and adhere to the material which it is applied to.

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19 INSTALLATION DETAILS

19.1 Curbs

1. The design and placement of curbs, for skylights or penetrations, shall be the responsibility of the design engineer. Curbs must be constructed to achieve a minimum height of 200 mm (8”) above the finished roof surface. For underlayment requirements, see 3.2 Eave, Wall and Detail Protection.

2. All curbs shall be constructed on a split pan and affixed to the pan with blind rivets. See Section 5 FASTENERS for requirements. Mechanically affix to the roof deck cleats fashioned from compatible metal (min. 24 Ga. – see material requirements above), and hook the split pan and adjacent roof panels to the cleats in shingle-fashion, with positive laps. Each lap shall be sealed with two parallel un-tooled beads/rows of an acceptable caulking (see Section 12 CAULKING).

3. Curbs smaller than 900 mm (36”) in width (with no height limitations) may be designed with a cricket but require, as a minimum, a back-pan flashing. Back-pan flashings must extend past the edges of the curb by 100 mm (4”), but project no closer to the adjacent seam than 51 mm (2”). For reference, see detail (TBA).

4. Curbs wider than 900 mm (36”) and taller than 200 mm (8”) from the finished roof surface require an architectural metal cricket to divert snow load. Cricket metal must be integrated with the curb flashing panels. Cricket metal flanges must be lapped beneath the metal curb flashing at least 51 mm (2”). Any seams in the cricket design and construction must be either welded or sealed with two beads/rows of an acceptable caulking and riveted with blind rivets.

5. Crickets wider than 900 mm (36”) in width (450 mm from the center) require supportive backing to prevent cricket metal distortion.

6. Overlapping metal pans must be sealed with two rows of accepted sealant. Preformed closures are required for trapezoidal ribbed roof panels.

7. Curbs wider than 2400 mm (8’) must incorporate a built-in gutter along the top and sides of the curb (see Section 9 BUILT-IN GUTTERS, above). Curbs in this category must incorporate a structural diverter, designed to direct water and snow to either side of the curb. Lap continuous gutter membrane onto sloped insulation installed on either side of the curb, and lap gutter membrane over split-pan at the down-slope side of the curb. Install metal curb flashing following the standards for curbs set out PERIMETER FLASHING: Metal under any of the low-slope membrane systems. Adjoin down-slope gutter to metal roof system with a split-pan connector, and lap the gutter membrane onto the split-pan no less than 150 mm (6”). Split pan and metal panels must be hooked together with hidden cleats.

19.2 Penetrations

1. Metal roof panel penetrations, e.g. plumbing, venting, flashings, etc., must have a minimum 300 mm (12") clearance from all other roof projections to permit proper flashing (see Detail E1.7.8 and Detail E1.7.9).

2. Metal roof flexible pipe penetration flashings must be located so as not to interfere with standing seams or panel ribs. If interference is unavoidable, see [detail TBA].

3. Any penetrations larger in diameter than 150 mm (6”), and all exhaust flues (B-vents), must be installed on curbs (see above).

19.3 Perimeter Edge Securement

1. Metal panels must be secured at the eaves by a continuous metal hook strip (see Detail E1.7.3).

2. Gable and roof-to-wall flashings must be engineer-designed to withstand wind uplift, allow for expansion and contraction, and must not utilize exposed fasteners.

19.4 Metal Cap/Hip Flashing

1. For roof slopes up to 8/12, metal cap / hip flashing must extend a minimum of 150 mm (6") over metal roof panels, measured from the back pan, and extending on each side of the ridge / hip.

2. For roof slopes equal to or greater than 8/12, the metal cap/hip flashing may be reduced by 75mm (3”) over metal roof panels, measured from the back pan and extending on each side of the ridge/hip.

3. For roof slopes greater than 12/12, an underlying support at the centre of the ridge is required to support the ridge cap flashing.

4. Standard cap / hip flashing must be hooked to metal Z closures which are set in sealant tape and fastened through the metal roof panel into the deck.

19.5 Weather Stops

1. Two panel weather stops must be installed at up-slope terminations.

2. The up-slope termination of metal panels must be turned up (bread-panned) to a height of at least 26 mm (1”), and shall in any event be equal in height to the top of seamed ribs. Turned up corners (dog ears) are not to be cut.

3. Metal Z-closures must be sealed weather tight with caulking and/or sealant tape.

4. The second weather stop may include any of the following:

   • metal Z-closures, or

   • metal flashings turned down between panel ribs to close off openings.

19.6 Low Slope Tie-in

1. Metal roof panels adjoining a low slope roof must terminate 200 mm (8") up the slope from the roof surfacing.

2. Metal roof system underlay / eave protection must overlap low slope roof membrane flashing by a minimum of 100 mm (4").

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ASM Roof Systems

Accepted Materials