Template:Part 9 (Waterproofing Roofs - SBS)

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Template:Part 9 (Waterproofing Roofs - SBS)

See more information on Waterproofing Materials in Division B: Essential Elements.


1 General

SBS-modified bituminous membranes are normally designed for application only on Flat or Low Slope structural roof decks and come in a variety of thicknesses and surface finishes, may be reinforced with different materials (each reinforcement material exhibiting particular properties and offering different benefits), and may each be applied in one or more ways.

Most SBS-modified bituminous membranes are designed as two separate plies – a base and cap membrane – which are heat-welded together as a 2-ply assembly. Some are self-adhered or adhered to each other and to a substrate with mop-applied hot bitumen or with an adhesive (see below). A third ply is occasionally part of the manufacturer's specified system and may be required or simply is prudent for additional waterproofing protection in certain circumstances.

Common applications include:

  1. Mechanically fastened (where the base membrane is affixed to the roof deck with self-drilling screws and load-distributing plates; the cap membrane is then torch-applied or adhered to the base).
  2. Torch-applied (where torch heat brought to bear on the both the base and cap membranes liquefies the modified bitumen in the membrane so that it bonds with the substrate below).
  3. Adhered:
    1. Self-adhering (SA) (using a proprietary adhesive film bonded to the modified bitumen, SA membranes are often adhered with the help of a primer; occasionally, the base membrane is self-adhering, and the cap membrane is then torch-applied to the base).
    2. Cold-adhered (using bitumen-based or synthetic adhesive, this may sometimes be referred to as 'cold-applied’).
    3. Hot bitumen adhered (sometimes referred to as 'hot-mopped', 'hot-applied' or simply 'mopped', this application method applies to both the base and cap membranes, or may apply only to the base membrane; the cap, then, is torch-applied to the base membrane).

1.1 Design

1.1.1 RoofStar 15-Year Guarantee

  1. Refer to 1.3.1 RoofStar 15-Year Guarantee for general requirements, to qualify the Project for a RoofStar 15-year Guarantee.
  2. See Table 9.2 for membranes and application types that qualify for a RoofStar 15-Year Guarantee.

1.1.2 All Projects

  1. All membrane-type Waterproofing Systems (together with the supporting deck structure they are designed for) shall meet the requirements of the British Columbia Building Code and the RoofStar Guarantee Standards, and shall be (when applicable)
    1. a Tested Assembly.
    2. an Assembly with Proven Past Performance.
    3. an assembly with custom-engineered securement.

    See also Part 3 SECURING the ROOF ASSEMBLY.
  2. The specifications, details, and installation techniques must conform to the membrane manufacturer's requirements.
  3. Select a membrane for its
    1. composition, both in terms of thickness and reinforcement.
    2. performance characteristics in relation to the intended use of the roof, as for example puncture resistance or reflectivity and reduced heat absorption.
    3. application methodology, which may be limited by the type of supporting deck or substrate to which it will be applied.
    4. seasonal applications (summer and winter grades).
  4. When the designed slope of the roof exceeds 1:6 (2” in 12”), and either or both membranes are self-adhered, the head-lap of a full or partial membrane run, installed parallel to the slope, must be secured with at least three (3) mechanical fasteners and plates equally spaced across its width. When the membrane is specified to run perpendicular to the slope, the up-slope seam must be mechanically fastened with screws and plates no more than 600 mm (24”) O.C.
  5. A nailed base membrane, to which a cap membrane is torch-applied, does not qualify as part of a 2-ply membrane. Only base membranes designed for in-seam screw-type fasteners and covered with a fully torch-applied cap membrane may qualify.
  6. Primary roof membranes may not be directly adhered to a wood deck.
  7. When a roof system installed on a concrete deck or concrete topping is uninsulated, the base membrane must be vented in order to mitigate the effects of vapour drive from the concrete.
  8. When the roof slope exceeds 1:24 (1/2” in 12”), only cap membranes installed by methods other than with hot bitumen may be specified.
  9. Any roof areas less than 1:16 (¾" in 12") require 2 ply membrane assemblies. Single-ply SBS-modified bituminous membranes may be used only when the roof slope is greater than 1:16 (¾” in 12”), and may be adhered, self-adhered, mechanically fastened, or torch-applied to the substrate for which they are designed and specified. See 9.3 Application below for specific RoofStar Guarantee requirements for single-ply SBS-modified bituminous membranes.
  10. Installed membranes must be protected from damage caused by work performed concurrently or subsequently by other trades. The Design Authority is strongly urged to direct the work of other trades through specific, explicit directives in the design specifications.
  11. Membranes must be protected from chemicals or other contaminants that may adversely impact the roof membrane or other system components (for example, specifying a grease guard or a reinforced 2-part liquid membrane coating). Consult the membrane manufacturer for their advice and recommendations. Contaminants may include, without limitation,
    1. animal or vegetable grease.
    2. hot pipes (release valves).
    3. petroleum products or biproducts.
    4. miscellaneous fluids from equipment, detrimental to the membrane.

    See also 9.2.1 (Materials) and 9.3.6 (Application). Also refer to 11.3.3.3 for application of reinforced liquid membrane flashing around roof penetrations.
  12. Membranes should be protected from the following contaminants:
    1. pool or garden chemicals and fertilizers.
    2. pet urine.
    3. bird excrement.
    4. refrigerants.
  13. When a conventionally insulated roof will be accessed at least once per month for maintenance of serviceable equipment, the design must incorporate designated walkways to protect the primary membrane at roof access points, equipment service locations and along travel routes.
  14. Where walkways are employed, they must be designed to facilitate drainage of water. Pedestals and other paver supports provide airflow for drying surfaces and assist in leveling. While pavers must be designed for securement against movement by wind, they should not impede the flow of water or air and should uniformly distribute the dead load of pavers and predicted live loads. The Design Authority may specify
    1. RoofStar-accepted concrete topped XPS insulation panels.
    2. pavers placed on
      1. purpose-made pedestals and rubber pads (slip sheets under pedestals may be necessary to prevent membrane abrasion).
      2. drainage mats.
      3. XPS insulation panels with drainage grooves or channels.
    3. proprietary walkway membranes installed in segments.
    4. proprietary coatings or a RoofStar-accepted 2-part liquid membranes applied over the field membrane (see 9.3.6).

      See also 1.6 RoofStar Guarantee: Coverage and Limitations
  15. Only PARS and AARS assemblies are permitted when a Conventionally Insulated System, or a portion of it, is designed to support any type of load; pavers supported by pedestals are an exception. This is subject to the limitations and standards in 14.1.2 Design.
  16. Only fully adhered membranes may be used in a Protected Membrane Roof System; mechanically attached membranes are not suitable and shall not be used for this application.
  17. Fall protection warning zones (see WorkSafeBC Regulations and related materials) may be designed using
    1. primary roof membranes in contrasting colours.
    2. a "sacrificial" third ply installed over the primary cap membrane.
    3. a proprietary coating.
  18. A sacrificial third ply is not part of the roof system and therefore is specifically excluded from coverage under a RoofStar Guarantee. See also 1.6 RoofStar Guarantee: Coverage and Limitations.

2 Materials

See Accepted SBS-Modified Bituminous Membranes for RoofStar Guaranteed roof systems. See also Part 3 SECURING the ROOF ASSEMBLY for special requirements concerning membrane roof Waterproofing Systems.

2.1 Composition, Thickness and Selection

  1. Both the base and cap membranes in 2 or 3-Ply SBS-modified bituminous membrane system must be modified with the same polymer. For example, if the cap membrane is modified with SBS, then the base membrane must be SBS-modified also. Oxidized asphalt membranes will be considered as underlay only and must not be counted as one of two plies.
  2. Membranes must be selected from the list of Accepted Materials published in this Manual, and each membrane must conform the minimum requirements outlined in Table 9.1 and Table 9.2
  3. Liquid membranes must be reinforced and accepted for use over a base membrane ply acceptable to the manufacturer of the liquid membrane.
  4. Some membranes may be susceptible to damage from bird droppings, pet urine or chemical contamination (oils, solvents or any discharge from a mechanical unit). The Design Authority is strongly urged to consider these issues in light of the overall Project design, consult with the membrane manufacturer for guidance, and provide adequate membrane protection when it is necessary. See also 14 Roof Coverings and Living Spaces.
Table 9.1 SBS-modified Bituminous Membranes: RoofStar 5 and 10-Year Guarantee
All thicknesses shown are in mm; Puncture Resistance measured in Newtons (N)
Conventionally Insulated or Uninsulated Waterproofing Systems (Roofs) PMRA Roofs
and
Grade-level
Waterproofing
Field and Membrane Flashing Vegetated
Assemblies
Single-Ply SBS
Cap Membranes
for Slopes
> 3/4:12
Field and Membrane
Flashing
Membrane Type, Reinforcement & Grade Mechanically
Fastened
(mm)
Adhesive
Applied
(mm)
Self-
Adhered
(mm)
Torch-
Applied
(mm)
Thickness
(mm)
Puncture
Resistance
(N)
Thickness
(mm)
Puncture
Resistance
(N)
Thickness
(mm)
Puncture
Resistance
(N)
Base Sheet (fibreglass) - Grade 3 2.3 2.2 2.3 2.3 N/A N/A N/A N/A 3.0 N/A
Base Sheet (polyester) - Grade 3 2.5 2.2 2.5 2.5 3.5 400 N/A N/A 3.0 N/A
Base Sheet (composite) - Grade 3 2.3 2.2 2.3 2.3 3.5 400 N/A N/A 3.0 N/A
Film Cap Sheet (fibreglass) - Grade 2 N/A 3.3 3.3 4.0 N/A N/A N/A N/A N/A N/A
Film Cap Sheet (polyester) - Grade 2 N/A 3.5 3.5 4.0 4.0 400 4.0 400 3.0 400
Film Cap Sheet (composite) - Grade 2 N/A 3.3 3.3 4.0 4.0 400 4.0 400 3.0 400
Granular Cap Sheet (fibreglass) - Grade 1 N/A 3.3 3.3 4.0 N/A N/A N/A N/A N/A N/A
Granular Cap Sheet (polyester) - Grade 1 N/A 3.5 3.5 4.0 4.0 400 4.0 400 3.0 400
Granular Cap Sheet (composite) - Grade 1 N/A 3.3 3.3 4.0 4.0 400 4.0 400 3.0 400
Table 9.2 SBS-modified Bituminous Membranes: RoofStar 15-Year Guarantee
All thicknesses shown are in mm; Puncture Resistance measured in Newtons (N)
Conventionally Insulated or Uninsulated Waterproofing Systems (Roofs) PMRA Roofs
and
Grade-level
Waterproofing
Field and Membrane Flashing Vegetated
Assemblies
Single-Ply SBS
Cap Membranes
for Slopes
> 3/4:12
Field and Membrane
Flashing
Membrane Type, Reinforcement & Grade Mechanically
Fastened
(mm)
Adhesive
Applied
(mm)
Self-
Adhered
(mm)
Torch-
Applied
(mm)
Thickness
(mm)
Puncture
Resistance
(N)
Thickness
(mm)
Puncture
Resistance
(N)
Thickness
(mm)
Puncture
Resistance
(N)
Base Sheet (fibreglass) - Grade 3 N/A N/A N/A N/A N/A N/A N/A N/A 3.0 N/A
Base Sheet (polyester) - Grade 3 N/A 2.5 2.5 2.5 3.5 400 N/A N/A 3.0 N/A
Base Sheet (composite) - Grade 3 N/A 2.5 2.5 2.5 3.5 400 N/A N/A 3.0 N/A
Film Cap Sheet (fibreglass) - Grade 2 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A
Film Cap Sheet (polyester) - Grade 2 N/A 4.0 4.0 4.0 4.0 400 3.0 400 3.0 400
Film Cap Sheet (composite) - Grade 2 N/A 4.0 4.0 4.0 4.0 400 4.0 400 3.0 400
Granular Cap Sheet (fibreglass) - Grade 1 N/A 4.0 4.0 4.0 N/A N/A N/A N/A N/A N/A
Granular Cap Sheet (polyester) - Grade 1 N/A 4.0 4.0 4.0 4.0 400 4.0 400 3.0 400
Granular Cap Sheet (composite) - Grade 1 N/A 4.0 4.0 4.0 4.0 400 4.0 400 3.0 400

2.2 Fasteners and Adhesives

See 3.2.3 Fasteners and Adhesives for attachment requirements.

2.3 Accessories

  1. All materials, including but not limited to primers, mastics, granules or coatings, that comprise the roof system must be supplied or accepted by the membrane manufacturer.

3 Application

3.1 General

3.1.1 RoofStar 15-Year Guarantee

  1. Refer to 1.3.1 RoofStar 15-Year Guarantee for general requirements, to qualify the Project for a RoofStar 15-year Guarantee.

3.1.2 All Projects

  1. Membranes must be installed according to the manufacturer's published instructions, details and installation techniques. Regardless of the instructions, the following standards prevail:
    1. All membrane openings at eaves, walls, vents, etc. must be sealed during application to prevent moisture from entering roofing or between plies of stripping.
    2. Except for the application of picture-framing techniques (see below under 10.3.3 Alternative Approaches to Membrane Flashing), both the base and cap membranes must be installed in a parallel direction (not perpendicular to each other).
    3. Both the base and cap membranes of a 2-ply un-granulated membrane assembly must be installed separately. Installation "shingle fashion" (i.e., 50% lap) is not acceptable except where membrane "back nailing" is required.
    4. Membranes should be installed beginning at the lowest point of the roof.
    5. When the designed slope of the roof
      1. exceeds 1:6 (2” in 12”) but is no greater than 1:3 (4” in 12”), and either or both membranes are self-adhered, the head-lap of a full or partial membrane run, installed parallel to the slope, must be secured with at least three (3) screw fasteners and plates equally spaced across its width.
      2. exceeds 1:3 (4” in 12”), and either or both membranes are self-adhered, the head-lap of a full or partial membrane run, installed parallel to the slope, must be secured with at least three (3) screw fasteners and plates equally spaced across its width. In addition, the side laps must be mechanically fastened with screws and plates spaced no more than 600 mm (24”) O.C.


      Membrane laps for either case must conform to the Standards published elsewhere in this Part.

    6. When the membrane is specified to run parallel to the slope, the up-slope seam must be mechanically fastened with screws and plates no more than 600 mm (24”) O.C.
    7. The installation of self-adhering membranes across the slope of the roof is not recommended.
    8. When a roof system installed on a concrete deck or concrete topping is uninsulated, the base membrane must be vented in order to mitigate the effects of vapour drive from the concrete.
    9. All membranes must
      1. overlap adjacent membranes (side laps) at least 75 mm (3”).
      2. overlap the end of the next membrane run at least 150 mm (6") - angle-cut the selvedge corner of the underlying membrane as required by the membrane manufacturer.
      3. be offset from adjacent membrane end laps by at least 300 mm (12”.
      4. be installed so that cap membrane end laps are located at least 900 mm (36”) from the centre of any roof field drain, except where drain sumps are employed.
    10. When membranes are mechanically fastened, side laps must be at least 100 mm (4”) and cover the fastener plate by at least 50 mm (2”).
    11. Ensure seams are fully bonded, both along the sides and at the ends of membrane runs:
      1. All base membrane field seams, regardless of the type of application, must be “buttered” before the end of the working day.
      2. All cap membranes must exhibit continuous visible bitumen bleed-out along seam edges.
      3. Cap membrane runs must be offset from the base field membrane seams, according to the membrane manufacturer's published instructions, and centred over drains.
    12. Single ply modified bituminous membranes
      1. must comply with the requirements listed in Table 9.1 and Table 9.2 (see 9.2.1 Composition, Thickness and Selection).
      2. require a minimum slope of 1:16 (3/4” in 12”).
  2. Any roof areas less than 1:16 (¾" in 12") require 2 ply membrane assemblies.
  3. At roof slope transitions where slopes less than 1:16 (¾" in 12") intersect a Water-shedding System, the Waterproofing System must be designed to extend up the Water-shedding System slope as described in 10.3.5.4 Transitions with Water-shedding Systems. Flash the transition in keeping with the Standards found elsewhere in this Part.
  4. Installation during cold weather must follow the membrane manufacturer’s guidelines for storage and membrane conditioning.
  5. At the end of a day, or when installation must be stopped because of circumstance (such as inclement weather), the base membrane of a Conventionally Insulated System must be temporarily and continuously sealed to envelope the insulation and other components enclosed below the 2-ply membrane system. Care must be taken to seal all possible points by which water might enter the new roof assembly.
  6. All installed membranes must be protected from splashed or dripped primer used to enhance adhesion of self-adhering membranes, as the primer may damage the membranes and cause leaks. This standard also applies to work by other trades, who may use primers for self-adhering membranes typically installed on walls or around doors, windows or other wall penetrations.

3.2 Materials Storage and Handling

  1. All uninstalled materials must be
    1. protected from weather.
    2. stacked above ground or the roof surface in packaging provided.
    3. approved or recommended by the manufacturer.

3.3 Mechanically Attached Membranes

  1. Whenever possible, orient mechanically fastened membranes perpendicular to steel deck flutes in order to distribute fasteners across the deck.
  2. To secure the membrane, use fasteners and stress plates that are
    1. specifically designed for the application of the specified and installed membrane, or are
    2. listed in the Tested Assembly report as an acceptable alternative (Substitutions, without the written consent of the primary membrane manufacturer, are not permitted and may void the RoofStar Guarantee).
  3. Unless otherwise listed in the assembly components of a Tested Assembly, membranes shall be fastened with self-drilling purpose-made #14 screws having a deep-recessed head.
  4. Single-ply modified bituminous membranes
    1. must comply with the requirements listed in Table 9.1 and Table 9.2 (see 9.2.1 Composition, Thickness and Selection).
    2. require a minimum slope 1:16 (¾" in 12").

3.4 Torch-applied Membranes

  1. Directly torch-applying any membrane to an unprotected combustible material is strictly prohibited.
  2. Torch-applied membranes must be applied to a suitable substrate (primed if required by the membrane manufacturer).
  3. Ensure that the membrane is fully and evenly bonded to the substrate. As the roll is installed, the roofer must
    1. sufficiently pre-heat the side lap of the preceding roll.
    2. burn off any film used to protect the uninstalled membrane surface.
    3. ensure sufficient heat melts the bottom layer of bitumen across the full width of the roll, to adequately bond the membrane to the substrate (A small "wave" or "bead" of melted bitumen in front of the roll usually indicates sufficient heat).
    4. Membrane end lap corners must be cut on a bias (clipped or trimmed on an angle) prior to forming end laps on all torch-applied modified bituminous membrane roof assemblies.
    5. Embed granules prior to forming end laps on all torch-applied modified bituminous cap membranes.
  4. The applicator must not over-torch or over-heat membranes. The polyester fabric used as reinforcement in many thermofusible "torch-on" membranes is subject to dimensional changes at high temperatures.
  5. Install cap membranes as soon as possible after base membrane installation. Installed base membranes must be protected from dirt, debris and damage; any damage sustained by the installed base membrane must be adequately repaired following the procedures recommended by the membrane manufacturer. This work is the responsibility of the Contractor.

3.5 Adhered Membranes

3.5.1 General

  1. Membranes may be
    1. self-adhering, typically requiring a primer to enhance adhesion (refer to the manufacturer's published instructions).
    2. adhered with
      1. cold adhesives (synthetic or bitumen-based).
      2. mop-applied hot bitumen (bitumen that is melted in a kettle).

    Different RoofStar Guarantee Standards apply to each of these, depending on the membrane type, the method of application and the slope of the roof.
  2. SBS-modified bituminous membranes shall not be fully adhered directly to a supporting wood deck structure. Rather,
    1. overlay the wood deck with a RoofStar-accepted deck overlay board, to which the membrane may be adhered.
    2. semi-adhere a vented base membrane to the wood deck.
    3. substitute a fully adhered membrane system with a mechanically attached membrane.

3.5.2 Self-adhered and Cold Adhesive-applied Membranes

  1. When both the base and cap membranes are self-adhered, the cap membrane must be installed on a clean, dry base and both must be completed together on the same workday, according to the manufacturer’s published instructions. Phased installation of membranes is not permitted.
  2. To ensure even, full contact with the substrate, all self-adhered and cold adhesive-applied field membranes must be fully rolled with a roller weighing at least 34.2 Kg (75 lbs).
  3. Self-adhesive membranes must be installed only when the ambient air temperature meets or exceeds the temperature permitted by the manufacturer.

3.5.3 Hot Bitumen-adhered Membranes

  1. All concrete decks to receive adhered membranes shall be primed with the membrane manufacturer’s asphaltic primer.
  2. Bitumen Temperatures
    1. The asphalt temperature must be at least 205°C (400°F) in order to fuse with the membrane.
    2. Asphalt should be mopped no more than 1 m (3') ahead of the roll.
    3. Rates may vary depending upon the substrate, and therefore the rates must follow the manufacturer’s published instructions.
  3. Install membranes with Type 3 or 4 oxidized asphalt or Type 3 or 4 SEBS modified asphalt.

3.6 Liquid Membranes

Where it is desirable for the field membrane to resist the damaging effects of grease, oils or other contaminants only an Accepted reinforced 2-component catalyzed polymethyl methacrylate (PMMA) liquid membrane may be specified and installed over a suitable base membrane. The following standards pertain to the application of these materials in the field and around penetrations:

  1. Use only liquid flashing membranes that are compatible with the primary base membrane.
  2. Ensure proper preparation of the base membrane, which must be clean, dry, free of contaminants and suitable to the liquid membrane manufacturer. Preparation must follow the procedures published by the liquid membrane manufacturer.
  3. Liquid membranes must be applied with clean, straight, plumb edges. Therefore, mask the boundaries of areas to which liquid membrane will be applied, ensuring adequate coverage on all surfaces.
  4. For all applications,
    1. apply a base layer of catalyzed liquid membrane resin within the area masked for coverage.
    2. reinforce the base coating with the manufacturer’s fleece and cut it to size so that the fleece is set in from the masked area no more than 3 mm (1/8”).
    3. ensure the fleece is fully saturated with liquid, following the published instructions from the manufacturer.
    4. coat the fleece with a second application of catalyzed liquid membrane resin, covering the masked area.
    5. coat the second application with a wearing coat, as specified by the manufacturer.
  5. When a granule surface or textured finish is specified, the granules or texturing material must be broadcast into a third coat.
  6. When applied to the roof field around a penetration, the same liquid membrane must extend up the adjacent vertical surfaces by at least 200 mm (8”). See also 11.3.3.3 Liquid Membrane Flashing. Application rates and guidelines issued by the manufacturer of the liquid flashing product must be followed, unless superseded by these Standards.

3.7 Membrane Walkways and Warning Zones

See also Part 14 The ROOF as a PLATFORM for design, material and installation requirements when using elevated pavers or other walkway materials.

  1. When pavers are used as the walkway material they must be
    1. spaced no closer than 3mm (1/8″)
    2. supported by non-abrasive pads or proprietary pedestals providing a minimum of 12.7 mm (1/2″) of vertical separation layer for airflow and leveling (slip sheets under pedestals may be necessary to prevent membrane abrasion).
    3. secured against movement by wind.
  2. When an additional membrane ply is installed over the Finished Waterproofing System, to serve as a ‘sacrificial’ walking surface, the third ply is not considered part of the roof system and therefore is excluded from coverage under the RoofStar Guarantee.
  3. When warning zones are specified as part of the primary roof membrane,
    1. the membrane
      1. may be part of the primary roof membrane, in a contrasting colour.
      2. must be oriented parallel to the primary field runs.
    2. staggered end laps must be maintained but must be located under the contrasting membrane in order to create a clean edge.