Grade-level Waterproofing Standard
Grade-level Waterproofing Standard
- 1 ABOUT WATERPROOFING
- 2 GENERAL REQUIREMENTS
- 3 DECKS
- 3.1 Deck Types
- 3.2 Expansion Joints
- 3.3 Tying Into Existing Waterproofing
- 4 MATERIALS
- 5 SUBSTRATES: Walls and Planters
- 6 MEMBRANES
- 7 PERIMETER FLASHING: Membranes
- 8 MEMBRANE PROTECTION
- 9 INSULATION
- 10 DRAINAGE
- 11 WEARING COURSE and OVERBURDEN
- 12 MEMBRANE MOISTURE SURVEYS & MONITORING SENSOR GRIDS
- 13 LANDSCAPING, PLANTERS & OTHER VEGETATED OVERBURDENS
- 13.1 General
- 13.2 Membrane Protection
- 13.3 Planter Design & Waterproofing
- 13.4 CSA A123.24 and Wind Uplift
- 13.5 Flood Testing
- 13.6 Overburdens
- 13.7 Walkways
- 14 PENETRATIONS and DRAINS
- 15 PERIMETER FLASHING: Metal
Division B - Standards
Standard for Grade-level Waterproofing Systems
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
- Reference materials
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For definitions of these terms of reference, click here.
1 ABOUT WATERPROOFING
1.1 Waterproofing versus Dampproofing
The definition of waterproofing is the treatment of surfaces or structures in order to prevent the passage of water under hydrostatic pressure. In contrast dampproofing is defined as the treatment of surfaces or structures to resist the passage of water in the absence of hydrostatic pressure. The hydrostatic pressure exerted by water lying against a barrier increases steadily in pressure as the depth of water increases. Water exerts a pressure of 1000kg per meter squared per meter of depth or 62.2 pounds per square foot per foot of depth. Standing water is often present on plaza decks which are typically horizontal low-sloped suspended structural decks over occupied spaces, subsequently this makes waterproofing and protected roofing systems, not dampproofing, the only reliable options to prevent the passage of water into structures.
1.2 Comparisons: Waterproofing, Conventional & Protected Membrane Roof Systems
The differences between waterproofing and low slope protected roofing membrane systems can be very subtle with many manufacturers' membranes often being interchangeable for both roofing as well as waterproofing applications on plaza decks. The two main features differentiating protected membrane roofing systems from waterproofing systems are the membrane flashing application techniques used at construction details and the type of wearing and or protection course used over the membrane assemblies. In contrast conventional roof systems are typically installed over insulations with the primary roof membrane exposed to weather or protected by light aggregates or coatings (for additional technical information refer to the Protected and Modified Protected Membranes part of these Guarantee Standards, or to Protected and Modified Protected Roof Systems in Section B: Essential Elements).
2 GENERAL REQUIREMENTS
The information provided in this section of the RCABC Roofing Practices Manual (RPM) contains standards to follow for RoofStar Guarantee coverage. It also includes technical information and recommendations to assist designers and applicators with waterproofing membrane applications on plazas, promenades and terraces. The formulation of the content of this section of the RPM is based upon the advice of, and information from, architects, manufacturers as well as the experiences of RCABC member professional roofing and waterproofing contractors.
RoofStar Guarantee Standards for Waterproofing are applicable to Plazas / Promenades and Terraces only. Vehicle parking structures, below grade walls, foundations, and repairs or renovations to existing waterproofing systems do not qualify for RoofStar Guarantee coverage. In addition, all waterproofing system components, including but not limited to membrane protection materials, drainage layers, overburdens including wearing course materials, must comply with and be installed to RoofStar Guarantee Standards set out below in this Section, in order to qualify for RoofStar Guarantee coverage.
2.1 Deck Slopes
A minimum slope of 1:50 (l/4" in 12") is strongly recommended for waterproofing systems, but positive slope to drain is an absolute requirement. To take advantage of future loading deflections drains should be located at mid-spans between deck supporting columns, whenever practical, and especially when deck slopes are less than 1:50 (1/4” in 12”). Positive slope to drain is attained when no standing water remains on the deck within a reasonable amount of time after rainfall stops during days with conditions that permit evaporation. Refer to Essential Elements: Roof Decks for additional information on decks and the definition of slope to drain.
3.1 Deck Types
Wood decks are not acceptable substrates for waterproofing systems covered under the RoofStar Guarantee Program.
Cast in place, monolithic structural concrete slabs and precast concrete panels with concrete topping (average 50mm thick) as well as concrete toppings over steel decks make the best substrate and are the most common deck types used for plaza, promenade and terrace waterproofing substrates. Light weight insulating concrete and shotcrete formed concrete decks are not good substrates for waterproofing and therefore are not acceptable decks for waterproofing systems covered under the RoofStar Guarantee Program.
The RoofStar Guarantee Program strongly recommends a minimum of 2% (1/4" to ft.) slope to drain for all substrates that receive waterproofing but positive slope to drain is an absolute requirement. It is recommended that drains be located at mid-spans between deck supporting columns whenever deck slopes are less than 1:50 (1/4" in 12") in order to take advantage of expected loading deflections. Positive slope to drain is attained when no standing water remains on the deck 48 hours after a rainfall stops during days with temperatures that permit evaporation. Standard weight concrete (150 pcf) can experience deflection resulting from long-term creep due to loading and to assure permanent retention of a minimum of 1% (1/8" to ft.) an initial slope of at least 2% is strongly recommended for concrete decks.
Creep in structural concrete, both reinforced and pre-stressed, due to increasing constant prolonged loading can result in deck deflections equal to three times instantaneous elastic deflection. Therefore, plaza decks with heavy overburdens (loading) require special attention from the structural engineer during the design process to ensure that load carrying capacity of the deck is adequate. The structural design of plazas must also contend with possible intermittent live loads that may exceed 50% of the total design load. The service weight of emergency vehicles such as fire trucks can concentrate excessive live loads on plaza decks that are often designed to provide access for emergency vehicles.
Concrete waterproofing decks include decks that are cast-in-place or pre-cast, and structural or non-structural in nature. The finished surface of the deck should be smooth, level, and free of moisture or frost. With cast-in-place decks, special care must be taken to ensure that the deck is cured for 28 days and that the surface is dry. For compliance with National Building Code of Canada provisions for the design and construction of buildings their structural members made of plain, reinforced and pre-stressed concrete shall conform to CSA A23.3 "Design of Concrete Structures".
- Concrete decks, walls, curbs and equipment pad surfaces must be clean (free from dirt, loose particles, paint, silicone, oil, grease, curing compounds or agents, adhesion inhibiting curing compounds and release agents as well as other contaminants). Concrete decks also must be dry and smooth (free from sharp projections) prior to commencement of waterproofing installations.
- Pitted or honey-combed surfaces must be repaired before the membrane application and is the responsibility of others, not the waterproofing contractor, unless specified otherwise. Holes or voids in the concrete substrates must be re-pointed with a non-shrinking concrete patching compound.
- Concrete decks, walls, curbs and equipment pads are not to receive adhered waterproofing for a minimum of 28 days after pouring unless expressly instructed in writing by the Project Structural Engineer. Decks formed with shot-crete and lightweight insulating concrete are not acceptable substrates for waterproofing under the RoofStar Guarantee Program.
- The moisture content levels of concrete surfaces, decks, walls, curbs and equipment pad surfaces, must strictly comply with the membrane manufacturer’s published moisture level application limitations.
- All concrete surfaces to receive adhered waterproofing shall be structurally sound, water cured, have a light hair broom finish or be prepared by mechanical means and shall be primed, when applicable, with a membrane manufacturer’s approved primer. Proper water curing techniques are strongly recommended and include continual or frequent applications of water by ponding or immersion, spraying or fogging. Concrete decks cured with compounds or sealants may not have acceptable surfaces to receive adhered waterproofing membranes. When concrete curing compounds are used on waterproofing decks removal of the compounds by mechanical means, may be necessary prior to installation of membranes, and such removal is the responsibly of others not the waterproofing contractor.
- Curbs, blocking, and nailing strips should be installed where required prior to the waterproofing contractor's acceptance of the deck.
- Pre-cast panels, post-stressed beams, or “T” and cavity decks shall have a minimum 50mm (2”) concrete topping applied over the deck prior to the application of the waterproofing membranes. Where a difference exists in the levels of adjacent surfaces, the general contractor or others shall install approved non-shrink grout or ground to match level of adjacent surfaces. Grouting or grinding shall be feathered on the lower surface a minimum distance of twelve times the amount of the vertical differential.
- Cold joints between concrete pours, at transitions between horizontal decks and vertical walls below grade, shall be sealed and covered with waterproofing membrane flashing. Membrane flashing shall cover all deck wall transitions by a minimum of 200mm (8”) and both deck and wall waterproofing or damp proofing materials must be compatible with one another. Or alternatively, whenever materials at deck and below grade wall transitions are not compatible with one another sealants and mechanically attached termination bars are acceptable, to create a watertight lap a minimum 200mm (8") in width.
126.96.36.199 Substrate Moisture Emissions
Concrete decks can retain water for extended periods and when exposed to rain the drying time will be extended beyond 28 days. Adhered waterproofing systems require concrete deck moisture levels that are low enough to ensure an adequate bond between the deck and the waterproofing materials. Many waterproofing materials application specifications require that moisture levels emitted from concrete decks not exceed three (3) pounds per thousand square feet.
Testing moisture levels that are emitted from concrete decks prior to material applications is a RoofStar Guarantee Standard and an essential step in minimizing the impact that the presence of water may have on successful waterproofing application. Moisture meters are used to determine the moisture content of concrete decks and must be performed daily by the applicator prior to waterproofing membrane installations. Capacitance testing meters measure the relative moisture content of the surface of concrete decks in order to determine the suitability of the surface (to 25mm -1" in depth) for the application of adhered materials.
Steel roof decks are most often constructed of light gauge (usually 22, 20, or 18 gauge) cold-rolled steel sections (panels) that are galvanized. In cross-section the panels are ribbed, with the ribs usually spaced at 150 mm (6") on centre. The ribs provide the strength and rigidity of the panels. Steel decks are generally supported by open-web steel joist framing and are welded or mechanically fastened to the framework. Steel decks panels must be properly aligned, squarely intersect walls, and provide a smooth level surface for waterproofing.
For compliance with National Building Code of Canada provisions for the design and construction of buildings their structural members made of cold-formed steel shall conform to Can / CSA -S136-01 (including supplement CAN/CSA -S136S1-04).
Poured concrete, gypsum or cement fibre board deck overlays are required over steel decks as acceptable substrates for all adhered waterproofing membrane systems.
- 1. Steel Decks with Concrete Overlays
- Steel decks that receive poured concrete overlays shall have vented pans to prevent entrapment of moisture. For preparation of concrete surfaces for membrane applications refer to 2.2.4 above.
- 2. Gypsum Boards on Steel Decks
- Two layers of gypsum board shall be installed over steel decks as an acceptable substrate for adhered waterproofing membranes when cast in place concrete topping is not present. The first layer of gypsum or cement board shall be either be fully mechanically fastened to the deck or adhered to the deck with manufacturer's approved compatible polyurethane adhesive. The second board layer must be adhered with a compatible manufacturer's approved polyurethane adhesive.
- All edges of the gypsum & cement boards must be fully or intermittently supported by the deck. Staggered (offset) end and side joints 300 mm (12") from adjacent board rows. All board joints that will receive liquid applied membrane systems must be taped with waterproofing manufacturer's approved joint tape.
- Each layer shall be a minimum thickness of 12.7 mm (1/2") and must be manufactured with fibreglass facers and silicone treated gypsum cores, conforming to ULC S-102 & ULC S-107. Gypsum board edges shall to be fully or intermittently supported by the deck and have joints staggered (offset) 300 mm (12") from adjacent boards, rows or layers.
- All board joints that will receive liquid applied membrane systems must be taped with waterproofing manufacturer's approved joint tape. In all other circumstances, and when required by membrane manufacturer's application specifications, tape all board joints that will receive membrane using the waterproofing manufacturer's approved joint tape.
- For board surface preparations (e.g. primer) follow membrane manufacturer's application specifications.
- 3. Cement Fibre Boards on Steel Decks
- Two layers of fibre-mat reinforced cement board shall be installed over steel decks as an acceptable substrate for waterproofing membrane applications and each layer must be a minimum thickness of 9.5 mm (3/8") as well as conform to ASTM C1325-04 Non-Asbestos Fibre-Mat Reinforced Cement Substrate Sheets.. Cement fibre-mat board edges shall to be fully or intermittently supported by the deck and have joints staggered (offset) 300 mm (12") from adjacent boards, rows as well as layers. When required by membrane manufacturer’s application specifications tape all board joints that will receive membrane with waterproofing manufacturer’s approved joint tape. For board surface preparations (e.g. primer) follow membrane manufacturer’s application specifications.
188.8.131.52 Mechanical Fastening: Gypsum Board & Cement Board Attachment on Steel Decks
When gypsum or cement boards are mechanically fastened on steel decks, as substrate overlay boards for waterproofing membranes, the first layer of gypsum or cement board shall be either fully mechanically fastened to the deck or be adhered with membrane manufacturer’s approved polyurethane adhesive. The second layer must be adhered with membrane manufacturer’s approved polyurethane adhesive. Mechanical fixation through both deck overlay board layers is not permitted.
Maximum steel deck flute width and minimum fastener requirements for gypsum and cement board used for deck overlay applications are as follows:
|Thickness||Deck Flute Width||Board Size||Screws & Metal Stress Plates||Bulgle-head Drywall Screws|
|9.5 mm (3/8”)||up to 125 mm (5")||1200 mm x 2400 mm (4' x 8’)||12||32|
|12.7 mm (½")||up to 125 mm (5")||1200 mm x 2400 mm (4' x 8’)||12||32|
|15.9 mm (5/8")||up to 200mm (8")||1200 mm x 2400 mm (4’ x 8’)||12||32|
3.2 Expansion Joints
Expansion joints are used on waterproofing decks to intentionally provide periodic breaks or gaps to accommodate movement for the expansion and contraction of the buildings as well as thier components. Typically movement is limited to a maximum of 25mm (1"). Expansion joints can be found at changes in deck direction, re-entrant building corners, and changes in deck type as well as on large decks exceeding 61meters (200') additions and buildings with extreme movement (freezers) or when isolation from vibrations is required.
3.2.2 Elastomeric Expansion Joints
Proprietary elastomeric expansion joint systems may be used at the water plane provided the expansion joint system is manufactured with an EPDM-based core and flanges that can be fully bonded to the primary membrane. Such joints must be
- a. accepted for use in the RoofStar Guarantee Program;
- b. compatible with the roof membrane and acceptable to the membrane manufacturer;
- c. designed and manufactured to accommodate building movements of at least 500% elongation at -40° C (-40° F) across its length and at all vulcanized points;
- d. factory-fabricated by means of vulcanization;
- e. manufactured as one piece, complete with all joints, details and connections;
- f. Bonded with the primary membrane in a manner acceptable to the manufacturers of both the expansion joint and the membrane to which it will be bonded.
Field splicing of proprietary elastomeric expansion joints is permitted only when made with a machine acceptable to the expansion joint manufacturer. All other field splices are not permitted.
3.2.3 Other Expansion Joints
Roof expansion joint systems that do not meet the requirements set out in 3.2.2 (above) are acceptable under the RoofStar Guarantee Program when the joints are located a minimum of 100mm (4") above the finished roof surface and are completely sheathed (covered) with membrane flashing and sloped metal flashing (for cross-reference, see D1.7.16 Roof-Wall Transitions (Expansion Joint)).
3.3 Tying Into Existing Waterproofing
Where a new waterproofing system is tied-in to an existing system, the waterproofing materials must be compatible with one another, provide a positive water cut-off to the deck and shall have an RoofStar-accepted membrane moisture monitoring sensor grid system installed between the new and existing waterproofing systems.
RoofStar-accepted membrane moisture monitoring systems are listed in the Accepted Materials section of this Manual.
Waterproofing materials and systems that are accepted for use in the RoofStar Guarantee Program include SBS Modified Bituminous, Polyvinyl Chloride (PVC) and Butyl (Isobutylene & Isoprene) pre-manufactured membranes, together with Hot Fluid-Applied, Reinforced Rubberized Asphalt Systems. Waterproofing materials and systems covered by the RoofStar Guarantee Program are listed under Accepted Materials section of this Manual. In order to qualify for full coverage under the RoofStar Guarantee Program the waterproofing system as well as installation details must comply with the RoofStar Guarantee Standards set out in this Manual, with with the Membrane Manufacturer's specifications for plaza, promenade or terrace decks applications.
5 SUBSTRATES: Walls and Planters
Gypsum board is not considered an adequate substrate to receive waterproofing on vertical surfaces.
On steel framed walls fibre-mat reinforced cement board with a minimum thickness of 9.5 mm (3/8") that conforms to ASTM C1325-04 (Non-Asbestos Fibre-Mat Reinforced Cement Substrate Sheets) is an acceptable substrate to receive waterproofing. Fibre-mat reinforced cement board is to be supplied by others unless specified otherwise, must be installed by the waterproofing contractor, and covered with membrane the same work day.
5.1.2 Concrete Wall Preparation
All concrete or masonry parapets and walls must provide a smooth, clean, dry surface for membrane adhesion. Alternatively walls that do not provide a smooth, clean, dry surface for membrane adhesion may be sheathed with a minimum 15.9 mm (5/8") treated plywood or 9.5 mm (3/8") reinforced cement board that conforms to ASTM C1325-04. Boards must be mechanically attached or adhered to the wall with polyurethane adhesive. When waterproofing is applied directly to masonry parapets or walls follow RoofStar Guarantee Standards and manufacturer's printed instructions.
5.1.3 Walls at Decks Not Supported by the Wall
A parapet wall is required at adjoining walls were the deck is not supported by the wall (expansion joint) and shall be sheathed with minimum 15.9 mm (5/8") plywood or 9.5 mm (3/8") reinforced cement board that conforms to ASTM C1325-04. Wall sheathing shall be fastened to preservative treated blocking or to steel stud framing that is attached solidly to the deck and not the wall. Compressible insulation is to be installed between the sheathing and the wall and an accepted expansion joint membrane as well as metal counter flashing shall be installed.
Non-structural planter walls that are located above protection and drainage board layers, without penetrating waterproofing membranes, are strongly recommended whenever practical. When planter walls have structural reinforcements that penetrate membranes, only the use of pre-curbs or start-up curbs that are a minimum height of 100mm (4") above the deck are acceptable for coverage under the RoofStar Guarantee Program.
For further reference, see Section 12 below, LANDSCAPING, PLANTERS & OTHER VEGETATED OVERBURDENS, together with Construction Detail drawing F1.7.6 - Walls (Planter Pre-Curb Wall).
RoofStar-accepted waterproofing membrane systems listed in the Accepted Materials section of this Manual include the following:
- Two Ply SBS Modified Bituminous Membranes
- Butyl Elastomeric Single Ply Membranes
- Poly Vinyl Chloride (PVC) Plastomeric Single Ply Membranes
- Hot Fluid - Applied, Rubberized Asphalt Systems.
Only waterproofing membrane systems that are fully adhered and have an accepted protection layer installed above the membrane (protected) qualifies for coverage under the RoofStar Guarantee Program.
All waterproofing system accessory components must be supplied or be accepted for use by the membrane manufacturer. Refer to the Waterproofing Accepted Materials section for individual manufacturer accessory components and material listings.
All materials must be protected from weather by properly stacking above ground or deck surfaces and keep in factory packaging or other adequate covering until applied.
6.2 Material Selection
See Accepted Materials for Waterproofing Systems.
6.3.1 SBS Modified Bitumen Membranes
Not all membranes are ideal or even acceptable for every type of application. Below is a table that outlines the new minimum thickness and puncture resistance requirements for SBS-modified bituminous membranes, based on what type of assembly they will be used in (effective for projects bid after March 1, 2018). The far right columns pertain to waterproofing plazas, promenades and terraces:
|Exposed Roof Systems||Protected Roof Systems||Grade-level|
|Conventionally Insulated / Uninsulated Systems||Built-in
|Type, Reinforcement, Grade||Guarantee Term||mm||mm||mm||mm||mm||mm||mm||(N)||mm||(N)|
|Minimum Combined 2-ply Thickness|
|Base (Fibreglass) - Gr. 3|
|Base (Composite fibreglass) - Gr. 3|
|Base (Polyester) - Gr. 3|
|Base (Composite) - Gr. 3|
|Factory Laminated Base (panel)|
|Film Cap (Fibreglass) - Gr. 2|
|Film Cap (Polyester) - Gr. 2|
|Film Cap (Composite) - Gr. 2|
|Granule Cap (Fibreglass) - Gr. 1|
|Granule Cap (Polyester) - Gr. 1|
|Granule Cap (Composite) - Gr. 1|
Notwithstanding the limitations and requirements outlined in the table above, the following RoofStar Guarantee Standards still apply:
.1 All SBS Modified Bituminous membrane waterproofing systems shall consist of two plies of membrane. The top ply or cap sheet shall have a minimum thickness of 3.0 mm and a minimum reinforcement weight of 180g/meter squared polyester or equal strength combination reinforcement. In addition, both base plies and cap sheets in combination shall have a minimum thickness of 6.0mm or greater.
.2 Both the base sheet and cap sheet must be installed in a parallel direction (not at 90° to each other). Manufacturer's published instructions for membrane overlaps, sheet installation configurations, corner gussets (reinforcement) and membrane flashing applications shall be strictly followed. Membrane reinforcement gussets shall be installed at all inside and outside corner transitions prior to installation of membrane flashing (stripping).
.3 Only fully adhered SBS base and cap sheets that are either torch applied or are adhered in hot fluid applied rubberized asphalt qualify for coverage under the RoofStar Waterproofing Guarantee program. NOTE: Direct torch applications to wood surfaces are not permitted.
.4 Membrane end lap corners must be cut on a bias (clipped or trimmed on an angle) prior to forming laps on all torch applied modified bituminous membranes and granules are to be embedded on cap sheets prior to forming laps or seams.
.5 To view manufacturer-specific installation guidelines for SBS-modified bitumen waterproofing membranes, see Waterproofing Special Applications.
6.3.2 Thermoset Membranes
.1 Butyl single-ply thermoset waterproofing membranes used for waterproofing systems shall be fully adhered to RoofStar-accepted substrates and shall be a minimum thickness of 1.5mm (0.060”).
.2 Only proprietary adhesives that are specifically accepted by the membrane manufacturer may be used to install Butyl membrane waterproofing systems.
.3 Perimeter fixation for membrane securement (mechanical, adhesive, or adhesive tape), installed to manufacturer’s published specifications, is required for all Butyl waterproofing membranes.
.4 Reinforced flashing (stripping) membranes shall be installed at all horizontal and vertical transitions, deck penetrations, and protrusions (pipes, curbs, drains, sleepers, etc.). Reinforcement flashing membrane must be a minimum thickness1.5mm (0.060”) and shall be fully adhered to substrates.
.5 To view manufacturer-specific installation guidelines for thermoset waterproofing membranes, see Waterproofing Special Applications.
6.3.3 Thermoplastic Membranes
.1 PVC (Polyvinyl Chloride) single ply thermoplastic waterproofing membranes shall be reinforced, must be fully adhered to acceptable substrates, and shall be a minimum thickness of 1.5mm (0.060”).
|Exposed Roof Systems||Protected Roof Systems||Grade-level|
|Conventionally Insulated / Uninsulated Systems||Built-in
|Type, Reinforcement, Grade||Guarantee Term||mm (mils)||mm (mils)||mm (mils)||mm (mils)||mm (mils)||mm (mils)||mm (mils)||mm (mils)|
|5||1.270 (50)||X||1.270 (50)||1.270 (50)||1.524 (60)||1.270 (50)||1.270 (50)||1.524 (60)|
|10||1.524 (60)||X||1.524 (60)||1.524 (60)||1.524 (60)||1.524 (60)||1.524 (60)||1.524 (60)|
|15||2.032 (80)||X||2.032 (80)||2.032 (80)||2.032 (80)||X||2.032 (80)||X|
.2 Only proprietary adhesives that are specifically accepted for use by the membrane manufacturer may be utilized to install PVC thermoplastic waterproofing membranes.
.3 Perimeter fixation for membrane securement (mechanical, adhesive, or adhesive tape), installed to manufacturer’s published specifications, is required for all PVC thermoplastic waterproofing membranes.
.4 A reinforced flashing (stripping) membrane shall be installed at all horizontal and vertical transitions as well as deck penetrations (pipes, curbs, drains, sleepers, etc.). Reinforcement flashing membranes must be fully adhered to acceptable substrates and shall be a minimum thickness of 1.5mm (0.060”).
.5 To view manufacturer-specific installation guidelines for Thermoplastic waterproofing membranes, see Waterproofing Special Applications.
6.3.4 Hot Fluid-Applied, Rubberized Asphalt Membrane
- Hot Fluid-Applied, Rubberized Asphalt membrane systems shall consist of a minimum of two coatings; the first coat shall be a minimum of 90 mils thick and the second coat a minimum of 125 mils thick. A continuous reinforcement scrim of a minimum 1.35 oz/square yard spun bonded polyester fabric shall be firmly embedded into the first coating of hot rubberized asphalt while installation EVT.
- All construction joints, minor concrete cracks and deck cover board joints shall receive a pre-treatment of 90 mil thick coating of hot rubberized asphalt and reinforcement fabric prior to the first membrane coating. Coating and fabric reinforcement shall span a minimum of 75mm (3”) beyond the extent of minor cracks and joints.
- To view manufacturer-specific installation guidelines for hot fluid-applied rubberized asphalt waterproofing membranes, see Waterproofing Special Applications.
7 PERIMETER FLASHING: Membranes
7.1.1 Bituminous Elastomeric & Plastomeric Membranes
- A reinforced flashing (stripping) membrane, elastomeric, plastomeric or modified bituminous, shall be installed at all major cracks, horizontal and vertical transitions as well as deck penetrations and protrusions ( pipes, curbs, drains, sleepers, etc.). Elastomeric and plastomeric reinforcement flashing membranes shall be a minimum thickness of 1.5mm (0.060”). Modified bituminous reinforcement flashing membranes shall be a minimum thickness of 3mm and be equal to 180g/meter squared polyester or equal strength composite reinforcement.
- A layer of asphalt core protection board or SBS modified bituminous membranes shall be installed to all vertical and horizontal surfaces and must be firmly embedded into the second coating of hot rubberized asphalt while above installation EVT. Asphalt core protection board shall be a minimum thickness 4.5 mm (3/16"). Alternatively, an SBS Modified bituminous granulated cap sheet, with a sanded bottom surface that is minimum thickness of 3.7 mm and is reinforced with minimum 180g/meters squared polyester or equal strength composite reinforcement may be used as the membrane protection layer. Composite reinforcement (fibreglass/polyester) membranes are strongly recommended when membranes are embedded in hot rubberized asphalt as their physical properties are more dimensionally stable than membranes reinforced with polyester only.
- Membrane flashing (stripping) details (with the exception of low parapets, planter wall pre-curbs, and low door sill details) must be designed to provide a minimum 200 mm (8") sealed height above the waterproofing membrane and not less than 100mm (4”) above the waterproofing system finished surface. Finished surface is defined as the top of the waterproofing assembly, be it concrete pavers, ballast, unit masonry, or growing medium (soil), etc.
- All exterior perimeter walls that have waterproofing terminating at or near the top of walls must have membrane flashing (stripping) that overlaps the exterior finish (i.e. wall cladding) by a minimum of 50 mm (2"). On high parapet walls, that are completely flashed with metal, where membrane flashing (stripping) is terminated part way up the wall (without a reglet detail) the remainder of the parapet shall be covered with a flashing underlay of a minimum 40 mils or 1 mm (.040") self-adhered modified bitumen membrane; 15 lb. felt is not acceptable.
- All membrane flashing (stripping) terminating at cladded (i.e. stucco, siding, etc.) walls must lap under the sheathing membrane and cladding by minimum of 75 mm (3"). All walls and up stands shall be covered with sheet metal base flashings.
- All membrane flashing (stripping) terminating under a reglet must be sealed to the wall with a compatible mastic and covered with metal flashing that terminates in a reglet.
- Where a wall or conventional separation / expansion joint detail intersects with a higher wall; the membrane flashing (stripping) must be sealed by reinforcement gussets (membrane saddles) that are formed to reinforce the inside and outside corners.
- New construction projects must follow proper sequencing. Where waterproofing membrane flashings (stripping) overlaps work by others (i.e. siding, stucco, cladding, , etc.) this work shall be complete prior to the installation of metal flashing or wood blocking must be installed to facilitate the future installation of the exterior wall finishes. When flashing membranes lap under work by others (siding, stucco, glazing, cladding, etc.), the membrane and metal flashings shall be installed prior to any wall coverings. Any variance to proper detail sequencing must be approved by the design authority in writing.
- Door sill flashing membranes (stripping) may be less than 200 mm (8") in height but shall not be less than 100 mm (4") above the primary waterproofing membrane and must be installed to comply with the following conditions:
- A metal water stop flashing, formed with pan folded, welded or soldered corners must be mechanically attached to inside of door sill framing or opening and be sealed with membrane flashing (stripping).
- Membrane flashing, (stripping) or metal pan sill flashing must be installed at doorjamb framing or opening to a minimum height of 100 mm (4") above door sill framing or opening, prior to installation of doorjambs and door sills. Membrane gussets must be installed at sill corners.
- Metal pan sill flashing or RoofStar-accepted reinforced liquid flashing systems must be installed wherever clearances preclude the use of membrane flashing (stripping) to seal door sill details.
- Slopes must be provided to direct water away from door sill details. (Overhangs and overflow drains are recommended wherever practical).
8 MEMBRANE PROTECTION
A RoofStar-accepted membrane protection layer (asphalt core board, cap sheet or protection mat), must be installed by the waterproofing contractor, and be compatible with waterproofing membrane. The protection layer shall be installed and secured, as soon as possible, upon completion of waterproofing membrane installation. Construction traffic, by other than waterproofing trade and membrane moisture monitor technicians, is not permitted until the membrane protection layer is completely installed and secured.
9.1 Material Selection
Extruded expanded polystyrene (Type 4), conforming to CAN/ULC-S701 (latest edition) with a compressive strength of 240 kPa (35psi) is the only commercially produced insulation suitable for use over waterproofing and protected membrane roofing systems. Extruded expanded polystyrene is available in a 600mm x 1200mm (2'x4') board size, has an aged R value of 5.0 per inch (RSI 0.87) and ranges in thickness' from 25mm (1") to 100mm (4").
Insulation joints shall be offset or staggered a minimum of 300 mm (12") from adjacent layers and rows.
An accepted drainage layer & filter mat shall be installed on the top surface of extruded polystyrene insulation whenever pavers, gravel ballast, unit masonry or growing mediums (soil) are used as overburdens or wearing courses over waterproofing.
Pavers on pedestals promote free subsurface drainage at the membrane level and are therefore strongly recommended whenever practical. When pedestals are not used as the drainage layer a proprietary geosynthetic drainage core panel is required over waterproofing membranes and is placed above protection boards or extruded polystyrene insulation. Geocomposites and Geosynthetic drainage panels are designed with openings to direct excess subsurface water to deck drains. Geosynthetic drainage cores are typically molded (dimpled) or woven plastic grids, that is a minimum of 9.5 mm (3/8") thick or thicker and is designed to provide uniform support as well as traffic-bearing properties for overburdens and wearing courses. Proprietary geocomposites and geosynthetic panels must be designed with sufficient compressive strength to support the design load of overburdens as well expected live loads and be acceptable for use by the membrane manufacturer.
Filter fabrics (mats) must be installed to a sufficient height at all up-stands, be properly lapped at joints and side laps as well as tightly fitted around all penetrations and protrusions, in order to eliminate the intrusion of overburden or wearing course materials. In order to prevent moisture from being driven into extruded polystyrene insulation drainage board surfaces must not be in direct contact with more than 40% of the insulation board surfaces.
10.2 Material Selection
Only geosynthetic drainage cores and geocomposites with factory laminated filter fabric, which are designed to resist damage from the weight of the specified overburden, are acceptable for use in the RoofStar Guarantee Program. Refer to the overburden specifications of the project, and membrane manufacturer requirements, when selecting the appropriate material.
- Only manufacturer's proprietary purpose made pedestals, with integral spacer ribs for uniform spacing between pavers, that provided a minimum ventilating air space height of 12.5 mm (1/2") are acceptable for use with concrete pavers and other unit masonry products. For waterproofing systems with extruded polystyrene insulation the drainage layer shall be placed on the top surface of the insulation.
- When manufacturer's proprietary pedestals are not used for drainage a continuous purpose made manufactured geosynthetic drainage core or geocomposites shall be installed under all overburdens or wearing courses. Geosynthetic drainage cores and geocomposites shall be molded (dimpled) or woven plastic grids, shall be a minimum of 9.5 mm (3/8") thick or greater, and shall provide uniform support as well as traffic-bearing properties for overburdens and wearing courses. Only geosynthetic drainage cores and geocomposites with factory laminated filter fabric, which are designed to resist damage from the weight of the specified overburden, are acceptable for use in the RoofStar Guarantee Program. Refer to the overburden specifications of the project, and membrane manufacturer requirements, when selecting the appropriate material.
- Filter fabric (mat) is required for all overburdens that include intrusive materials, growing medium, sand, gravel, mortar, etc. and may be either factory laminated to geocomposites or field installed over geosynthetic drainage cores. Filter fabric shall be installed to a sufficient height at all up-stands, lapped at joints and must be fitted around all penetrations as well as protrusions in order to eliminate the intrusion of overburden and or wearing course materials.
- In order to prevent moisture from being driven into extruded polystyrene insulation (water vapour transmission) geosynthetic drainage board and drainage composites surfaces must not be in direct contact with more than 40% of the insulation board surfaces.
11 WEARING COURSE and OVERBURDEN
In this Manual, a “wearing course” or “overburden” is used to denote any manner of material, equipment or installation that is situated on top of, and covering all or a portion of, a waterproofing membrane assembly.
Wearing courses or overburdens for plaza deck waterproofing systems are classified either as accessible or inaccessible. Waterproofing Systems for pedestrian and emergency vehicle traffic on plaza decks are often designed with inaccessible wearing courses or overburdens. In contrast, Protected Membrane Roofing Systems on plaza/terrace decks are almost always designed with accessible wearing courses for pedestrian traffic and utilize pavers on pedestals.
Accessible wearing courses and overburdens are reasonably easy to remove for access to the membrane. Inaccessible wearing courses or overburdens require demolition or substantial material removal to gain access to the membrane, and are often constructed with cast-in-place concrete protection slabs (split-slab) or brick, tile or stone set in mortar beds.
Inaccessible Overburdens may also include soils (and associated plants), vegetative assemblies in a growing medium greater in depth than 150 mm (6”), and water features or equipment installations (non-structural but not easily moved). As a result of the potentially high cost of demolition to access membranes under Inaccessible wearing courses or overburdens, the performance criteria for these waterproofing systems are higher. To qualify for coverage under the RoofStar Guarantee Program, an electric membrane leak detection system is required in order to identify and locate membrane breaches that may occur during the waterproofing system’s service life.
The RoofStar Guarantee Program strongly recommends the use of wearing surfaces that permit relatively easy access to the membrane. Waterproofing systems that incorporate in the design either Accessible Wearing Courses of a more complex nature, or Inaccessible Wearing Courses, such as poured-in-place concrete, asphalt paving and wearing surfaces units set in mortar beds, etc. must meet additional standard requirements for coverage under the RoofStar Guarantee Program.
11.2.1 Accessible Wearing Courses
An Accessible Wearing Course is limited to a maximum of 150 mm (6”) in depth. Accessible Wearing Courses can be comprised of various materials, subject to some limitations.
Concrete pavers on pedestals permit easy access to waterproofing membranes and therefore are the best choice (whenever practicable) for an Accessible Wearing Course over all waterproofing systems. When pavers are used as the walkway material, they must be spaced no closer than 3mm (1/8″) and must be supported by non-abrasive pads or proprietary pedestals providing a minimum of 12.5 mm (1/2″) of vertical separation layer for airflow and levelling. The choice of pedestal or drainage layer type is the responsibility of the design authority. Pedestals provide airflow for drying surfaces and assist in leveling. They should not impede the flow of water or air, and should uniformly distribute the dead load of pavers and predicted live loads.
An Accessible Wearing Course may include installed unit masonry, brick, tile or stone (placed on sand and or gravel beds), and both Extensive and Intensive Vegetative Assemblies. That said, some of these types of wearing courses are more difficult to remove than pavers on pedestals. Consequently, an installed electric leak detection system may be mandatory. For further information and the RoofStar Guarantee Standards applicable to leak detection systems, see 13.3.2 below.
In the event the waterproof membrane requires repairs or maintenance, Accessible Wearing Courses will be removed and reinstalled under the terms and conditions of the RoofStar Guarantee. Replacement of any components that cannot be reinstalled, due to breakage or other factors, remains the responsibility of the Owner.
11.2.2 Inaccessible Wearing Courses
Wearing Courses greater than 150 mm (6”) in depth, regardless of their composition, are considered Inaccessible. Typically, an Inaccessible Wearing Course is one designed for pedestrian and emergency vehicle traffic on plaza decks, and includes cast-in place concrete protection slabs (split-slab) and brick, tile or stone set in mortar beds. Because Inaccessible Wearing Course designs require demolition for access to the membrane, an installed electric leak detection system is mandatory. Electric leak detection systems that are specifically accepted by the RoofStar Guarantee Program are listed in the [Accepted Materials: Leak Detection & Monitoring Systems] section of this Manual.
Solid cast-in place concrete protection slab (split-slab) and asphalt paving wearing courses shall incorporate surface score lines (indents) to facilitate cutting for removal of wearing course sections in order to locate possible breaches in membranes. Score lines shall be straight edged grid patterns (squares, rectangles, diamonds, etc.) with indents spaced at a maximum of two (2) metres apart.
Because of their nature, the removal and reinstallation or replacement of Inaccessible Wearing Courses is not covered under the terms and conditions of a RoofStar Guarantee.
12 MEMBRANE MOISTURE SURVEYS & MONITORING SENSOR GRIDS
A membrane moisture survey (see 13.3.1) is required for all waterproofing membrane systems, prior to the installation of any overburden or wearing course.
When mandated in this Manual, an electronic leak detection system (13.3.2) shall be installed on the waterproofing membrane, or placed over protection boards or SBS membranes that have been set in hot fluid-applied modified asphalt, prior to the application of overburdens or wearing courses. The leak detection system may be constantly monitored, but ongoing monitoring is not a requirement of the RoofStar Guarantee Program.
12.2 Flood Testing
Flood Testing is not a recommended practice but is at the discretion of the design authority or owner. If flood testing is required to water test waterproofing membranes, testing shall be conducted prior to installation of insulation and overburdens and be performed to ASTM D5957 - 98.
12.3.1 Moisture Scan Survey
Membrane moisture survey scans must be performed on all waterproofing membrane systems by an independent Moisture Detection Company that is specifically recognized by the RoofStar Guarantee Program.
12.3.2 Leak Detection Systems
Only electronic leak detection systems (utilizing high or low voltage) recognized for use in the RoofStar Guarantee Program may be installed and monitored on waterproofing systems designed and accepted by the RoofStar Guarantee Program. The following types of wearing courses do not require installation of an electric leak detection system:
- pavers on pedestals
- gravel ballast with a maximum depth of 100mm (4")
- an Extensive Vegetative Waterproofing Assembly, or
- an Intensive Vegetative Waterproofing Assembly with a soil depth of less than 150 mm (6”)
An installed electronic leak detection system is mandatory on waterproofing systems covered by Accessible Wearing Course that includes
- unit masonry, brick, tile or stone (placed on sand and or gravel beds), or
- an Intensive Vegetative Waterproofing Assembly with a soil depth equal to or more than 150 mm (6”),
- water features or equipment installations (non-structural but not easily moved).
An installed electronic leak detection system is also mandatory on all waterproofing systems covered with Inaccessible Wearing Courses. Regardless of the recognized leak detection technology employed, the leak detection system must provide detection capabilities for the entire deck surface and extend leak detection a minimum of 50 mm (2") vertically from the water plane at
- all transitions;
- any point along the entire deck perimeter; and at
Where the electronic leak detection system of choice utilizes a sensor ribbon installed on the waterproofing membrane in a grid pattern, the ribbon spacing shall be no more than three (3) metres in any direction for waterproofing systems covered by an Accessible Wearing Course, and no more than two (2) metres in any direction for waterproofing systems covered by an Inaccessible Wearing Course.
13 LANDSCAPING, PLANTERS & OTHER VEGETATED OVERBURDENS
SBS Modified Bituminous membranes used on Landscaped and Vegetated roofing systems shall consist of two plies and the top ply (cap) must be a minimum thickness of 3.7 mm on the selvedge edge, with a minimum 180g / meters squared polyester or equal strength combination reinforcement. Thermoset and Thermo Plastic (EPDM, TPO, PVC) single ply membranes used for Landscaped and Vegetated roofing systems shall be fully adhered and a minimum thickness of 1.5mm (0.060").
13.2 Membrane Protection
Protection for roofing membranes is required during the installation and maintenance of landscaping, extensive and intensive vegetated (green) roofing installations. The minimum membrane protection must be installed by the roofing or waterproofing contractor and shall be 3 mm (1/8") asphalt core protection board or 25 mm (1") minimum extruded polystyrene insulation plus filter mat, root intrusion barrier, and drainage layer. Tightly butt all protection and insulation boards, overlap all filter mat seams and seal all laps of roof intrusion barriers to RoofStar Guarantee Standards and manufacturer’s installation instructions.
The Membrane Manufacturer and the RoofStar Guarantee Program must confirm acceptance of other alternative protection systems or components in writing. Damage to membranes and flashings that results from the use of plants with aggressive root structures, (Bamboo, Willow etc.) for landscaped and green (vegetated) Waterproofing systems, is not the responsibility of the RoofStar Guarantee Program and is specifically not covered under the RoofStar Guarantee. For additional information refer to the latest addition of the British Columbia Landscape Standard, Green Roof Section.
13.2.1 Root Barriers & Separation Zones
Proprietary root intrusion barriers must be acceptable to the Waterproofing membrane manufacturer and appropriate for the vegetation system installed. Polyethylene or polypropylene sheeting used as a root barrier shall be a minimum thickness of .2 mm (8 mils). Root Barriers shall be sheets or boards installed in a continuous plane above the roof membrane, carried up the inside of soil retention perimeters (separation zones), and must be installed with sealed laps and seams as per manufacturer's instructions.
Separation Zones that are free of growing medium and vegetation are required around all waterproofed perimeters, up-stands, drains, penetrations, mechanical equipment, expansion joints, etc. Zones must be a minimum of 300 mm (12”) wide and constructed with curbs or other physical barriers that separate and facilitate drainage. Physical barriers must be placed above the membrane protection layers and must not be attached through or penetrate the roof membrane.
A drainage layer is required. Specialized proprietary drainage products must be acceptable to the membrane manufacturer.
13.3 Planter Design & Waterproofing
13.4 CSA A123.24 and Wind Uplift
All vegetative overburdens using a modular system are required to meet CSA A123.24 “Standard test method for wind resistance of modular vegetated roof assembly” (latest edition).
13.5 Flood Testing
13.6.1 Extensive Vegetative Overburdens
Where Extensive Vegetative Overburdens are installed as part of the waterproofing specification and / or contract (Extensive Vegetative Waterproofing Assemblies are defined as roof top gardens having minimal plant species diversity, irrigated only to establish plants, and typically having a soil depth of less than 150 mm or 6 inches) the costs for removal and replacement of soil to access the membrane, to investigate or repair leaks in the membrane, are included in the RoofStar Guarantee coverage. However, the removal and replacement of plants, irrigation lines and or equipment, electrical lines, landscape and decorative features such as concrete pads, statues, planters, large rocks, etc., to investigate or repair leaks in the membrane, is not included, and is the responsibility of others. Subsequently, such access shall be provided and/or paid for by others.
13.6.2 Intensive Vegetative Overburdens
Where Intensive Vegetative Overburdens are installed as part of the waterproofing specification and/or contract (Intensive Vegetative Waterproofing Assemblies are defined as roof top gardens with diverse plant species, irrigated for maintenance and typically having a soil depth equal to or more than 150 mm or 6 inches), and where the soil thickness of Intensive Vegetative Roof Assemblies exceeds 200 mm (8″), the removal and replacement of soil and plants to access the membrane to investigate or repair leaks in the membrane is the responsibility of others, and such access shall be paid by others. In addition, the removal and replacement of plants, irrigation lines or equipment, electrical lines, landscape and decorative features such as concrete pads, statues, planters, large rocks, etc., to investigate or repair leaks in the membrane is also the responsibility of others, and such access shall be provided and or paid for by others.
Structural planters that incorporate pre-curb or start-up curbs for walls that are completely sealed with membrane and are a minimum of 100 mm (4") in height, as illustrated in Construction Details, qualify for RoofStar Guarantee coverage. Waterproofing liners in planters with structural walls, concrete curb or other materials, that do not incorporate pre-curbs shall be isolated and separated from the guaranteed roofing membrane and are specifically not accepted under the RoofStar Guarantee.
Non-structural planters placed over landscaped deck and roofing membranes, with an appropriate protection layer, are strongly recommended whenever practical. Structural planters that incorporate pre-curb or start-up curbs for walls that are completely sealed with membrane and are a minimum of 100 mm (4") in height qualify for RoofStar Guarantee coverage (Refer to Construction Details for both Low Slope Roofs and for Waterproofing.
A design authority or membrane manufacturer may specify a proprietary walkway protection system or warning zone membrane over the primary roof membrane. Walkway and warning zone materials are not part of the roofing membrane assembly but are typically accessory products that are placed over completed roof membranes. Subsequently the type and performance of any walkway or warning zone material is specifically excluded from coverage under the RoofStar Guarantee, as is any detrimental effect the materials may have on the roof system.
14 PENETRATIONS and DRAINS
Deck penetrations, pipes, curbs, drains, etc. shall NOT be installed less than 200 mm (8") from one another or the base of walls and other construction details unless specifically authorized by the inspection agency as a special condition. These items are to be located by others.
14.2 Strip-in Curbs
Curb mountings for all venting units, equipment, pipes and cables on waterproofing decks are strongly recommended. Curbs are to be supplied and installed by others. Curbs are to be a minimum 200 mm (8") sealed height above the waterproofing membrane and not less than 100mm (4”) above the waterproofing system finished surface (overburden). Only purpose made non-ferrous metal strip-in type vents will be permitted for use with waterproofing systems.
14.3 Pipe & Cable Flashing
Pipes, cables and multiple roof penetrations, including grouped pipes and or cables, must incorporate purpose-made weather head seals. Purpose-made multiple penetration weather head seals must provide a positive weather seal by use of metal hoods, manufacturer's proprietary rubber based friction seals, mechanical clamps or gooseneck type designs. Gum boxes or pitch pans are not permitted for use with waterproofing systems.
14.4 Drains and Scuppers
- The use of bi-level drains with adequate openings for both surface and subsurface drainage are mandatory for all inaccessible waterproofing systems that utilize interior drainage systems with low permeable wearing courses (poured concrete, bricks, unit masonry and stone set in mortar beds).
- Membrane flashing reinforcement is required for drains and other roof accessories and is to be installed as per waterproofing membrane manufacturer's published application instructions.
- When cast-iron drains are used; a sump receiver and under-deck clamp must be provided and installed by the trade supplying the deck drain.
- All flange type drains as well as flow through wall drains and scuppers shall be constructed of non-ferrous materials.
- On all waterproofing projects all drains connected to internal piping shall be connected by mechanical compression type seals only. "O"-rings, mastics and caulking are not acceptable methods to seal drains to internal piping.
15 PERIMETER FLASHING: Metal
All protrusion and penetration flashings, vents, curbs, sleepers, pipes cable, drains, etc. shall NOT be installed LESS than 200mm (8") from the base of walls, cants or installed equipment, protrusion or other penetration flashings.
Metal base flashing shall be kept approximately 25 mm (1") above gravel to prevent immersion in water with the exception of protected and modified protected waterproofing systems.
Gravel-stop type flashings may be used, provided manufacturer's printed instructions are followed The exceptions are overflow drains and roof scuppers that are installed through walls. These items are to be located by others.
Sheet metal flashings are designed to divert water away from the membrane flashing termination, usually onto the roof. The metal flashing also protects the membrane from deterioration due to the elements and from mechanical damage. The metal flashing is not a waterproofing membrane, therefore the roofing membrane should be continuous under the metal (see Metal Flashing Details).
For further details, the Sheet Metal and Air Conditioning Contractors National Association, Inc. (SMACNA) publishes a reliable reference for the proper design and installation of architectural sheet metal. The Architectural Sheet Metal Manual is available from:
- Sheet Metal and Air Conditioning Contractors National Association, Inc.
- c/o British Columbia Sheet Metal Association
- 156 - 4664 Lougheed Hwy Burnaby, B.C. V5C 5T5 (604) 299-4641
15.2 Material Selection
The following minimum gauges and / or weights of commonly used metals or alloys will be applied to all projects under the Guarantee Program. The length of metal flashing shall be limited to a maximum of 3.04 m (10').
GALVANIZED STEEL: 0.50 mm (0.0196", 26 gauge) galvanized steel sheet, conforming to ASTM A653 / A653M-06 CS Type B, Z275 (G90) coating. Thickness tolerance as per ASTM A924/A924M-06 ±0.08 mm (0.003") for sheet widths not exceeding 1500 mm (60").
ALUMINIUM – ZINC ALLOY COATED STEEL: 0.50 mm (0.0196", 26 gauge) aluminium-zinc alloy coated steel sheet, conforming to ASTM A792/A792M-06 CS Type B, AZM150 (AZ50) coating. Thickness tolerance as per ASTM A924/A924M-06 ±0.08 mm (0.003") for sheet widths not exceeding 1500 mm (60").
ALUMINIUM: 0.80 mm (0.032", 20 gauge) aluminium sheet, utility quality to CSA HA Series - 1975, plain or embossed finish. Maximum thickness tolerance variation ± 0.06 mm (0.0025") based on 1200 mm (48") wide sheet.
STAINLESS STEEL: 0.38 mm (0.014", 28 gauge) stainless steel, Type 302, 304, 316, 2B finish to ASTM A167-82. Maximum thickness tolerance variation ± 0.04 mm (0.0015") based on 1200 mm (48") wide sheet. COPPER: 0.56 mm (0.022", 16 oz.) copper sheet, cold rolled roofing copper to ASTM B370-81. Maximum thickness tolerance variation ± 0.09 mm (0.0035") based on 1200 mm (48") wide sheet.
ZINC: 0.80 mm (0.031") zinc Sheet conforming to European standard EN 988-1996. Maximum thickness tolerance variation ± 0.03 mm (0.0012").
The use of concealed in-seam fasteners is required. Any fastening of metal flashings on the top of parapet surfaces is strongly discouraged and is not permitted as the only attachment method.
If top-surface fastening must be used because of a specific job site condition, only appropriate screw-type fasteners with neoprene washers may be used. Nails are not acceptable. The outside and inside face of metal cap flashing must be attached with cladding fasteners (screws), and/or concealed clips. Continuous and discontinuous concealed clips and or cladding screw fasteners or a combination of these attachment methods are acceptable to secure metal cap flashing. No fastening of flashing is permitted within 87.7 mm (3-1/2") of the roof surface. Note: Cladding fasteners or concealed clips are not required on the inside face of roof edge cant strip details.
Cladding fasteners (screws) with gasketed washers, used as exposed fasteners for metal flashing, must be No. 8 or better, made of metal compatible with and corresponding in colour to, the flashing material being installed. Nails are not acceptable as exposed fasteners. The minimum number of cladding screws used to face fasten metal cap flashing shall be three (3) fasteners equally spaced (±10%) between seams of flashing formed from 3000 mm (10 ft.) metal stock and a minimum of two fasteners equally spaced (±10%) between flashing seams formed from 2400 mm (8 ft.) metal stock. Concealed clips, both continuous and discontinuous, shall be formed from the same metal type as the flashing being secured and be minimum 24 gauge in thickness. In addition, concealed clips are to be fastened as close to the bottom edge (hook) as practical but must not be fastened further than a maximum of 75 mm (3") from the bottom edge (hook). Concealed clips must engage drip or safety edges by a minimum of 12.7 mm (1/2").
Continuous Concealed Clips are to be attached with appropriate corrosive resistant fasteners spaced at a maximum of 300 mm (12") o/c. Discontinuous Concealed Clips shall consist of a single clip centred between the seams of each length of metal flashing. Clips shall be a minimum of 1000 mm (40") in length for flashing formed from 3000 mm (10 ft.) metal stock and a minimum 800 mm (32") in length for 2400 mm (8 ft.) metal stock. Discontinuous clips for shorter flashing lengths shall be approximately 1/3 the length of the metal flashing but not less than 100 mm (4") in length. Corrosive resistant fasteners for clips, to be spaced a maximum of 300 mm (12") o/c.
15.4 Curb Heights
On all waterproofing assemblies the minimum curb height (equipment curbs, vent curbs, etc.) shall be 200 mm (8") above the roof surfacing. Surfacing is defined as the top of the waterproofing assembly, regardless of the type of wearing course.
Standing seams and S-lock seams are both acceptable.
Seaming of inside corners shall be carried to the base of the cant or the base of the metal. S-locks shall be fastened before the insertion of successive flashings. .2 Lap seams are acceptable only where the vertical run on the inside corner is less than 100 mm (4").
When the vertical height exceeds 300 mm (12"), standard seaming practices will be followed. When cants are not used on curbs, standard seaming practices (standing seams) shall be followed at all times, with the exception of the vertical flashing portion that is lapped to fit under counter flashing or equipment flanges.
For roof curb-flashing seams ( e.g. equipment, skylights, etc.), which do not exceed 300 mm (12") in height, lap-type seams may be used on the vertical portion provided standing seams are used in the cant area.
The design authority shall choose and specify the seaming system.
15.6 Cap Flashings, Base Flashings and Reglets
The top surface of walls (parapets, expansion joints, firewalls, roof dividers, etc.) wider than 100 mm (4" nominal) shall be constructed to provide positive slope to drain and be covered with metal cap flashing. Provide a reglet for all flashings terminating in concrete or masonry walls. When wall flashing terminates in a reglet, typically on high parapet walls, a coping flashing is required at the top of the parapet wall (see Metal Flashing Details). On new construction projects reglet and sloped wood blocking at top surface of concrete or masonry walls are to be installed by others.
Metal base flashings are required on all walls and curbs on roof systems that utilize gravel ballast filter mats, and must “kick out” minimum 50 mm (2") over insulation and filter fabric.
Reglet must be 200 mm (8") minimum to 300 mm (12") maximum above the waterproofing surface. Waterproofing surface is defined as the top of the waterproofing assembly, be it membrane or ballast.
In the case of multi-wythe masonry, composite walls, or parapets, and where not restricted by seismic codes, continuous flexible thru-wall flashings must be supplied and installed (by others), at the next course above the reglet or, alternatively, the inside of the parapet wall must be completely flashed or cladded.
Metal base flashing is required on all vertical surfaces, walls, curbs, etc. when hot asphalt is used to adhere stripping (flashing) membranes.
15.7 Flashing on Stucco Walls
On stucco-faced walls, only 2-piece flashings are permitted. The upper piece, retaining the stucco, must have a vertical flange to extend behind stucco and building paper. Stucco stops are not considered metal counter flashings.
© RCABC 2021
No reproduction of this material, in whole or in part, is lawful without the expressed permission of the RCABC.