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Draft Template:Part 1 (Waterproofing Roofs - Single Ply) - RCABC Roofing Practices Manual
Draft Template:Part 1 (Waterproofing Roofs - Single Ply)
means a System in combination with its supporting deck structure (adapted from ASTM D6630-08 Standard Guide for Low slope Insulated Roof membrane Assembly Performance.
3.1 RoofStar 15-Year Guarantee
To qualify for a RoofStar 15-year (Waterproofing Roofs) Guarantee, each Project must be designed and constructed in compliance with both the RoofStar Guarantee Standards and the membrane manufacturer’s 20-year System Warranty standards.
Where enhanced roof system securement is required by the manufacturer, which may exceed the securement required in a Tested Assembly, an Assembly with Proven Past Performance or a custom-engineered securement, the higher securement requirements must be complied with.
Designing a good roof begins with the end in mind and an answer to the essential question, “What purpose will the roof serve?” For example, the roof may
simply weatherproof the building interior.
provide a location for building equipment and services.
support liveable spaces.
Each of these functions may limit the choice of membrane assembly.
There are four principal waterproofing assemblies used on roofs:
Uninsulated Systems(insulation may be installed beneath the deck).
Conventionally Insulated Systems (sometimes referred to as Compact Roofs).
Protected Membrane Roof Systems (also referred to as “inverted”).
Modified Protected Membrane Roof Systems.
Of course, sometimes the roof deck influences these choices. Regardless of the Design Authority’s starting point, knowing where you are going is the beginning of a successful design.
Regardless of the system type, the Finished Waterproofing System is defined by whatever is placed on the membrane, which may be insulation, ballast, pavers or overburden. These materials will displace water and therefore affect the height of membrane flashing needed to prevent water ingress. The definition of Finished Waterproofing System is illustrated below in Figures 1.3.2-1 and 1.3.2-2. See also 1.2 Definitions.
Figure 1.3.2-1 (Conventionally Insulated Waterproofing System)
Figure 1.3.2-2 (Protected Membrane Roof System)
3.2.1 Conventionally Insulated Waterproofing Systems
In a Conventionally Insulated Waterproofing System, the membrane is the final layer, exposed to the weather. It protects the other roofing components, including insulation, from exposure to water, wind and other weather conditions. 'Conventionally Insulated Waterproofing System are classified in this Manual by three different methods of attachment (securement) to the roof deck:
Mechanically Attached Roof Systems (MARS)
Partially Adhered Roof Systems (PARS)
Adhesive Applied Roof Systems (AARS)
More about these three systems is offered in 3 SECURING the ROOF ASSEMBLY.
3.2.2 Protected and Modified Protected Membrane Roof Assemblies
NOTE: See more information on Protected and Modified Protected Roof Systems in Essential Elements.
In a Protected Membrane Roof System (or Protected Membrane Roof Assembly, also called PMRA) the membrane is applied directly to the supporting deck structure or the deck overlay (as required and/or specified), and protected from the elements, and from damage, with insulation and an overburden. In this way, the membrane functions both to waterproof the roof and control air or vapour. Only RoofStar-accepted Extruded Expanded Polystyrene, or XPS, (conforming to CAN / CGSB-51.20-M87, Type 4) is acceptable for a PMRA. XPS is water-resistant (i.e. resistance to water absorption, moisture transfer, and capillary action), freeze-thaw cycling resistant, and possesses a high compressive strength. If a drainage layer is specified, it is typically installed between the membrane and insulation. An additional drainage layer may be installed above the insulation, together with a filter fabric mat and ballast or overburden. These three components - a drainage layer, filter fabric and ballast - promote controlled drainage, resist infiltration of contaminants, resist the lifting forces of wind, and counteract the natural buoyancy of the insulation.
PMRAs are the required roof assembly design for certain types of overburden. See 14.1.2 Design for RoofStar Guarantee Standards.
3)	A Modified Protected Membrane Roof System (or Modified Protected Membrane Roof Assembly, also called MPMRA) is similar to a PMRA except that a layer of insulation is installed underneath the membrane as well as on top. This may offer cost savings as only the top layer of insulation requires ballast and the bottom layer (mechanically fastened or adhered) need not be Extruded Expanded Polystyrene and may be tapered to provide slope. As a general rule, two-thirds or more of the total thermal resistance (RSI or R value) should be above the membrane, but in all cases the Design Authority should perform the required psychrometric calculations before designing a roof system.
3.3 Accessibility for Maintenance
3.3.1 RoofStar 15-Year Guarantee
On all new construction Projects, where external access is not provided, all roofs with a field elevation greater than 7500 mm (25’) above grade must incorporate safe, appropriate access to the roof, for example by incorporating stairs and a doorway or a properly located roof hatch. These requirements are recommended for existing buildings to facilitate maintenance and ongoing performance reviews.
3.3.2 All Projects
While the RoofStar Guarantee Standards pertain to the design and construction of a leak-free roof, accessible design is still critical since a roof must be regularly maintained. Therefore, while the following list is not exhaustive, the Design Authority is urged to consider these guiding principles when designing a roof Project.
All roofs with a field elevation greater than 7500 mm (25’) above grade should incorporate access to the roof by stairs and a doorway or with a properly located roof hatch.
Any hatch, ladder or mechanical unit should be located a sufficient distance away from the roof edge (setback zone) so that other fall protection measures are not required by those using or accessing this equipment. When it is not possible to situate a hatch, ladder or mechanical unit outside the setback zone, guard rails should be designed for the roof edge to provide additional fall protection for those using or accessing such equipment.
Each roof should be designed to provide safe access for maintenance of roof drains, corners or mechanical equipment, where the roof is at least 3 m (10’) above the surface of the ground, or where a hazard to a person exists, should a fall be possible. This principle also applies to roof areas intended for regular occupancy. Therefore, provide fall protection in compliance with the Building Code having jurisdiction, and with the Workers Compensation Act Regulations, by designing appropriately located
tall parapets.
tie-off anchors.
3.4 Waterproofing Integrity Scans and Electronic Leak Detection
An integrity scan is performed after the installation of the waterproofing roof system, before any overburden, equipment or amenity space is installed on top of it. An integrity scan typically uses low-voltage electrical current to detect even the smallest breaches in the roof membrane, but some waterproofing materials may require the use of other technologies in order to verify the roof system’s integrity. Therefore, Design Authority should specify the appropriate technology, keeping in mind the limitations of each scan and detection methodology, and of the membranes that are specified.
Electronic Leak Detection (ELD) utilizes low-voltage electrical current, typically conducted through wires installed in a grid pattern, and are used in response to a leak, to isolate its location in order to minimize investigation time and material removal. This can benefit a building owner who will have to bear the costs of demolition or overburden removal when the standard limits of coverage afforded by the RoofStar Guarantee are exceeded by the Project design and construction. ELDs may be passive (installed but not monitored) or actively monitored (by the installer, through real-time data collection).
Flood testing (as an alternative to an integrity scan) is not recommended. When flood testing is specified, testing shall be conducted prior to installation of insulation and roof coverings, and must be performed to ASTM D5957.
Neither an integrity scan nor an Electronic Leak Detection (ELD) system are considered Accepted Materials, but firms that provide these services are nevertheless specifically recognized and approved by the RoofStar Guarantee Program.
An integrity scan is required for some Projects (see 1.6 RoofStar Guarantee: Coverage and Limitations), but is nevertheless strongly recommended before the completed roof assembly is covered with ovall Waterproofing Systems installed at grade, and while it is optional for Waterproofing Systems on roofs, installed electronic leak detection is strongly recommended.
for Projects where multiple trades will have access to a roof that is under construction and completed, in order to identify breaches in the waterproofing membrane in a timely way and avoid future costly delays.
when the roof assembly protects a sensitive occupied space (i.e. data centres, hospitals, critical infrastructure).
when the roof supports any type of Overburden, equipment or living (amenity) space.
When Electronic Leak Detection is specified, it should provide detection capabilities for the entire waterproofing, and should extend at least 50 mm (2") vertically from the water plane at
any point along the entire deck perimeter.
3.5 Hot Works: Design
pre-approve alternate applications already written within the Manual when the specified application is deemed to be fire sensitive by the Contractor as part of the risk assessment process.
See also 1.4.3 Hot Works: Contractor Requirements.
4.1 New Construction
4.2 Replacement Roofing and Additions
As a roof ages, is neglected or is damaged, it may lose its ability to perform reliably and effectively, necessitating replacement. Replacement roofing, also referred to as "re-roofing," whether made in whole or in part, should be undertaken with the Quality Assurance and Quality Control provided for under the RoofStar Guarantee Program. Regardless of the approach to replacement roofing, the existing deck structure must meet the pullout resistance rating for mechanical fasteners and must be capable of supporting all dead and live loads. Furthermore, the deck must be capable of supporting any additional dead loads of the new roof system.
Three types of replacement roofing are contemplated and permitted (with varying degrees of limitations and conditions) under the RoofStar Guarantee Program:
System Replacement - removal and replacement of all roof system components, except for the supporting deck structure.
Membrane Replacement – removal and replacement of the roof membrane, while retaining existing roof system components (i.e. insulation, ballast).
Recovering - installation of a new membrane over an existing membrane, while retaining some or all of the other roof system materials (NOTE: Recovering is permitted only with a written Variance issued by the RoofStar Guarantee Program).
Qualifying and construction conditions and limitations for each of these replacement options are described below. Other conditions and limitation may be determined by the RoofStar Guarantee Program administration subject to the nature and specifications of the Replacement Roofing Project.
4.2.1 System Replacement
Roof system replacement means the complete removal and replacement of all roof system and metal flashing materials, exclusive of the air or vapour control layers (see 1.4.2.1 (2) below). Only new replacement materials are permissible. The design of the replacement roof system, and the installation of new materials, must conform to the RoofStar Guarantee Standards for new roof construction, unless expressly varied elsewhere in this Standard (see, for example, alternate slope requirements and recommendations in 2.2.3 Replacement Roofing) .
Subject to the requirements in 6 AIR and VAPOUR CONTROLS, the decision to reuse and repair an existing air or vapour control layer remains the responsibility of the Design Authority.
System replacement Projects that conform to the material requirements and standards published in this Manual qualify for all types of a RoofStar Guarantee.
4.2.2 Membrane Replacement
4.2.2.1 RoofStar 15-Year Guarantee
In addition to the General Requirements for Membrane Replacement outlined below, a Project designed to qualify for a RoofStar 15-year Guarantee must
be supported by the following, submitted in report form to the Guarantor for review and consideration prior to tender:
moisture survey scan performed by a qualified person.
at least three (3) cut tests for roof areas up to 20,000 sf (200 squares), or one (1) cut test for every 2000 sf (20 squares), whichever is more.
one (1) cut test for every 3000 sf (30 squares) of roof area that exceeds the first 20,000 sf (200 squares).
one (1) cut test for each small roof area measuring no more than 200 sf (2 squares).
incorporate new insulation overlays in keeping with the requirements published in Part 8 INSULATION OVERLAYS.
4.2.2.2 General Requirements
Membrane replacement is a partial roof system replacement, limited to the membrane or materials adhered to the membrane. A written Variance is not needed for this type of Project, but for membrane replacement to qualify for a RoofStar Guarantee,
the Design Authority must be certain the existing roof system is properly secured to the existing deck structure (see Part 3 SECURING the ROOF ASSEMBLY).
the existing roof system must be demonstrably dry and free of any wet materials (wet materials must be replaced, in order to qualify for a RoofStar Guarantee).
the existing field membrane must be removed and replaced with a new insulation overlay board and a new membrane.
existing membrane flashing must be removed and replaced with new materials.
the design must comply with the RoofStar Guarantee Standards for new roof construction.
4.2.3 Recovering
Recovering - installing a new membrane over an existing membrane - is permitted in certain circumstances for a five (5) or ten (10) year RoofStar Guarantee, though it is not a recommended practice and will limit the scope of coverage for the RoofStar Guarantee. Recovering does not qualify for a 15-year RoofStar Guarantee*.
Qualifying for a RoofStar Guarantee is subject to the Conditions and limitations listed below and is permitted only with a written Variance issued by the Guarantor. A RoofStar Guarantee issued for a recovered roof is limited strictly to the value of new roof system materials; existing materials that remain in place beneath new materials do not qualify for coverage under the RoofStar Guarantee.
4.2.3.1 Recovering: Project Qualifications
Any Variance permitting roof recovering must be applied for in writing by the Design Authority, addressed to the RoofStar Guarantee Program prior to the tendering of documents. To qualify for a Variance, the following conditions must be met and confirmed in the written application:
The new roof system must be properly secured to the existing deck structure (see Part 3 SECURING the ROOF ASSEMBLY).
The existing roof system must be distinct and physically separate from other roof areas.
The request for a Variance must identify the type of roof system - Conventionally Insulated, Protected Membrane Roof System or Modified Protected Membrane Roof System.
Conventionally Insulated Systems only: The existing roof system must be independently surveyed by qualified professionals using calibrated moisture detection equipment and cut tests, and the resulting survey shall be formally documented for review by the RoofStar Guarantee Program administration. The following requirements for cut tests apply, based on roof area. All cut tests shall be independently documented for review by the RoofStar Guarantee Program:
Where the roof has been constructed with a structurally sloped deck, at least 50% of the required cut tests shall sample roof areas in or near valleys, and areas; samples shall also be taken near roof drains.
Where the roof has been constructed with a structurally flat deck, samples shall be taken near roof drains and in a random pattern across the roof.
All cut tests for existing SBS-modified membrane roof systems shall be performed to ASTM D7636/D7636M, 11 Standard Practice for Sampling and Analysis of Modified Bitumen Roof Systems.
Existing conventionally insulated roof systems constructed with Expanded Polystyrene insulation (EPS) may qualify for a RoofStar Guarantee, subject to the General Conditions and Limitations below.
4.2.3.2 Recovering: General Conditions and Limitations
In addition to the RoofStar Guarantee Standards found in this Manual, the following additional requirements and conditions apply:
All wet material identified by either the independent moisture detection survey or through cut tests shall be
specified for removal.
removed in the course of construction.
The existing membrane on a Conventionally Insulated System must be cut through
in a grid pattern measuring no larger than 6m x 6m (approximately 20' x 20').
around the perimeter of the roof area, no more than 0.2 m (8") from the edge.
A grid-cut field membrane must be overlaid with a mechanically attached insulation overlay board acceptable to the RoofStar Guarantee Program; notwithstanding this requirement, only non-organic and moisture-resistant overlay boards may be used in the Project.
When Expanded Polystyrene insulation (EPS) is present in an existing roof system, the existing membrane must be overlaid with at least one layer of 50 mm (2”) mineral wool or polyisocyanurate insulation, in combination with a RoofStar-accepted insulation overlay board (as required).
New membranes must be properly secured to the underlying roof assembly.
Only new strip-in flashings for roof penetrations are acceptable for a RoofStar Guarantee; existing flashings are not permitted.
Only new roof drains are acceptable for a RoofStar Guarantee, and under no circumstances shall existing roof drains be reused. Cast-iron roof drains in usable condition are exempted from this Standard (see 11.1.2.2(3)).
Only new linear metal flashings are acceptable for installation at perimeters or at membrane terminations, and under no circumstances shall existing linear metal flashings be reused.
4.2.4 Tie-ins and Additions to Existing Roofing
Where a new roof adjoins and ties into an existing roof, the two areas must be isolated and separated by a curb joint securely attached to the structure and waterproofed in keeping with the requirements in 2.5 Control Joints and Part 10 PERIMETERS and WALLS.
If Project conditions do not allow for a curb joint, the Design Authority must obtain a written Variance from the Guarantor that permits the elimination of curb joints. Application for a Variance must include design specifications and construction details showing a positive water cut-off that fully isolates the existing roof from the new roof. In the absence of a curb joint, the new roof system must be easily distinguishable from the existing roof system.
4.3 Hot Works: Contractor Requirements
5.1 Contractor Qualifications
Supervision and installation of a RoofStar-guaranteed Waterproofing System may be conducted only by established employees of Contractors, and every Project must be supervised by a Journeyperson employee who holds a valid ticket. In keeping with RCABC Membership policy, a Journeyperson may supervise a maximum of three (3) apprentices and/or three (3) labourers (ref. RCABC Policy A-248, Rev. 5 April 2019).
6 RoofStar Guarantee: Coverage and Limitations
Overburdens may be installed on ca Conventionally Insulated Waterproofing System or Protected (“inverted”) Membrane Roof Assembly, but not all designs are suitable for any type, size or depth of Overburden (see Part 14 THE ROOF as a PLATFORM). The RGC recommends that a roof supporting overburden be designed and constructed as a Protected Membrane Roof Assembly. The RoofStar Guarantee may be void if a roof is designed and constructed with Overburden that exceeds the capabilities of a Conventionally Insulated Waterproofing System.
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