Template:Part 7 (Waterproofing Roofs)

See more information on Insulating the Roof in Division B: Essential Elements.

1 General

1.1 Definitions

Refer to the Glossary for further definitions of key terms used in this Manual.

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

1.2 Design

1.2.1 RoofStar 15-Year Guarantee

All curbs and sleepers that impede drainage or are wider or longer than 1200 mm (48”) must incorporate crickets to provide positive slope to drains.

1.2.2 All Projects

The use of thermal barrier between the roof deck and the insulation is the responsibility of the Design Authority and may be required by the Building and Fire Code having jurisdiction. See also Part 5 DECK and WALL OVERLAYS.
Consult the Building Code having jurisdiction for the minimum required thermal resistance of the roof assembly.
Insulation materials rely on various standards for the determination of thermal resistance, which means that not all data can be easily compared. Furthermore, not all insulation products perform with consistent thermal resistance as temperature changes, and some insulation performance declines with age. The Design Authority is therefore urged to consider the Long-term Thermal Resistance (LTTR) for each product, in relation to its placement within the roof assembly and the anticipated outside and interior climates of the building.
In warm seasons, the roof surface may reach temperatures higher than 85°C (185°F), affecting the performance and stability of some insulation. Combining insulation types in a roof assembly may help mitigate these temperature swings and consequential distortion of the assembly. The Design Authority therefore must consider these variables when specifying materials and their installation.
When heat-sensitive insulations are used in the primary thermal assembly, they must be covered with a heat-resistant insulation at least 50 mm (2”) thick. See also 7.1.2(9) below.
Insulation assemblies with a cumulative thermal resistance greater than RSI-2.64 (R-15) (based on published LTTR values measured at 24°C) must be installed in multiple layers that are offset and staggered (see 7.3 Application). Within that multi-layered assembly, any single layer of insulation may have a thermal resistance greater than RSI-2.64 (R-15) provided no one layer exceeds 60% of the cumulative thermal resistance of the combined assembly of insulation and insulation overlay boards.

See Figure 7.1.
Figure 7.1
Tapered insulation can be utilized to slope the surface of the roof assembly to achieve adequate drainage (see 2.2 Roof Slopes). The thermal resistance of tapered insulation may be used in calculating the overall thermal performance of the roof assembly and may vary depending upon the layout of the sloped insulation package, but this is at the discretion of the Design Authority.
Tapered insulation
1. may be located within the roof system to slope the surface of the roof assembly to achieve adequate drainage (see 2.2 Roof Slopes).
2. may be used in calculating the overall thermal performance of the roof assembly and may vary depending upon the layout of the sloped insulation package, but this is at the discretion of the Design Authority.
3. greater than 150 mm (6”) in thickness shall be installed in multiple soldiered layers.
4. that is heat-sensitive and manufactured to cover the entire roof area (commonly referred to as a full slope or taper package) must be installed beneath at least one layer of flat board heat-resistant insulation with a minimum thickness of 50 mm (2”).
5. used only as crickets to promote drainage over limited areas of the roof
  1. should be manufactured of heat-resistant insulation, but when crickets are manufactured from heat-sensitive insulation they should be covered with a layer of heat-resistant insulation at least 50 mm (2") thick.
  2. may be installed directly over a roof deck, although this is not recommended. See 8.1.1 Design for overlay requirements.
Regardless of average thermal resistance calculations for the roof assembly, drain sumps should be adequately insulated, based on the regional location of the building. See 11.1.2(1) for drain sump design.
Mineral wool insulation panels must be fastened or adhered according to the manufacturer’s published instructions and tested assemblies, but in any event must conform to the following Guarantee Standards, which are summarized as follows:
1. Only bitumen-coated Mineral Wool insulation may be used in the top-most layer of insulation, or may be secured with adhesive.
2. A Non-Coated Mineral Wool base insulation layer is permissible only by mechanically fastening, but may not have additional insulation layers adhered to it.
3. When mineral wool insulation is mechanically fastened, a 12 mm (1/2”) insulation overlay board is required, whether or not overburden is present.
4. Roofs without overburden – an insulation overlay board is not required when bitumen-coated mineral wool insulation is adhered as a single layer, or when it is adhered as the top layer in a multi-layer assembly.
5. Roofs with overburden – mineral wool insulation in a roof assembly that will support an overburden must be overlaid with an insulation overlay board at least 12 mm (1/2”) thick, irrespective of the method by which the insulation is fastened.

Optional combinations are illustrated below (hover over any image and click on the link to expand it):

Figure 7.2
Click here to open in new window Single layer (adhered) Click here to open in new window Single layer (mechanically fastened) Click here to open in new window Double layer (adhered) Click here to open in new window Double layer (hybrid securement) Click here to open in new window Double layer (mechanically fastened) Click here to open in new window Double layer (adhered, with overburden) Click here to open in new window Double layer (hybrid securement,with overburden) Click here to open in new window Double layer (mechanically fastened, with overburden)

2 Materials

Only insulation boards accepted for use in the RoofStar Guarantee Program, and acceptable to the membrane manufacturer, may be used to qualify for a RoofStar Guarantee. This includes insulation used in Tested Assemblies (see 3.2.1 Material Substitution in Tested Assemblies). Specific standards and limitations for commonly used insulation types are listed below. To see the full range of insulation products accepted for the RoofStar Guarantee Program, refer to the full listing of accepted Insulation materials.

All insulation types shall have a minimum compressive strength of 110 KPa (20 psi) when installed without a cover board under mechanically attached membranes.
Polyisocyanurate:
1. Only polyisocyanurate insulation with non-organic facers (e.g. fibreglass) are acceptable for use in the RoofStar Guarantee Program. In addition, manufacturers’ product identification labels are required for all Polyisocyanurate insulation packaging and the date of manufacture must be provided on all product labels.
2. Polyisocyanurate insulation, which is manufactured to various dimensions and board thicknesses, is suitable only for conventionally insulated roof assemblies and may be manufactured in sloped packages, for individual crickets or for full roof area application.
Mineral wool – manufactured to various dimensions and board thicknesses, and may be manufactured in sloped packages, for individual crickets or for full roof area application. Mineral wool insulation is suitable only for conventionally insulated roof assemblies.
Expanded Polystyrene (EPS) – EPS insulation is manufactured in various board dimensions and may be manufactured in sloped packages, for individual crickets or for full roof area application. EPS is suitable only for conventionally insulated roof assemblies.
Extruded Polystyrene (XPS) – XPS insulation is a closed-cell material manufactured in various board dimensions, and is mainly used in a Protected Membrane Roof Assembly. Only Extruded Polystyrene Insulation (conforming to CAN / CGSB-51.20-M87, Type 4) may be used on Protected Membrane Roof Assemblies. For more about PMRAs, see Protected and Modified Protected Roof Systems. See also Part 14 THE ROOF as a PLATFORM.
Material dimensions:
1. The maximum width and length of any adhered insulation panel shall be 1200 mm (4’) (see also 3.3.2 Adhesive Applied and 7.3.2 (4) below).
2. The maximum width and length of insulation boards installed with mechanical fasteners is limited only by the manufacturer.
3. Insulation installed directly over a fluted steel deck must be thick enough to span the flutes under live loads, without risk of cracking or breakage.
4. While minimal insulation panel thicknesses are permissible for some designs, the Design Authority should consider the constructability of the roof system from a material handling perspective. Therefore, when materials are by their nature breakable, the specifier should consider specifying a thicker panel.

3 Application

3.1 General

3.1.1 RoofStar 15-Year Guarantees

See the requirements for a RoofStar 15-Year Guarantee in 7.1.2.1.
An insulation overlay is required for all insulated systems, regardless of the insulation type, and overlays must
1. be at least 6.4 mm (1/4”) thick.
2. possess a compressive strength of at least 690 kPa (100 psi).

3.1.2 All Projects

Insulation must be fastened or adhered to resist the Specified Wind Loads calculated for the roof system. See also Part 3 SECURING the ROOF ASSEMBLY.
Roof system components adhered with two-component low-rise polyurethane foam must be
1. installed immediately in wet adhesive (before a surface skin develops).
2. properly placed and weighted in wet adhesive until cured.
Hot bitumen used to adhere a roof assembly
1. must be applied at minimum rates and temperatures based on the type of product, as published by the material manufacturer and in the RoofStar Guarantee Standards for Built-up Roof (BUR) Systems.
2. may be applied on slopes up to 1/2:12 (for steeper slopes, select a different method of securement).

3.2 Alignment, Sizing and Support

Insulation boards must be firmly supported.
Insulation boards should be square and should make firm, full contact with adjacent panels. Gaps greater than 6 mm (1/4”) around boards must be filled with expanding spray foam.
Insulation board joints must be offset at least 300 mm (12"), both for adjacent layers and for adjacent rows; a minus offset tolerance of 50 mm (2") maximum is permissible (see Figure 7.3). Insulation offsets are not required for
1. sloped insulation boards that are generally installed soldiered fashion to adjacent rows.
2. the first layer of overlay board, installed on top of heat-sensitive insulation, which may be soldiered to facilitate joint taping.
See also 8.3.1 General.

Figure 7.3
Unless specified otherwise by a Tested Assembly or in an engineered specification (see 3.3.3.4.2 Adhesive Applied Materials), the following minimum standards apply to adhesive-applied insulation:
1. The maximum width and length of any adhered insulation panel shall be 1200 mm (4’).
2. The maximum length of any insulation overlay panel shall be 2400 mm (8’).
3. When Extruded Polystyrene insulation is adhered with a two-component low-rise polyurethane foam adhesive, the faces of the insulation board must be roughened by planing to achieve optimal adhesion.
4. Two-component low-rise polyurethane foam adhesive ribbons must be applied
  1. in parallel runs or in a Z-pattern, no more than 150 mm (6”) from any edge of the board and spaced no more than 300 mm (12”) apart.
  2. to a clean, dry and contaminant-free surface.
  3. in ribbon widths specified by the adhesive manufacturer or, in the absence of manufacturer requirements, 19 mm (3/4”) wide.
5. Roof system components adhered with two-component low-rise polyurethane foam must be
  1. installed immediately in wet adhesive (before a surface skin develops).
  2. properly placed and weighted in wet adhesive until cured.
6. Hot bitumen used to adhere a roof assembly
  1. must be applied at minimum rates and temperatures based on the type of product, as published by the material manufacturer and in the RoofStar Guarantee Standards for Built-up Roof (BUR) Systems.
  2. may be applied on slopes up to 1/2:12 (for steeper slopes, select a different method of securement).