(Draft) Notes to TPO Standard - Revision history

James Klassen: /* Notes to Part 13 */

2026-10-22T17:37:07Z

‎Notes to Part 13

James Klassen: /* Notes to Part 13 */

2026-10-22T16:25:46Z

‎Notes to Part 13

James Klassen: /* A-12.3.2.1.(13)(4) Target Patch Seal */

2026-10-22T16:25:16Z

‎A-12.3.2.1.(13)(4) Target Patch Seal

James Klassen: /* A-1.1.3.1. Permitted Roof Systems */

2026-06-22T15:22:08Z

‎A-1.1.3.1. Permitted Roof Systems

James Klassen: /* A-7.1.3.4. Effective Thermal Resistance and Layering */

2026-01-28T15:59:44Z

‎A-7.1.3.4. Effective Thermal Resistance and Layering

James Klassen: /* Notes to Part 13 */

2025-10-31T14:38:04Z

‎Notes to Part 13

James Klassen: /* A-11.1.4.2. Scuppers and Overflows */

2025-10-31T14:35:54Z

‎A-11.1.4.2. Scuppers and Overflows

James Klassen: /* Notes to Part 7 */

2025-10-31T14:33:27Z

‎Notes to Part 7

James Klassen: /* Notes to Part 2 */

2025-10-31T14:30:06Z

‎Notes to Part 2

James Klassen: /* Notes to Part 1 */

2025-10-31T14:28:14Z

‎Notes to Part 1

@@ Line 538: / Line 538: @@
 ===<big><span class="reference">Notes to Part 13</span></big>===
 <div id=A-13.2.1.2.(3)(2)></div>
 ===={{hilite | A-13.2.1.2.(3)(2) Stainless Steel|| 2026-July-1 }}====

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 ===={{hilite | A-13.2.1.2.(3)(2) Stainless Steel|| 2026-July-1 }}====
-Stainless steel is a good product to use when roof penetrations or metal flashings are exposed to constant water, are used in marine environments (salt-water), or are exposed to highly corrosive by-products from industrial sites. Stainless steel is available in two grades for the roofing industry: Grade 304 And Grade 316.
+:Stainless steel is a good product to use when roof penetrations or metal flashings are exposed to constant water, are used in marine environments (salt-water), or are exposed to highly corrosive by-products from industrial sites. Stainless steel is available in two grades for the roofing industry: Grade 304 And Grade 316.
 Grade 304 and 316 stainless steels behave differently because of their molecular structure (explained below). Grade 304 can be thinner than Grade 316, because of differences in ductility. Grade 304 stainless steel is typically less costly than grade 316 stainless, but it is also suitable for applications where formability is desirable.  This is why Grade 304 is permitted for linear metal flashings.  Conversely, Grade 316 stainless steel is the preferred choice for environments that are highly corrosive, where the material will be consistently exposed to or immersed in water, and in applications where superior strength and hardness are required.  Grade 316L has superior corrosion resistance over Grade 316 stainless steel because of its low (L) carbon content.  Therefore, for consistency in RGC requirements, and to improve the corrosion resistance of stainless steel used in the '''''RoofStar Guarantee Program''''', the Standard recognizes only Grade 316L for roof drains, overflows, and penetration flashings.
-Grade 304 stainless steel is perhaps the most common austenitic stainless steel.  This type of stainless steel is characterized by a specific crystal structure called austenite.  The result is a stainless steel that resists corrosion, is highly ductile, and exhibits good welding properties. In addition to iron, grade 304 stainless steel contains a high nickel content (8 to 10.5 percent by weight on average), and a high amount of chromium (18 to 20 percent by weight). It also contains other alloying elements such as manganese, silicon, and carbon.  The high chromium and nickel content is the reason behind grade 304 stainless steel’s excellent corrosion resistance. 304 stainless steel is commonly used in environments where even galvanized carbon steel likely would corrode, or where leaching zinc from galvanized steel may harm water habitats.
+:Grade 304 stainless steel is perhaps the most common austenitic stainless steel.  This type of stainless steel is characterized by a specific crystal structure called austenite.  The result is a stainless steel that resists corrosion, is highly ductile, and exhibits good welding properties. In addition to iron, grade 304 stainless steel contains a high nickel content (8 to 10.5 percent by weight on average), and a high amount of chromium (18 to 20 percent by weight). It also contains other alloying elements such as manganese, silicon, and carbon.  The high chromium and nickel content is the reason behind grade 304 stainless steel’s excellent corrosion resistance. 304 stainless steel is commonly used in environments where even galvanized carbon steel likely would corrode, or where leaching zinc from galvanized steel may harm water habitats.
-Grade 316L stainless steel has high amounts of chromium and nickel, much like grade 304 stainless, and it also contains silicon, manganese, and carbon (in addition to iron). However, grade 316 stainless steel also contains 2 to 3 percent molybdenum (by weight), compared to only trace amounts found in 304 stainless steel. Higher molybdenum content produces a superior corrosion-resistant stainless steel. Grade 316L stainless steel is often considered one of the most suitable choices for marine applications.
+:Grade 316L stainless steel has high amounts of chromium and nickel, much like grade 304 stainless, and it also contains silicon, manganese, and carbon (in addition to iron). However, grade 316 stainless steel also contains 2 to 3 percent molybdenum (by weight), compared to only trace amounts found in 304 stainless steel. Higher molybdenum content produces a superior corrosion-resistant stainless steel. Grade 316L stainless steel is often considered one of the most suitable choices for marine applications.
 <div id=A-13.2.2.1.(4)></div>
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 ===={{hilite | A-13.2.2.1.(4) Coefficient of expansion and securement of linear metal flashings|| 2026-October-31 }}====
-{{hilite | The coefficient of thermal expansion is the mathematical expression of linear movement one can expect of a particular metal when it is exposed to changes in temperature. Alloys will change these properties, which is why it is important to know the metal's composition. || 2026-October-31 }}
+:{{hilite | The coefficient of thermal expansion is the mathematical expression of linear movement one can expect of a particular metal when it is exposed to changes in temperature. Alloys will change these properties, which is why it is important to know the metal's composition. || 2026-October-31 }}
-{{hilite | Because the degree of linear movement increases with flashing length, the ''registered professional'' responsible for designing ''linear metal flashing'' securement should consider anchoring the mid-point of very long flashings to allow for bi-directional expansion. However, each solution presents its own challenges. Affixing flashings at an end or in the middle forces expansion and contraction away from the anchoring point. This must be considered when designing a system of flashings where each length of material is attached to another. || 2026-October-31 }}
+:{{hilite | Because the degree of linear movement increases with flashing length, the ''registered professional'' responsible for designing ''linear metal flashing'' securement should consider anchoring the mid-point of very long flashings to allow for bi-directional expansion. However, each solution presents its own challenges. Affixing flashings at an end or in the middle forces expansion and contraction away from the anchoring point. This must be considered when designing a system of flashings where each length of material is attached to another. || 2026-October-31 }}
 ===<big><span class="reference">Notes to Part 14</span></big>===

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 ====A-12.3.2.1.(13)(4) Target Patch Seal====
-For the target patch membrane to achieve a good seal around the base of the penetration flashing, it must make full contact with the untrimmed surface of the flange; anything less negates the reason for the required flange width, which was instituted to ensure an adequate seal around the circumference of the flashing (See [[TPO Roof Systems Standard#12.2.1.2. General Requirements for Penetration Flashings | Article 12.2.1.2.]] for flashing properties).
+:For the target patch membrane to achieve a good seal around the base of the penetration flashing, it must make full contact with the untrimmed surface of the flange; anything less negates the reason for the required flange width, which was instituted to ensure an adequate seal around the circumference of the flashing (See [[TPO Roof Systems Standard#12.2.1.2. General Requirements for Penetration Flashings | Article 12.2.1.2.]] for flashing properties).
 ===<big><span class="reference">Notes to Part 13</span></big>===

@@ Line 34: / Line 34: @@
 ::*support liveable (amenity) spaces.
-: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 Article 1.1.1.4., "Definitions".
+:The ''finished system surface'' is defined as the top surface of any waterproofing or water-shedding system, inclusive of ballast or overburden.  These materials will displace water and therefore affect the height of ''primary material'' flashing needed to prevent water ingress.  The definition of ''finished system surface'' is illustrated below in '''Figures 1.3.2-1''' and '''1.3.2-2'''.  See also Article 1.1.1.4., "Defined Terms".
 <div class="col-md-12">
 <div class="col-md-6">

@@ Line 374: / Line 374: @@
 <div id=A-7.1.3.4.></div>
-====A-7.1.3.4. Effective Thermal Resistance and Layering====
+====A-7.1.3.4. {{strike| Effective || 2026-January-28 }} {{hilite | Thermal Resistance and Layering|| 2027-February-1 }}====
 :{{hilite | In warm seasons, the roof surface may reach temperatures higher than 85°C (185°F), affecting the performance and stability of some insulation. Consequently, the requirement which limits panel size in single-layer applications ensures that inevitable gaps between adjacent panels are kept to a minimum.  Combining insulation types in a ''roof system'' may help mitigate these temperature swings and the consequence of thermal contraction. The ''Design Authority'' therefore must consider these variables when specifying materials and their installation. || 2023-June-16 }}

← Older revision		Revision as of 14:38, 31 October 2025
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	Grade 316L stainless steel has high amounts of chromium and nickel, much like grade 304 stainless, and it also contains silicon, manganese, and carbon (in addition to iron). However, grade 316 stainless steel also contains 2 to 3 percent molybdenum (by weight), compared to only trace amounts found in 304 stainless steel. Higher molybdenum content produces a superior corrosion-resistant stainless steel. Grade 316L stainless steel is often considered one of the most suitable choices for marine applications.		Grade 316L stainless steel has high amounts of chromium and nickel, much like grade 304 stainless, and it also contains silicon, manganese, and carbon (in addition to iron). However, grade 316 stainless steel also contains 2 to 3 percent molybdenum (by weight), compared to only trace amounts found in 304 stainless steel. Higher molybdenum content produces a superior corrosion-resistant stainless steel. Grade 316L stainless steel is often considered one of the most suitable choices for marine applications.
		+
		+	<div id=A-13.2.2.1.(4)></div>
		+
		+	===={{hilite \| A-13.2.2.1.(4) Coefficient of expansion and securement of linear metal flashings\|\| 2026-October-31 }}====
		+
		+	{{hilite \| The coefficient of thermal expansion is the mathematical expression of linear movement one can expect of a particular metal when it is exposed to changes in temperature. Alloys will change these properties, which is why it is important to know the metal's composition. \|\| 2026-October-31 }}
		+
		+	{{hilite \| Because the degree of linear movement increases with flashing length, the ''registered professional'' responsible for designing ''linear metal flashing'' securement should consider anchoring the mid-point of very long flashings to allow for bi-directional expansion. However, each solution presents its own challenges. Affixing flashings at an end or in the middle forces expansion and contraction away from the anchoring point. This must be considered when designing a system of flashings where each length of material is attached to another. \|\| 2026-October-31 }}

	===<big><span class="reference">Notes to Part 14</span></big>===		===<big><span class="reference">Notes to Part 14</span></big>===

@@ Line 485: / Line 485: @@
 ====A-11.1.4.2. Scuppers and Overflows====
-:{{hilite | The primary function of an overflow is to keep a roof from collapsing when primary roof drains are plugged or cannot drain heavy rainfall.  New and existing buildings should incorporate overflows to handle large rain events.  Refer to the "British Columbia Building Code" and the "British Columbia Plumbing Code" for drain sizing and location requirements. || 2023-June-16 }}
+:{{hilite | The primary function of an ''overflow'' is to keep a roof from collapsing when primary roof drains are plugged or cannot drain heavy rainfall.  New and existing buildings should incorporate overflows to handle large rain events.  Refer to the "British Columbia Building Code" and the "British Columbia Plumbing Code" for drain sizing and location requirements. || 2023-June-16 }}
 <div id=A-11.1.4.3.></div>

← Older revision		Revision as of 14:33, 31 October 2025
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	:{{hilite \| The requirement to use a layer of heat-resistant insulation on top of heat-sensitive insulation is based on a mathematical modeling of the buffering effects of different overlay strategies. While modeling showed some insulation overlay panels reduced some absorbed heat, none reduced heat below the service temperature of the insulation, and none provided sufficient margin to allow for high-heat weather events. Only heat-resistant insulation measuring at least 50 mm (2") thick offered the necessary level of protection to prevent insulation damage. \|\| 2023-June-16 }}		:{{hilite \| The requirement to use a layer of heat-resistant insulation on top of heat-sensitive insulation is based on a mathematical modeling of the buffering effects of different overlay strategies. While modeling showed some insulation overlay panels reduced some absorbed heat, none reduced heat below the service temperature of the insulation, and none provided sufficient margin to allow for high-heat weather events. Only heat-resistant insulation measuring at least 50 mm (2") thick offered the necessary level of protection to prevent insulation damage. \|\| 2023-June-16 }}
		+
		+	<div id=A-7.1.5.2.></div>
		+
		+	===={{hilite \| A-7.1.5.2. Waterproofing Roof Systems on Uninsulated, Vented Wood-Frame Structures \|\| 2026-October-31 }}====
		+	:{{hilite \| Some roofs on older wood-framed buildings (often Multi-Unit Residential Buildings, or MURBs) are still protected by built-up ''roof systems'' (BURs) that have aged past their end-of-service date. Topped with small-sized gravel, these roofs absorb and reflect heat energy that keeps the roof ''deck'' warm and dry, even through cool nights. Buildings of this design are usually insulated between the joists below the roof deck and often, though not always, there is a 'ventilation' cavity between the insulated joists and the underside of the ''deck''. These older buildings are also characteristically air-leaky, carrying water vapour into the roof cavity. However, because of the properties of the old BUR ''roof system'', condensation on the underside of the deck has never been an issue \|\| 2026-October-31 }}.
		+
		+	:{{hilite \| Where condensation and subsequent deterioration of the roof deck has occurred, even when the ventilation meets Section 9.19 of the Building Code, it appears to be associated with replacement roof designs that did not account for the thermal properties of the former BUR roof assembly. Condensation can be a problem in marine climate regions (such as along the British Columbia coast) where higher relative humidity values, especially when combined with the night sky effect, cause condensation on the underside of the roof ''deck'' (See the two studies on asphalt shingle roofs commissioned by BC Housing, with support from the RCABC - [https://www.bchousing.org/publications/Asphalt-Shingle-Sloped-Roofing-Research-Study.pdf Phase 1] and [https://www.bchousing.org/publications/Field-Evaluation-Roof-Treatments-Report.pdf Phase 2]). Therefore, when designing a roof for a new wood-framed building or a replacement ''roof system'' for an existing BUR roof, the ''Design Authority'' should consider the potential for condensation on the underside of the roof ''deck'' and design the new ''roof system'' to prevent it. This may be accomplished by evaluating the effectiveness of ventilation below the deck ensuring it is not obstructed), or by insulating the new roof system above the deck and using darker membranes, but any mitigation strategies such as the addition of above-deck insulation must be carefully considered and calculated by the ''Design Authority'' \|\| 2026-October-31 }}.
		+
		+	:{{hilite \| When the existing roof system cannot be easily removed from the supporting deck (for example, a BUR system that was mopped directly to wood), the ''Design Authority'' should consider the 'recover' option in \|\| 2026-October-31 }} [[SBS Roof Systems Standard#Part 1 - General \|{{hilite \| Part 1 \|\| 2026-October-31 }}]] {{hilite \| of this Standard \|\| 2026-October-31 }}.

	<div id=A-7.2.2.3.></div>		<div id=A-7.2.2.3.></div>

@@ Line 174: / Line 174: @@
 ====A-2.1.5.5. Overlays for Mass Timber Decks====
 :An overlay may be required by the ''manufacturer'' for these types of wood decks to protect membranes from wood sap, deck surface irregularities, and protruding fasteners.
 <div id=A-2.1.7.></div>

← Older revision		Revision as of 14:28, 31 October 2025
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	:Cutting the existing membrane is also necessary to relieve diaphragm-like tension that could distort the new ''roof system'', particularly at the perimeter. It also allows any existing moisture in the roof system to move around and prevents the existing membrane from acting as an intermediate vapour retarder that could adversely affect the performance of the recovered ''roof system''.		:Cutting the existing membrane is also necessary to relieve diaphragm-like tension that could distort the new ''roof system'', particularly at the perimeter. It also allows any existing moisture in the roof system to move around and prevents the existing membrane from acting as an intermediate vapour retarder that could adversely affect the performance of the recovered ''roof system''.
		+
		+	<div id=A-1.1.4.4.(9).></div>
		+
		+	===={{hilite \| A-1.1.4.4.(9) Recovering Membranes in a Protected Assembly \|\| 2026-October-31 }}====
		+	:{{hilite \| When an in-service membrane is demonstrably secure (fully bonded to the roof ''deck'' – adhesion of the membrane for wind uplift resistance must be tested, and the test results submitted to the '''''Guarantor''''' with the request for a Variance), it is blister-free, and it is free of damage, the '''''Guarantor''''' may permit the application of a new membrane directly to the existing membrane, without requiring membrane removal or the application of an intermediate overlay board. \|\| 2026-October-31 }}

	<div id=A-1.3.2.2.></div>		<div id=A-1.3.2.2.></div>