View source for Template:Part 5 - PVC

__NOTOC__
==General==
==={{hilite | Definitions|| 2021-June-30 }}===
{{hilite |Refer to the|| 2021-June-30 }} [http://rpm.rcabc.org/index.php?title=Glossary '''Glossary'''] {{hilite |for further definitions of key terms used in this ''Manual''.  See also '''2.1.1 Definitions'''.|| 2021-June-18 }}.

==={{hilite | Design|| 2021-June-18 }}===
<ol>
<li>When a supporting ''deck'' structure or ''wall'' is unsuitable for the application of roofing materials, it must be covered with a {{hilite | RoofStar-accepted|| 2021-June-18 }} overlay.  See '''2.1''' ('''3''') for supporting {{hilite | ''deck'' and ''wall''|| 2021-June-18 }} surface requirements.
<li><span class="reference">A roof ''deck'' overlay (also called a system underlay) is installed as part of the ''roof system'', on the top surface of the roof ''deck'' but beneath the roofing materials. These products are most commonly affixed to steel ''decks'' to provide a level surface for the roof membrane, to support air or vapour control layers, or to serve as a thermal barrier between the roof deck and combustible insulation.  Roof ''deck'' overlay materials may also be applied to other types of supporting ''deck'' structures, depending on the roof design criteria</span>.
<li><span class="principles">When a roof design includes any type of ''overburden'', the ''deck'' overlay on steel ''decks'', or on wood ''decks'' less than 25 mm (1”) thick, should be at least 16 mm (5/8”) thick, in order to stiffen the supporting surface and reduce ''deck'' deflection</span>.
</li></ol>

==Materials==
<ol>
<li>''Deck'' and ''wall'' overlays must be suitable for, and compatible with, any membrane or panel application.  Plywood, measuring at least 12.7 mm (1/2”) in thickness, is acceptable as a ''deck'' or ''wall'' overlay; for roofs supporting an ''overburden'', the plywood must be at least 16 mm (5/8”) thick.
<li><span class="principles">Self-adhering or adhesive-applied materials should be considered as alternatives to torch-applied membranes when the substrate to which they will be applied is combustible, or when nearby structures, openings or materials present a fire hazard.</span>  In the alternative, a suitable separation or overlay material as protection from open flame is acceptable.  The application of materials to a combustible surface, using a torch, is strictly prohibited.
<li>When the Code having jurisdiction requires a thermal barrier, an accepted ''deck'' overlay must be specified and installed.
<li>''Walls'' that require resurfacing for membrane application must be covered with an accepted wall overlay.  See Accepted [http://rpm.rcabc.org/index.php/Wall_Overlays '''Wall Overlays'''].
<li>Fasteners used to secure ''deck'' overlays must be corrosion-resistant or resin-coated, and must be used together with plates when specified or listed in a ''Tested Assembly'' report.
<br>
<br>
See also Accepted [http://rpm.rcabc.org/index.php/Roof_Deck_Overlays '''Roof Deck Overlays'''].
</li></ol>
<div id="DECK_WALL_OVERLAYS"></div>
==Application==
===General===
<ol>
<li>''Deck'' overlays must be
<ol>
<li>fully or intermittently supported along all edges by the ''deck''.
<li>installed in a staggered pattern (offset) 300 mm (12") from adjacent board rows.  A minus offset tolerance of 50 mm (2") maximum will be permitted to compensate for variance in the manufacturer's tolerance of differing board widths and lengths.
<li>affixed to the ''deck'' with either or both
<ol>
<li>mechanical fasteners.
<li>proprietary polyurethane foam adhesives acceptable to the primary ''roof system'' manufacturer to meet or exceed the requirements set out in '''Part 3 SECURING the ROOF ASSEMBLY'''.
</li></ol>
<li>independently fastened to the ''deck'' in keeping with either of the following:
<ol>
<li>at least four (4) fasteners (with plates) per 1200 x 2400 (4’x8’) sheet, or
<li>as required by a ''Tested Assembly'', when part of a '''PARS''' or '''MARS''' ''Conventionally Insulated System''.
</li></ol>
</li></ol>
<li>''Wall'' overlays
<ol>
<li>must be applied to existing sheathing, where existing sheathing is not an acceptable substrate.
<li>may be mechanically fastened or adhered.
<li>may be replaced with an accepted material.
</li></ol>
</li></ol>
<div id="DECK_OVERLAYS"></div>
===Steel Decks===
<ol>
<li>RoofStar-accepted ''deck'' overlay boards used as a thermal barrier to achieve a specific fire rating must conform to the applicable code and insurance requirements for the ''roof system''. 
<li>When the ''roof system'' is uninsulated, the ''deck'' must be overlaid with at least one 12.7 mm (1/2”) thick layer of either
<ol>
<li>moisture resistant gypsum core ''deck'' overlay board.
<li>plywood.
</li></ol>
</li></ol>

===Concrete Decks===
<ol>
<li>A ''deck'' overlay board is not mandatory on a concrete ''supporting deck''.
</li></ol>

===Wood Decks===
<ol>
<li>A mechanically fastened overlay board is required for any ''deck'' structure that does not meet the ''deck'' fastening criteria set out in '''2.3.3.3 Wood'''.
<li>Regardless of the type of ''deck'' overlay selected by the ''Design Authority'', the overlay boards shall be installed in a staggered pattern (offset) 300 mm (12") from adjacent board rows.  A minus offset tolerance of 50 mm (2") maximum will be permitted to compensate for variance in the manufacturer's tolerance of differing board widths and lengths.
<li>Adhering a primary roof membrane directly to a wood ''deck'' is not acceptable.
<li>Notwithstanding Sentence 3 above, a self-adhered air or vapour control layer may be applied to a supporting wood ''deck''.
<li>Mechanically fastened or loose-laid membranes applied directly to a supporting wood ''deck'' structure do not require a ''deck'' overlay board unless specified by the membrane manufacturer.
</li></ol>
<div id="WALL_OVERLAYS"></div>
===Walls===
<ol>
<li>Where the ''wall'' surface is unsuitable to receive a membrane, it must be covered with an accepted overlay panel material {{hilite | (refer to '''Division C: Accepted Materials''' in this ''Manual'')|| 2021-June-30 }}.
<li>''Wall'' overlay panels must be
<ol>
<li>mechanically fastened with screw fasteners spaced no more than 300 mm (12”) O.C. vertically and horizontally, in alignment with structural supports, and placed 
<ol>
<li>at the perimeters.
<li>at the corners.
<li>in the field.
</li></ol>
<li>adhered with a polyurethane adhesive, applied with a continuous z-patterned ribbon spaced no less than 300 mm (12”) apart.
</li></ol>
</li></ol>