After the roof system is selected and the specifics of the system (such as deck type, insulation type(s) and thickness, fastener patterns, and warranty requirements) are developed, it is necessary for the roof designer to determine what details are needed and to design the details so that they are suitable for the project conditions.
Roof Plan: A roof plan should be drawn to scale and be sufficiently large to adequately convey information. It should show all penetrations and all expansion, seismic and area divider joints. The slope directions and approximate amount of slope should also be shown. The different wind uplift areas (field, perimeter and corners) should also be shown and dimensioned. References to all penetrations, roof edges and roof-to-wall details should also be indicated on the plan. (Note: For some standard details such as plumbing vents and roof drains, rather than include the detail on the drawings, referencing the manufacturer’s detail in the specification is typically sufficient unless project conditions require enhancement to the standard detail). An example roof plan is shown in the Typical Roof Plan Layout detail below. If a manufacturer’s standard detail is referenced, the exact detail needs to be appropriate for the condition.
Details: Details should be drawn to scale and should be sufficiently large to adequately convey the information. Illustrating details in section typically suffices. However, with complicated details, an isometric drawing may be needed.
At parapet and roof-to-wall details, the low-point of the roof should be drawn and a dashed line placed at the high point if the roof elevation varies. See Parapet Wall Schematic detail below.
After details have been drawn, it is recommended that they be reviewed by the specified manufacturer(s) prior to bidding. Care should be taken to avoid drawing manufacturer-specific details that can only be met by a single manufacturer, unless a proprietary specification is intended.