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A measured roof framing plan is a top-down structural diagram illustrating the skeleton that supports the roof covering. This technical view details the layout, dimensions, and specifications of all structural members including rafters, trusses, ridges, and joists.
The roof framing plan identifies the size and direction of every component within the roof's structural system. The diagram includes the placement of beams, purlins, and bracing. It focuses on the physical arrangement of the load-bearing framework, specifying the exact dimensions of the internal members rather than the exterior roof shape. In a Roof Framing Plan:
Rafter Layout: Clearly indicate the direction and location of common rafters, hip rafters, jack rafters, and valley rafters.
Truss Layout: If using engineered trusses, provide a layout plan showing truss type, location, and spacing.
Ridge Board/Beam: Location of the highest horizontal member where rafters meet.
Ceiling Joists/Ties: Layout of horizontal joists that tie opposite rafters together to prevent wall spreading.
Collar Ties: Short horizontal members placed in the upper third of the rafters for reinforcement.
Purlins and Bracing: Horizontal beams providing intermediate support to long rafter spans, along with vertical struts and permanent bracing details.
Beam and Header Locations: Positions of beams needed for vaulted ceilings or special supports.
Spacing Dimensions: Clearly state "O.C." (on-center) spacing for rafters or trusses (e.g., 16" or 24" O.C.).
Member Sizes: Specify dimensions of lumber (e.g., or rafters).
Overhang/Eave Dimensions: Accurate measurements from the exterior wall face to the fascia board.
Roof Pitch/Slope: Indicators (e.g., ) for each roof plane to guide proper slope and structural strength.
Wall Plate Dimensions: Dimensions for top plates upon which the roof framing rests.
Hardware and Connectors: Specific locations for hurricane ties, joist hangers, and seismic straps.
Bird's Mouth Cuts: Detail showing how rafters sit on the wall top plate.
Framing Around Penetrations: Detailed framing for chimneys, skylights, and roof vents.
Sheathing Specifications: Material type and thickness for roof decking.
Roof Outline: The outer perimeter of the roof, typically shown in relation to the building walls below.
Title and Scale: Clear identification (e.g., "Roof Framing Plan - 1/4" = 1'-0"").
Structural Notes: Information regarding wood species, grade, and design loads (snow, wind, dead load).
Reference Details: Callouts for detailed sectional drawings of eaves, ridges, or complex connections.
Line Weights: Use lighter, dashed lines for walls below and heavier lines for the roof framing members to make the plan readable.
View: The drawing is a "top-down" view, as if looking through the roof, to show the structural skeleton.
Consistency: Cross-verify with the floor plan to ensure the roof sits correctly on the bearing walls.
Structural Components: Detailed layouts for trusses, rafters, purlins, ridge boards, and collar ties.
Dimensions and Spacing: Exact measurements and spacing for all structural members.
Material Specifications: Identification of lumber sizes, plywood thickness, and hardware required.
Roof Geometry: Shows roof pitches, slopes, hip/valley beams, and overhang details.
This plan serves as a guide for builders to ensure the roof is structurally sound and capable of supporting loads like snow or wind. It ensures that structural members connect correctly to the wall plates.
