Chapter 22

Roof Plan Components

Introduction• Roof design is considered before the plan

– Designer considers shape, type, and aesthetics as floor plan and elevations are drawn

– Drafter should understand types, pitches, shapes, and materials

Types of Roof Plans• Roof plan

– Used to show roof shape

• Roof framing plan– Usually required for complicated roof shapes– Shows size and direction of construction

members required to frame the roof

Common Roof Terms• Common terms:

– Ridge– Overhangs

• Roof pitch (e.g., slight, gradual, moderate, and steep slopes)

• Sun angle• Overhang size

– Eaves and rakes• Boxed and soffited

eaves

– Cornice– Fascias and barge

rafters

Roof Shapes• Common roof shapes include:

– Flat– Shed– Gable– A-frame – Gambrel– Hip and Dutch hip– Mansard

Roofing Materials• Material depends on:

– Pitch– Exterior style– Cost– Weather

Roofing Materials (cont’d.)• Types of materials:

– Built-up roofing• Felt and asphalt used on flat or low-sloped roofs

– Shingles• Asphalt, fiberglass, and wood • Wood is also used for shakes (thicker shingles with

irregular texture)• Masonite and metal

Roofing Materials (cont’d.)• Types of materials (cont’d):

– Clay and cement tiles• Used for high end homes or risk of fire is extreme

– Metal panels• Provide savings • Speed and ease of installation• Metal is also used for flashing at all levels

Roof Ventilation and Access• Attic is the space formed between ceiling

joists and rafters– Typically provided with vents covered with

1/16" minimum and ¼" maximum screen mesh– Vents must have an area equal to 1/150 of

attic– Area can be reduced to 1/300

• 50% (not more than 80%) of ventilating area is provided by ventilators in the upper portion of space

Roof Ventilation and Access (cont’d.)

• Unvented attics– Area is completely contained in building

thermal envelope– Additional requirements

• Refer to the text

Roof Ventilation and Access (cont’d.)

• Attic access– Drafter must specify how to get in if area is 30

sq ft or more and height is 30" or more– Actual opening is usually shown on floor plan

• Location must be considered when roof plan is being drawn

• Minimum size is 22" × 30" with 30" minimum headroom