Roof Design

Topics of Discussions Roof types Roof construction terms Slope vs. Pitch Roof terminology Metal framing connectors Roof ventilation

Basic Shapes Gable Roof Hip Roof Flat Roof Shed Roof Gambrel Roof Mansard Roof A-Frame Roof

Basic Shape Gable Roof Slopes in from two sides Gable ends allow for attic venting

Basic Shape Hip Roof Slopes in from all four sides No gable ends for vent attic

Basic Shape Flat Roof Requires a built-up roof Slight slope of 1/4” to 12” helps drainage

Basic Shape Shed Roof 3/12 or more slope Can be shingled Economical like flat roof

Basic Shape Two slopes from two sides Traditional “Barn” shape Gambrel Roof Two slopes from two sides Traditional “Barn” shape 2nd story under roof

Basic Shape Mansard Roof Two slopes from two sides Top nearly flat 2nd story within the roof area

Basic Shape A-frame Roof Steep for snow country Roof and ceiling same structure

Roof Construction Basic terms: slope/pitch--incline of roof roof member terms--structure of roof eave/cornice--detail showing wall to roof const fascia--visible member attached to end of rafters ridge--top of roof sheathing--material covering the top of rafters rafter/ceiling joist--structure framing of roof soffit--underneath side of roof overhang vents--in soffit, allows air circulation in attic

Slope Vs. Pitch Slope = Rise/Run Pitch = Rise/Span Text book error (noted as pitch symbol) Slope = Rise/Run expressed as a ratio always a base of 12 placed on dwg. Slope symbol 12 4 Pitch = Rise/Span expressed as fraction reduce to smallest fraction not placed on drawing, helpful to carpenter

Roof Terms Span Distance across the building

Roof Terms Run 1/2 the distance across the building (1/2 span distance)

Roof Terms Rise The distance the roof rises (distance from the square of house to ridge)

Roof Terms Pitch The fraction of the rise over span

Roof Terms Slope Slope is stated as a ratio of rise over run with run always as 12

Slope vs Pitch vs Angle Slope Pitch Angle 3:12 1/8 14°0’0” 3:12 1/8 14°0’0” 4:12 1/6 18°30’ 5:12 5/24 22°30’ 6:12 1/4 26°30’

Roof Member Terminology

Metal Framing Connectors Keeps structural members from separating