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# Roof Framing

### Run

Run can be calculated as:

R = S / 2                        (1)

where

R = run (ft, m)

S = span (ft, m)

#### Example - Run

The run of a roof with 60 feet span is

R = (60 feet) / 2

= 30 feet

### Gable Height

Gable height can be calculated as

GH = R VR                       (2)

where

GH = gable height (ft, m)

R = run (ft, m)

VR = vertical rise (in/ft, cm/m)

### Example - Gable Height

The Gable Height of a roof with 30 feet run and vertical rice 6 inches per foot, can be calculated as

GH = (30 feet) (6 inches/foot)

= 180 inches

= 15 feet

### Gable Area

Gable Area can be calculated as

GA = GH R                        (3)

where

GA = gable area (sq.ft, m2)

GH = gable height (ft, m)

R = run (ft, m)

.

### Roof Slope

Roof slope is the ratio between the vertical rise and the horizontal run:

RS = y / x                      (4)

where

RS = roof slope

y = vertical rise (in, m)

x = horizontal run (in, m)

In the United States, slope is typically given in inches per 1 foot or as a ratio of inches per 12 inches and is often referred to with units of "pitch". Ex.

4 in 12

or

4 pitches, 4:12 pitch

In metric countries it is common to use degrees or 10 or 100 as denominator. Ex.

21.8%

or

4:10

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Typical tolerances for floors, walls, columns and more.

### Chimneys - Roof Termination

Chimneys and single wall vents roof termination.

### Horizontal Roof Rafters - Maximum Spans

Douglas Fir in horizontal roof rafters and maximum spans.

### Moisture Transport through Walls and Roofs

Moisture will flow through a building wall or roof if the vapor partial pressure is higher on one of the sides.

### Rainfall Draining of Roof Areas and Vertical Downspouts

Capacities of vertical downspouts when draining roof areas in rainfall.

### Rainfall on Roofs and Gutter Slopes

Draining of roof areas and recommended gutter slopes

### Roofing Materials - Weights

Weight calculator for roofing materials.

### Transmission Heat Loss through Building Elements

Heat loss through common building elements due to transmission, R-values and U-values - imperial and SI units.

### Walls - No. of Studs

Calculate required number of studs in a wall.

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