Valley Roof

The Valley roof option is used to calculate valleys for 90 degree intersecting roofs with equal slopes and wall plates at the same height. The heel height, overhang, and ridge and fascia boards for both roofs will be the same. The Blind Valley roof can be used to calculate valleys for roofs with unequal slopes.

When the widths of the major and minor roofs are equal, two valley rafters of equal length will meet in the center at the ridge of the major roof. When the widths of the major and minor roofs are not equal a long valley rafter will run from one inside corner of the intersecting roofs to the ridge of the major roof and a short valley rafter will run from the opposite inside corner of the intersecting roofs to a point on the long valley rafter that it inline with the ridge of the minor roof.

To Calculate a Valley Roof

Select Valley from the Roof Type dropdown list or click on the the corresponding button on the toolbar to calculate a valley roof. The preview window displays a plan view of the valley roof.

Design Tab

Slope

Enter or select the slope of the common rafters.

Note: The slope of the major and minor roofs must be equal.

Major Width

Enter the width of the building covered by the major roof. The major roof is always the wider of the two intersecting roofs.

Minor Width

Enter the width of the building covered by the minor roof.

Overhang

Enter the horizontal overhang of the common rafter including the facsia board.

Note: The overhang will be the same for the both roofs.

Heel Height/Seat Cut

Accept the default heel height and seat cut measurements or override the defaults by locking one or the other and entering a new value.

Note: The heel height will be the same for both roofs.

Lumber Sizes

Enter or select the lumber sizes for the common rafter, valley rafter, ridge board and fascia board.

Fascia Type

Select Plumb Cut or Square Cut from the dropdown list.

Drawing Tabs

Major Common

The Major Common tab displays a dimensioned side view of the major roof common rafter.

Minor Common

The Minor Common tab displays a dimensioned side view of the minor roof common rafter.

Valley

The Valley tab displays a dimensioned side view and top view of the valley rafter for a valley with equal spans.

Short Valley

The Short Valley tab displays a dimensioned side view and top view of the short valley rafter for a valley with unequal spans.

Long Valley

The Long Valley tab displays a dimensioned side view and top view of the long valley rafter for a valley with unequal spans.

Jacks

The Jacks tab displays a dimensioned side view and top view of the valley roof jack rafters. The drawings are representative of all of the jack rafters and do not include the overall lengths which are available on the Layout tab.

Layout

The Layout tab displays a plan view of the valley roof showing the layout and lengths of the jack and cripple rafters. The sheathing angle and jack rafter common difference is also displayed.

The layout toolbar appears below the main toolbar when the Layout tab is selected and contains options that affect the layout of the jack and cripple rafters.

Spacing

Select an on center spacing from the dropdown list.

Major Last Common / o.c. from intersection

The "Major Last Common" input field and the "o.c. from intersection" checkbox field control next to it control the layout of the major roof jack and cripple rafters.

When the "o.c. from intersection" checkbox is checked the value in the "Major Last Common" field is calculated to layout the jack rafters on center from the center of the valley and the input field is disabled.

When the "o.c. from intersection" checkbox is unchecked, the "Major Last Common" input field is enabled with the value calculated for the "o.c. from intersection" option as the default value. The layout of the jack rafters can be adjusted in either direction by increasing or decreasing the value in this field until the desired layout is achieved.

Minor Last Common / o.c. from intersection

The "Minor Last Common" input field and the "o.c. from intersection" checkbox field next to it control the layout of the minor roof jack and cripple rafters.

When the "o.c. from intersection" checkbox is checked the value in the "Minor Last Common" field is calculated to layout the jack rafters on center from the center of the valley and the input field is disabled.

When the "o.c. from intersection" checkbox is unchecked, the "Minor Last Common" input field is enabled with the value calculated for the "o.c. from intersection" option as the default value. The layout of the jack rafters can be adjusted in either direction by increasing or decreasing the value in this field until the desired layout is achieved.

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