Installation Guide

42
roof ventilation
accessories installation
Determining proper
ventilation
For best results, vents must provide
1.5 sq. inches of net free area per
sq. ft. of attic floor area, including
enclosed overhang. (Fig. 1)
Placing proper ventilation
Ideally 50% of the required free
ventilating area should be placed at
the ridge and 25% in each opposing
soffit. Soffit ventilation area may be
slightly larger than ridge ventilation
area. Do not have more ventilation
area in ridge than in the soffit.
The slope/pitch must not be less than
3:12 or greater than 6:12. Wood cant
strips should be used for slopes
outside this range. (Fig. 2)
NOTE: Do not apply generic ridge
vent part on roof hips.
Preparing an existing roof
Remove ridge cap shingles along the
roof ridge.
Snap chalk lines on both sides of the
ridgeline to the dimensions shown in
the illustration at left, depending on
your specific roof construction.
Cut out ventilation opening along the
ridge at chalk lines with ventilation
opening end 12" short of outside
walls, chimneys, or roof protrusion.
Remove cutout portion of sheathing
and shingles, leaving a clean open
slot.
For new construction
Plywood can be set or cut back to the
required dimension leaving a total
opening of 1-1/2". Shingles should
then be installed up to the edge of the
sheathing.
NOTE: Never cut ventilation opening
in overhang.
3
/4"
3
/4"
3
1
/8"
12" Plus
Overhang
Length
3
/4"
3
/4"
1
1
/2"
12" Plus
Overhang
Length
Truss Construction
1
1
/2
"3
1
/8"
Common Framing
Fig. 1
Fig. 2
Preparation