Snow breaks on a typical shingled roof are placed in groups of three horizontal rows. The first three rows of snow breaks are usually placed about 15 inches up from the eave.
This is often about two rows of shingles. Place the first row beginning at the out wall or outer-most roof support and place the snow breaks about 24 inches apart.
Stagger the second row about 12 to 15 inches up from the first row. The third row is placed exactly as the first row.
The remaining roof area should not require snow guard placement unless you're in a region that accumulates extreme amounts of snow. If you require a second group of snow breaks, begin 6 to 8 feet up from the third row of the first group and place the guards in the same way as you did the first group.
Eaves and Doorways
The first row of snow breaks should be placed above the outer wall or the outer-most roof support. They should not be placed directly above your roof's overhang or above doorways because these areas may not be able to support the weight of a load of snow.
Snow breaks are also intended to be used on buildings that have problems with ice damming. Overhangs are unheated and ice tends to accumulate on them.
Holding snow on the overhang will only increase problems with ice damming rather than prevent them.
Types of Mounts
Snow breaks may be either seam mounted or surface mounted. Seam-mounted snow breaks are installed using hex screws and are usually installed onto metal roofs.
Surface-mounted snow breaks can be fastened with adhesive alone or along with self-tapping screws that are drilled into pre-dimpled holes in the guard.
Shape and Height
The height and shape of the snow break affects how much snow and ice it is able to hold back. The snow break should be placed at the lowest portion of roofing panel at the area of your roof where the snow and ice moves.
The snow break should be at least the height of the roof's seam so that it can hold the ice in place until it melts.