Kickout Flashing (Diverter)

A kickout flashing, also called a diverter or kick-out, is installed where the lower edge of a roof meets a wall that continues down past the eaves, for example where a garage roof ends against the side of a two-storey house. Without it, water flowing down the step flashing reaches the end of the roof and runs straight down the face of the wall, often behind the cladding, causing hidden rot and mould.

How it works

The kickout is effectively the bottom piece of step flashing with an angled lip that projects out from the wall, deflecting water onto the roof edge and into the gutter. US Department of Energy guidance describes it as directing rainwater off the eave and into the gutter, away from the wall.

Code status

The US International Residential Code requires flashing at roof-wall intersections, and section R903.2.1 addresses kickout (diverter) flashing where a roof meets a wall at the eaves. Building departments in jurisdictions that adopt the IRC publish guidance on the detail.

Installation guidance

According to the Building America Solution Center:

• Prefabricated seamless, non-corrosive diverters are preferred over site-bent pieces, which can leak at seams.
• The diverter is installed as the first piece of step flashing, flat on the roof and flush with the sidewall.
• It is fastened to the roof deck and starter course, not to the sidewall.
• The first shingle and next step flashing lap at least 4 in (102 mm) over the diverter.
• The wall's water-resistive barrier is lapped over the top of the diverter so water drains outward.

Retrofitting

Kickouts are frequently missing on older houses, and staining or rot on the wall below the end of a roof is a typical sign. Adding one usually means removing some cladding to integrate it with the wall's drainage plane.