Valley flashing

[RICHARD TAN]

Is valley flashing to be extended out 4" oc, how about the edge or end of flashing?

[Jerry Peck - Codeman]

Hi Richard,

The valley flashing is required to be a minimum of 16 inches wide, centered over the valley, and carried all the way to, but not necessarily over, the drip edge.

However, by carrying the sides of the 16 inch wide valley metal to the edge of the drip edge, an overhanging 'V' shape is created.

This 'V' shape may be left, the 'V' may be cut back along the drip edges then across the center to create a smaller 'v', or it would be trimmed back to the inside corner following the drip edge line.

Most often, though, what roofers do to leave a smaller 'v' is to stop the valley metal short, sometimes at the inside roof edge of the drip edge roof face, which means the valley metal is not installed properly and fully to the drip edge, and sometimes they even stop the valley metal back further to reduce the 'v' even more.

One thing I always did was use my tape measure and measure across the wide straight edge of the bottom of the 'V', that should measure 16 inches minimum.

If it measure less, look along the top of the drip edge and see if the valley metal was trimmed back even with the drip edge (you will rarely find this done, which is an acceptable method of reducing the size of the 'v') or if you see the end of the valley metal extend up under the roof covering short of the edge (which is what you will likely find 90% of the time and which is wrong).

Codeman