Step flashing, valleys, hips and ridges · Lesson 1 of 4

Step flashing, valleys, hips and ridges: principles and terminology

The shingle-fashion lapping rule, step flashing and the kickout, base flashing at a headwall, open and closed valleys, hip and ridge coverings in shingle and metal, the fall-protection boundary, and which document governs.

You will be able to: Name the pieces that make a roof-to-wall joint, a valley, a hip and a ridge watertight, define their terms, state the one lapping rule that governs them, and state the fall-protection boundary and the order of authority for a job.

10 min · 11 slides · 7 questions

All lessons in this module

Slide 1 of 11

One rule: upper laps over lower

The U.S. Department of Energy describes step flashing as integrated with the roof and wall drainage planes in shingle fashion, with each upper layer lapping over the layer below.

Every piece in this module follows the same rule: step pieces, valley sheets, hip caps and ridge caps each pass water down onto the surface below, never behind it.

Sources

Step Flashing at Roof-Wall Intersections - U.S. Department of Energy, Building Science Education
Step and Kick-Out Flashing at Roof-Wall Intersections (last updated 2020-09-14) - U.S. Department of Energy / Pacific Northwest National Laboratory, Building America Solution Center

Videos for this lesson

What this video shows: The valley types named in its description: closed-cut, California, open and woven, and IKO's recommendation of open metal valleys. A manufacturer's view.

Video: How to Shingle a Valley - Blueprint for Roofing by IKO North America, on YouTube. AFS checked its description against this lesson.

Glossary

Step flashing: A row of separate pieces of flashing where a sloped roof meets a sidewall, one piece set with each shingle course, each lapping over the one below.
Kickout diverter: The first piece of step flashing at the bottom of a roof-to-sidewall run, a seamless one-piece non-corrosive piece that sends water out into the gutter instead of down the wall (PNNL).
Base flashing: The flashing bedded along the face of a dormer or other wall that a roof runs into across the slope; the first step piece turns the corner over it (ProTradeCraft dormer video).
Open valley: A valley whose lining is left exposed, with the roof covering trimmed back on each side; the 2018 IRC calls this a valley lining exposed.
Closed valley: A valley covered with shingles over a lining, as the 2018 IRC describes it; closed-cut and woven valleys are two ways of covering it.
Hip: The sloping outside corner where two roof planes meet; its length is the plan run times a factor that depends on the pitch.
Ridge: The horizontal line at the top where two roof slopes meet, covered by a ridge cap.