Base flashing, counterflashing and reglets · Lesson 4 of 4

Base flashing, counterflashing and reglets: defects, verification and case study

The defects that recur at roof-to-wall terminations, what correct looks like, the chimney side that fails most often, field inspection and records, owner maintenance, and a reroof case study where added insulation leaves the existing reglet too low.

You will be able to: Recognise the recurring roof-to-wall termination defects and their causes, verify an installation against its governing documents with measured values, and diagnose a reroof where the existing reglet no longer fits, documenting the evidence and the corrective options.

9 min · 10 slides · 6 questions

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Slide 1 of 10

The recurring defects

Levine lists insufficient overlap, exposed fasteners, shallow reglets and missing hook dams among the defects to avoid.

He adds ledges that drain water into the wall and inappropriate materials.

Each has a cause the installer controls: layout, cutting, fastening, lapping or the choice of metal.

Sources

Anatomy of a regleted counterflashing (Jeffrey S. Levine), with NRCA editor's note, Professional Roofing, November 2022 - National Roofing Contractors Association (Professional Roofing)

Glossary

Ledge: Part of a counterflashing's reglet flange or of the masonry that projects from the wall face and catches water; Levine avoids it by making the flange the same depth as the reglet.
Hook dam: Levine: the detail at the back end of the counterflashing's reglet flange that impedes the passage of stray moisture into the wall.
Capillary break: A gap or sharp bend that stops water being drawn up between two surfaces; Hodgin forms one by bending the counterflashing sharply down past the step flashing.
Surface-mounted counterflashing: Counterflashing fixed to the face of a wall rather than into it. Used in sealed manufacturer systems (Fry Reglet type SM; Tremco DWG 59); Hodgin finds it the most common chimney defect on brick.