Roof, wall and foundation transitions · Lesson 1 of 4

Roof, wall and foundation transitions: principles and terminology

Why transitions are where enclosures fail, the control layers that must carry through, the roof-to-wall, eave-to-sidewall and wall-base conditions, the vocabulary, the three datums, who is responsible for each piece, and the safety boundary.

You will be able to: Name the three transitions where a roof, a wall and a foundation meet, say which control layers and which metal pieces cross each one, define the terms a detail uses, and state the datum each dimension is measured from.

9 min · 10 slides · 6 questions

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Slide 1 of 10

Where two assemblies meet

ABAA says roof-to-wall transitions remain one of the most vulnerable points in the building enclosure.

A transition is a joint where one assembly hands its layers to another: roof to wall, sloped roof to sidewall, wall to foundation. Each is built by different trades, so no one trade owns the joint unless the drawings assign it.

Sources

Roof-to-Wall Details (guide detail index) - Air Barrier Association of America

Videos for this lesson

What this video shows: The International Masonry Institute's short clip on where masonry flashings go and why, including the base of the wall, low roof-to-high wall terminations and the tops of walls under parapet caps.

Video: A.07 Masonry flashing - Where and why? by International Masonry Institute, on YouTube. Chosen from the video's published description.

Glossary

Transition: A joint where one building assembly hands its water, air, vapor and thermal control layers to another, such as roof to wall or wall to foundation (a working definition drawn from the ABAA and BSC sources).
Counterflashing: Flashing that protects the top edge of the roof flashing where it extends up a wall, per the Brick Industry Association; it laps down over the roof flashing from the wall above.
Receiver: The part set in the wall that holds the top edge of a counterflashing; Hutchinson says the base flashing should be detailed up to the bottom of it.
Kick-out flashing: Flashing at the eave end of a roof-to-sidewall step flashing that diverts rainwater runoff into the gutter and keeps it off the wall (U.S. Department of Energy).
Base-of-wall flashing: Continuous flashing at the base of a wall, placed above grade, that diverts moisture that has entered the wall out to the exterior (Brick Industry Association).
Datum: The surface a dimension is measured from. UFGS 07 60 00 measures reglet height from the roof deck, IKO measures flashing height from the roof surface, and base-of-wall heights are measured from finished ground.