The Four D’s of Building Enclosures: Deflection, Drainage, Drying, and Durability

05.26.16   Thomas L. Bane, PE | More by this Author

The Four D’s of Building Enclosures: Deflection, Drainage, Drying, and Durability

Welcome to the first of a four-part blog column on “The Four D’s of Building Enclosures: Deflection, Drainage, Drying, and Durability.” When applied correctly, the four “Ds” increase the longevity of buildings, and decrease maintenance costs.

In this edition of “The Four Ds of Building Enclosures,” we’ll focus on Deflection.

In building enclosure terms, “deflection” means directing water away from a building. The concept is simple: to keep water out of a building, keep it away from the building.

The principal of using deflection is evident throughout architecture:

Eaves: Eaves are among the most basic application of the deflection principle. Eaves discharge water that collects on the roof by directing it off an overhang that extends several feet from the face of the building.

Tapered Rafter Tails: Tapering exposed rafters at an angle prevents the end of the rafter from getting wet and rotting. Tapers can also be ornamental, adding architectural detail.

Gutters collect and conduct rainwater away from walls.

Stringcourse: A stringcourse (also called a belt course) encircles the building and creates a projecting ledge. Often installed at every floor, the stringcourse collects water on the wall and directs it out away from the building. A drip at its edge prevents the water from tracking back toward the building.

Recessed Windows: Windows in older buildings tend to be recessed from the face of the building to protect a vulnerable opening in the wall. If the exterior walls can be used to deflect water away from the windows, the windows are less likely to leak.

Shutters: In the United States, operable shutter largely aren’t used; most are purely decorative. In some other parts of the world, however, protective shutters are still very much in use. When it’s going to rain, the shutters are closed to protect the windows from leaks.

Stay tuned for our next edition of “The Four Ds of Building Enclosures,” in which we’ll focus on D #2, “Drainage.” We’ll equip you with some tools to help ensure your next project doesn’t have you watching dollars swirl down the drain.

If you’re have trouble with water in your building, or you are planning to construct a building and want to keep water out, SME can help. For more information, contact Tom Bane.


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