Damper
A baffle used to open or close the throat of ventilators.
Dead Load
The weight of the Building System construction consisting of members such as
framing and covering.
Dealer
See “Builder”.
Deck
A flat structural element that is fastened to the roof framing members, typically
corrugated metal sheets or plywood. It acts as the substrate for non-structural roof
panels.
Deflection
The displacement of a structural member relative to its supports due to applied loads.
Deflection should not be confused with "Drift".
Design Loads
The loads expressly specified in the contract documents that the Metal Building
System is designed to safely resist.
Design Professional
The Architect or Engineer responsible for the design of a Construction Project.
Dew Point Temperature
The temperature at which water vapor condenses in cooling air at the existing
atmospheric pressure and vapor content. Cooling air below the dew point will cause
condensation.
Diagonal Bracing
See "Bracing".
Diaphragm Action
The resistance to racking generally offered by the panels, fasteners, and members to
which they are attached.
Direct Tension Indicator
See "Load Indicating Washer".
Door Guide
An angle or channel used to stabilize or keep plumb a sliding or rolling door during its
operation.
Double Lock Standing Seam
A standing seam in which the female component of the seam is wrapped and folded
approximately 360 degrees around the male seam component. (The male component is
interlocked and usually folded 180 degrees). See “Standing Seam”.
Downspout
A vertical conduit used to carry runoff water from a scupper, conductor head or gutter
of a building to a lower roof level, or to the ground or storm water runoff system.
Drift (Sidesway)
Horizontal displacement at the top of a vertical element due to lateral loads. Drift
should not be confused with "Deflection".
Drift (Snow)
The snow accumulation at a height discontinuity.
Drift Pin
A tapered pin used during erection to align holes in steel members to be connected by
bolting.
Drip Edge
A metal flashing, with an outward projecting lower edge, intended to control the
direction of dripping water and to protect underlying building components.