Glossary

Deck: The surface, installed over the supporting framing members, to which the roofing is applied.

De-humidistat: A control mechanism used to operate a mechanical ventilation system based upon the relative humidity in the home.

Dimension lumber: Wood lumber that ranges from 2 inches thick up to, but not including, 5 inches thick and 2 or more inches wide. Includes joists, rafters, studs, and planks.

Designer: One who designs houses, interiors, landscaping or other objects. When used it the context of residential construction it usually suggests that a designer is not a licensed architect. Most jurisdictions don't require an architectural license for most single family construction.

Door header: A beam located over a door or window to carry or redirect any load from above the door to the side door studs.

Dormer: Any structure whose framing projects out of a sloping roof to form a vertical wall suitable for windows or other openings.

Double Hung Window: A window with two vertically sliding sashes. This is a very common older window design, was usually made out of wood and tends to require frequent repairs.

Double coverage: Application of asphalt roofing so that the lapped portion is at least 2 inches wider than the exposed portion, resulting in two layers of roofing material over the deck.

Downspout: A pipe for draining water from roof gutters. Also called a leader.

Drip edge: A narrow preformed piece of sheet metal placed along the edge of a roof line so it overhangs the edge of the roof and allows water to be carried beyond the roof edge and drip directly to the ground.

Dry rot: A wood fungus that thrives in damp conditions and turns wood fibers into powder.

Drywall or Gypsum Wallboard (GWB) or Sheet rock or Plasterboard: A wall finish consisting of a manufactured panel made out of gypsum plaster and encased in a thin cardboard. Usually 1/2" thick and 4' x 8' or 4' x 12' in size. The panels are nailed or screwed onto the framing and the joints are taped and covered with a 'joint compound'. 'Green board' type drywall has a greater resistance to moisture than regular (white) plasterboard.