Damper- A metal "door" placed within the fireplace chimney. Normally closed when the fireplace is not in use.

Dampproofing- The black, tar like waterproofing material applied to the exterior of a foundation wall.

Daylight- The end of a pipe (the terminal end) that is not attached to anything.

Dead bolt- An exterior security lock installed on exterior entry doors that can be activated only with a key or thumb-turn. Unlike a latch, which has a beveled tongue, dead bolts have square ends.

Dead light- The fixed, non-operable window section of a window unit.

Deck, decked- To install the plywood or wafer board sheeting on the floor joists, rafters, or trusses.

Dedicated circuit- An electrical circuit that serves only one appliance (ie, dishwasher) or a series of electric heaters or smoke detectors.

Default- Breach of a mortgage contract (not making the required payments).

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

Delamination- Separation of the plies in a panel due to failure of the adhesive.  Usually caused by excessive moisture.

Disconnect- A large (generally 20 Amp) electrical ON-OFF switch.

Discount rate- A mortgage interest rate that is lower than the current rate for a certain period of time, e.g. 2.00% below variable rate for 2 years.

Doorjamb, interior- The surrounding case into which and out of which a door closes and opens. It consists of two upright pieces, called side jambs, and a horizontal head jamb. These 3 jambs have the "door stop" installed on them.

Door operator- An automatic garage door opener.

Door stop- The wooden style that the door slab will rest upon when it's in a closed position.

Dormer- An opening in a sloping roof, the framing of which projects out to form a vertical wall suitable for windows or other openings.

Double glass- Window or door in which two panes of glass are used with a sealed air space between.  Also known as Insulating Glass.

Double hung window- A window with two vertically sliding sashes, both of which can move up and down.

Down payment- The difference between the sales price and the mortgage amount. A downpayment is usually paid at closing.

Downspout- A pipe, usually of metal, for carrying rainwater down from the roof's horizontal gutters.

Drain tile- A perforated, corrugated plastic pipe laid at the bottom of the foundation wall and used to drain excess water away from the foundation. It prevents ground water from seeping through the foundation wall. Sometimes called perimeter drain.

Draw- The amount of progress billings on a contract that is currently available to a contractor under a contract with a fixed payment schedule.

Drip- (a) A member of a cornice or other horizontal exterior finish course that has a projection beyond the other parts for throwing off water.(b) A groove in the underside of a sill or drip cap to cause water to drop off on the outer edge instead of drawing back and running down the face of the building.

Drip cap- A molding or metal flashing placed on the exterior topside of a door or window frame to cause water to drip beyond the outside of the frame.

Dry in- To install the black roofing felt (tar paper) on the roof.

Drywall (or Gypsum Wallboard (GWB), Sheet rock or Plasterboard)- Wall board or gypsum- 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 and is used in bathrooms and other "wet areas".

Ducts- The heating system. Usually round or rectangular metal pipes installed for distributing warm (or cold) air from the furnace to rooms in the home.  Also a tunnel made of galvanized metal or rigid fiberglass, which carries air from the heater or ventilation opening to the rooms in a building.

Due-on-sale- A clause in a mortgage contract requiring the borrower to pay the entire outstanding balance upon sale or transfer of the property.

Dura board, dura rock- A panel made out of concrete and fiberglass usually used as a ceramic tile backing material. Commonly used on bathtub decks. Sometimes called Wonder board

DWV (drain-waste-vent)- The section of a plumbing system that carries water and sewer gases out of a home.