- Damp Proof Course
- A non-permeable membrane placed above ground level in a brick or stonewall to prevent moisture seeping up into the structure.
- Damp Proofing
- Actions taken to stop the passage of moisture through a wall or floor. Material i.e.; plastic sheeting used to stop moisture penetration.
- Decking
- Wood covering the roof, under the shingles. Usually OSB board.
- Deferred Maintenance
- Maintenance that has not been carried out when it was needed.
- Deflection
- Bending or sagging that occurs when structures are subjected to heavy weights, furnishings, people, Etc. Some sagging is acceptable.
- Deterioration
- Damage occurring over a period of time, due to a lack of maintenance.
- Door Jam
- The frame that holds a door. The wood on both sides are called the jambs, an across the top the head jam.
- Dormer
- Framed window unit projecting through the sloping side of the roof.
- Double Coverage
- Application of asphalt roofing such that the lapped portion is at least two inches wider than the exposed portion, resulting in two layers of roofing material over the deck.
- Double Hung Window
- Window with two moving sashes one above the other.
- Double-glazing
- Two panes of glass with an air space between them in a sealed unit. Increases the insulation factor. May be gas filled to further increase the insulation.
- Doubled Up Conductors
- The wiring of two or more circuits to a fuse/breaker.
- Downspout
- Pipe between the gutter and the drain.
- Drip Edge
- A non-corrosive, non-staining metal used along the eaves and rakes to allow water run-off to drip clear of underlying construction.
- Dry Rot
- A fungus that destroys wood, needs moisture and warmth in a dark environment.
- Drywall
- Usually refers to gypsum board, a board made of plaster sandwiched between two sheets of paper.
- Ducts
- The large pipes or tubes used to move air between the heating or cooling equipment and the vents.