Glossary - D

» Drywalls - is a building material made of a sheet of plaster covered with heavy paper on both sides; it is also called plasterboard.

» Dry wall partition system - is a good combination of traditional and new building method and it is the fastest way to refurbish existing walls.

» Drytech Insulation Clips - enables easy and proper installation of insulation in Drywalls and prevents insulation to fall down or sagging of insulation in the partition walls.

» Damper A fl ap to control or obstruct the fl ow of gases; specifi cally, a metal control flap in the throat of a fi replace or in an air duct.

» Dampproofi ng A coating intended to resist the passage of water, commonly applied to the outside face of basement walls or to the inner face of a cavity in a masonry cavity
   wall.

» Dap A notch at the end of a piece of material.

» Darby A stiff straightedge of wood or metal used to level the surface of wet plaster or concrete.

» Daylighting Illuminating the interior of a building by natural means.

» Dead load Permanent loads on a building, including the weight of the building itself and any permanently attached equipment.

» Deadman A large and/or heavy object buried in the ground as an anchor.

» Decking A material used to span across beams or joists to create a fl oor or roof surface.

» Deep foundation A building foundation that extends through upper strata of incompetent soil to reach deeper strata with greater bearing capacity.

» Deformation A change in the shape of a structure or structural element caused by a load or force acting on the structure.

» Deformed reinforcing bar Steel reinforcing bars with surface ribs for better bonding to concrete.

» Depressed strand A pretensioning tendon that is pulled to the bottom of the beam at the center of the span to follow more closely the path of tensile forces in the member.

» Derrick Any of a number of devices for hoisting building materials on the end of a rope or cable.

» Design/bid/build project delivery A method of providing design and construction services in which the design and construction phases of the project are provided by different
   entities, usually used in combination with sequential construction.

» Design/build project delivery A method of providing design and construction services in which the design and construction phases of the project are provided by a single
  entity, frequently used in combination with fast track construction. Dew point The temperature at which water will begin to condense from a mass of air with a given moisture
   content.

» Dewatering The extraction of water from an excavation or its surrounding soil.

» Diagonal bracing See Bracing.

» Diamond saw A tool with a moving chain, belt, wire, straight blade, or circular blade whose cutting action is carried out by diamonds.

» Diaphragm action A bracing action that derives from the stiffness of a thin plane of material when it is loaded in a direction parallel to the plane. Diaphragms in buildings are
   typically floor, wall, or roof surfaces of plywood, reinforced masonry, steel decking, or reinforced concrete.

» Die An industrial tool for giving identical form to repeatedly produced or continuously generated units, such as a shaped orifi ce for giving form to a column of clay, a steel wire,
   or an aluminum extrusion; a shaped punch for making cutouts of sheet metal or paper; or a mold for casting plastic or metal.

» Die-cut Manufactured by punching from a sheet material.

» Differential settlement Subsidence of the various foundation elements of a building at differing rates.

» Diffuser A louver shaped so as to distribute air about a room.

» Dimension lumber Lengths of wood, rectangular in cross section, sawed directly from the log.

» Dimension stone Building stone cut to a rectangular shape.

» Direct tension indicator washer See Load indicator washer.

» Distribution rib A transverse beam at the midspan of a one-way concrete joist structure, used to allow the joists to share concentrated loads.

» Divider strip A strip of metal or plastic embedded in terrazzo to form control joints and decorative patterns. » Dome An arch rotated about its vertical axis to produce a structure
  shaped like an inverted bowl; a form used to make one of the cavities in a concrete waffle slab.

» Dormer A structure protruding through the plane of a sloping roof, usually containing a window and having its own smaller roof.

» Double glazing Two parallel sheets of glass with an airspace between.

» Double-hung window A window with two overlapping sashes that slide vertically in tracks.

» Double shear Acting to resist shear forces at two locations, such as a bolt that passes through a steel supporting angle, a beam web, and another supporting angle.

» Double-skin facade An exterior wall system consisting of two separate glass skins separated by an interstitial space; also called dual-wall facade or double-skin wall.

» Double-skin wall See Double-skin facade.

» Double-strength glass Glass that is approximately 1/8 inch (3 mm) thick.

» Double tee A precast concrete slab element that resembles the letters TT in cross section.

» Dovetail slot anchor A system for fastening to a concrete structure that uses metal tabs inserted into a slot that is small at the face of the concrete and larger behind.

» Dowel A short cylindrical rod of wood or steel; a steel reinforcing bar that projects from a foundation to tie it to a column or wall, or from one section of a concrete slab or
   wall to another.

» Downspout A vertical pipe for conducting water from a roof to a lower level, also called a leader.

» Drainage Removal of water.

» Drainage backfi ll Crushed stone or gravel backfi ll materials with good drainage characteristics, placed around a foundation to facilitate drainage.

» Draped tendon A posttensioning strand that is placed along a curving profi le that approximates the path of the tensile forces in a beam.

» Drawing Shaping a material by pulling it through an orifi ce, as in the drawing of steel wire or the drawing of a sheet of glass.

» Drawings See Construction Drawings.

» Drawn glass Glass sheet pulled directly from a container of molten glass.

» Drift Lateral defl ection of a building caused by wind or earthquake loads.

   Drift pin A tapered steel rod used to align bolt holes in steel connections during erection.

» Drilled pier See Caisson.

» Drip A discontinuity formed into the underside of a window sill or wall component to force adhering drops of water to fall free of the face of the building rather than to move
   farther toward the interior.

» Dropchute A fl exible hoselike tube for placing concrete; used to break the fall of the concrete and prevent segregation.

» Drop panel A thickening of a two-way concrete structure at the head of a column.

» Drying shrinkage Shrinkage of concrete, mortar, or plaster, that occurs as excess water evaporates from the material.

» Dry-pack grout A low-slump cementitious mixture tamped into the space in a connection between precast concrete members.

» Dry-press process A method of molding slightly damp clays and shales into bricks by forcing them into molds under high pressure.

» Dry-set mortar A tile setting mortar formulated with portland cement, sand, and water retention compounds, used in thinset tile applications.

» "Dry" systems Systems of construction that use little or no water during construction, as differentiated from systems such as masonry, plastering, and ceramic tile work.

» Drywall See Gypsum board.

» Dry well An underground pit fi lled with broken stone or other porous material from which rainwater from a roof drainage system can seep into the surrounding soil.

» Dual-wall facade See Double-skin facade.

» Duct A hollow conduit, commonly of sheet metal, through which air can be circulated; a tube used to establish the position of a posttensioning tendon in a concrete structure.

» DWV Pipe Drain–waste–vent pipe; the part of the plumbing system of a building that removes liquid wastes.