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Term Definition
Relative Humidity

The ratio of the amount of water vapor present in the air to that which the air would hold if saturated at the same temperature.

Remote Control Circuit

An electric circuit that controls any other circuit using a relay or other such device.

Resiliance

The property of a material whereby it gives up its stored energy when deforming force is removed.

Resiliency

The ability to regain the initial shape after being deformed.

Resilient Flooring

Finished flooring made from a resilient material, such as polyvinyl chloride or rubber.

Resin

A natural or synthetic material that is the main ingredient of paint and binds the ingredients together.

Resistance, Electric

The physical property of a conductor or electric-consuming device to resist the flow of electricity, reducing power and generating heat.

Retaining Wall

A wall that bears against soil or other material and resists lateral and other forces from the material being held in place.

Retarder

An admixture used to slow the setting of concrete.

Return Air

Air removed from a space and vented or reconditioned by a furnace, air conditioner, or other apparatus.

Reverberation

Persistence of sound after the source stops. When one hears the 10th, 20th, 50th, 100th, etc., reflection of a sound, one hears reverberation.

Reverberation Time

Essentially the number of seconds it takes a loud sound to decay to inaudibility after the source stops. Strictly, the time required for a sound to decay 60 dB in level.

Ridge

Peak of a roof where the roof surfaces meet at an angle. Also may refer to the framing member that runs along the ridge and supports the rafters.

Rigid Frame

A structural framework in which the beams and columns are rigidly connected (no hinged joints).

Rise

Measurement in height of an object; the amount it rises. The converse is "fall."

Riser

Vertical face of a step supporting the tread in a staircase.

Riser, Plumbing

A water supply running vertically through the building to supply water to the various branches and fixtures on each floor.

Rivet

A metal fastener used to hold metal plates by passing through holes in each and having a head formed on the protruding end.

Rock Anchor

A post-tensioned cable or steel rod inserted into a hole drilled in rock and grouted in place.

Romex

A nonmetallic-sheathed electric cable of type NM or NMC.

Roof Drain

A drain on the roof to carry away water to a downspout.

Roof Planks

Precast gypsum concrete members used for decking roofs.

Room Cavity Ratio

A relationship between the height of a room, its perimeter, and the height of the work surface above the floor divided by the floor area.

Rough Framing

Structural elements of a building or the process of assembling elements to form a supporting structure where finish appearance is not critical.

Rows

Related to carpets, the number of tufts per inch.

Sabin

Measure of sound absorption of a surface, equivalent to 1 sq. ft. of a perfectly absorptive surface.

Saddle

A ridge in a roof deck that divides two sloping parts, diverting water toward roof drains.

Safing

Fire stop material in the space between floor slab and curtain wall in multi-story construction.

Safing Off

Installation of fire safety insulation around floor perimeters, between floor slab and spandrel panels. Insulation helps retain integrity of fire resistance ratings.

Sandstone

A sedimentary rock formed from sand.

Sanitary Sewage

Waste material containing human excrement and other liquid wastes.

Sanitary Sewer

A sewer that receives sanitary sewage without the infusion of other water such as rain, surface water, or other clear water drainage.

Sapwood

The wood near the outside of the log just under the bark.

SBCCI

Southern Building Code Congress International, nonprofit organization that publishes the Standard Building Code.

Scab

Small piece or block of wood that bridges several members or provides a connection or fastening between them.

Scratch Coat

The first coat of gypsum plaster that is applied to the lath.

Screed

A tool used to strike off the surface of freshly poured concrete so it is flush with the top of the form.

Screeding

The process of striking off the surface of freshly poured concrete with a screed so it is flush with the top of the form.

Scupper

An outlet in a parapet wall for the drainage of overflow water from the roof to the outside of a building.

Scuttle

An opening through the ceiling and roof to provide access to the roof. It is covered with a waterproof cover. Also referred to as a roof hatch.

Sealant

A mastic used to seal joints and seams.

Sealer

A material used to seal the surface of a material against moisture.

Seasoning

Removing moisture from green wood.

Seated Connections

Connections that join structural steel members with metal connectors, such as an angle upon which one member, such as a beam, rests.

Section Modulus (S)

Numerical relationship, expressed in in.3, of the resistance to stress of a member. It is equal to the moment of inertia divided by the perpendicular distance from the neutral axis to the extremity of the member.

Security Glass

Glass panels assembled with multiple layers of glass and plastic to produce a panel that will resist impact.

Sedimentary Rock

Rock formed from the deposit of sedimentary materials on the bottom of a body of water or on the surface of the earth.

Segregation

The tendency of large aggregate to separate from the sand-cement mortar in the concrete mix.

Seismic Area

A geographic area where earthquake activity may occur.

Seismic Load

Forces produced on a structural mass by the movements caused by an earthquake.

Semitransparent

Coatings that allow some of the texture and color of the substrate to show through.

Sensible Heat

Heat that causes a detectable change in temperature.

Septic Tank

A watertight tank into which sewage is run and where it remains for a period of time to permit hydrolysis and gasification of the contents, which then flow from the tank and are absorbed in the soil.

Service Entrance

The point at which power is supplied to a building and where electrical service equipment, such as the service switch, meter overcurrent devices, and raceways, are located.

Service Equipment

The equipment needed to control and cut off the power supply to a building, such as switches and circuit breakers.

Service Temperature

The maximum temperature at which a plastic can be used without altering its properties.

Shadowing

An undesirable condition where the joint finish shows through the surface decoration.

Shaft Wall

Fire-resistant wall that isolates the elevator, stairwell and vertical mechanical chase in high-rise construction. This wall must withstand the fluctuating (positive and negative) air-pressure loads created by elevators or air distribution systems.

Shales

Clays that have been subjected to high pressures, causing them to become relatively hard.

shared-party-wall

A wall built on the dividing line between two adjoining parcels, in which each owner has an equal share of ownership.

Shear

Force that tends to slide or rupture one part of a body from another part of the body or from attached objects.

Shear Panel

A floor, wall, or roof designed to serve as a deep beam to assist in stabilizing a building against deformation by lateral forces.

Shear Plate Connector

A circular metal connector recessed into a wood member that is to be bolted to a steel member.

Shear Stress

The result of forces acting parallel to an area but in opposite directions, causing one portion of the material to "slide" past another.

Shear Studs

Metal studs welded to a steel frame that protrude up in the cast-in-place concrete deck.

Sheathing

Plywood, gypsum, wood fiber, expanded plastic or composition boards encasing walls, ceilings, floors and roofs of framed buildings. May be structural or non-structural, thermal-insulating or non-insulating, fire-resistant or combustible.

Sheave

A pully over which the elevator wire hoisting rope runs.

Sheeting

Wood, metal, or concrete members used to hold up the face of an excavation.

SHEETROCK

Leading brand of gypsum panel for interior wall and ceiling surfaces, developed and improved by United States Gypsum Company. There is only one SHEETROCK brand Gypsum Panel.

Shop Drawings

Related to steel construction, working drawings giving the information needed to fabricate structural steel members.

Shoring

Temporary member placed to support part of a building during construction, repair or alteration; also may support the walls of an excavation.

Shoring

Bracing used to temporarily hold a wall in position.

Shrinkage Limit

Related to soils, the water content at which the soil volume is at its minimum.

Siamese Connection

A connection outside a building to which firefighters connect an alternate water supply to boost the water used by the fire suppression system.

Sill

Horizontal member at the bottom of a door or window frames to provide support and closure.

Sill Plate

Horizontal member laid directly on a foundation on which the framework of a building is erected.

Silt

Fine sand with particles smaller than 0.002 inches (0.05 mm) and larger than 0.00008 inches (0.002 mm).

Single-Ply Roofing

A roofing membrane composed of a sheet of water-proof material secured to the roof deck.

Sintering

A process that fuses iron-ore dust with coke and fluxes into a clinker.

Site Investigation

An investigation and testing of the surface and subsoil of the site to record information needed to design the foundation and the structure.

Site Plan

A drawing of a construction site, showing the location of the building, contours of the land, and other features.

Site-Cast Concrete

Concrete poured and cured in its final position.

Skylight

A roof opening that is covered with a watertight transparent cover.

Slab

Flat (although sometimes ribbed on the underside) reinforced concrete element of a building that provides the base for the floor or roofing materials.

Slab-On-Grade

A concrete slab poured and hardened directly on the surface of the earth.

Slag

A molten mass composed of fluxes and impurities removed from iron ore in the furnace.

Slake

The process of adding water to quicklime, hydrating it and forming lime putty.

Slip Form

A form designed to move upward as concrete is poured in it.

Slump

A measure of the consistency of freshly mixed concrete, mortar, or stucco.

Slump Test

A test to ascertain the slum of concrete samples.

Slurry

A liquid mixture of water, bentonite clay, or Portland cement.

Slurry Wall

A wall built of a slurry used to hold up the sides of an area to be excavated.

Smelting

A process in which iron ore is heated, separating the iron from the impurities.

Smoke Barriers

Continuous membranes used to resist the passage of smoke.

Smoke Developed Rating

A relative numerical classification of the fumes developed by a burning material.

Soffit

Undersurface of a projection or opening; bottom of a cornice between the fascia board and the outside of the building; underside of a stair, floor or lintel.

Soft-Mud Process

A process used to make bricks when the clay contains moisture in excess of 15 percent.

Softwood

A botanical group of trees that have needles and are evergreen.

Soil Anchors

Metal shafts grouted into holes drilled into the sides of an excavation to stabilize it.

Soil Stack

A vertical plumbing pipe into which waste flows through waste pipes from each fixture.