Architectural and Engineering Glossary



Same as auditorium seating.

Theatrical Gauze

A stiff gauze,1,usually of cotton or linen;used on the stage of a theater for curtains or scenery.


A precision instrument used in surveying;consists of an alidade which is equipped with a telescope,a leveling device,and an accurately graduated horizontal circle;also may carry an accurately graduated vertical circle.


A small upper stage or balcony in the stage structure of the ancient theater,on which persons representing divinities sometimes appeared and spoke.


A quantity of heat equivalent to 100,000 Btu.


See bath,3.

Thermal Barrier

See thermal break.

Thermal Bath

See bath,3.

Thermal Break,thermal Barrier

An element of low heat conductivity placed in an assembly to reduce or prevent the flow of heat between highly conductive materials;used in some metal window or curtain wall designs intended for installation in cold climates.

Thermal Bridge

Same as cold bridge. 

Thermal Capacity

See heat capacity. 

Thermal Conductance

The time rate of flow of heat through a unit area of material from one of the faces of the material to the other,for a unit temperature difference between the two faces,under steady state conditions.

Thermal Conduction

The process of heat transfer through a material medium in which kinetic energy is transmitted by particles of the material from particle to particle without gross displacement of the particles.

Thermal Conductivity

The rate of transfer of heat by conduction;the amount of heat per unit of time per unit area that is conducted through a slab of unit thickness of a material if the difference in temperature between opposite faces is one degree of temperature;a property of the material itself,usually represented by the letter k and called k factor.

Thermal Conductor

A material which readily transmits heat by means of thermal conduction. 

Thermal Cutout

An overcurrent protective device in an electric circuit;contains a heater element and a renewable fusible member which opens when the current is so great as to produce sufficient heat to melt it;not designed to interrupt short-circuit currents.

Thermal Diffusivity

The thermal conductivity divided by the product of the specific heat and unit weight;an index of the ease with which a material undergoes a change in temperature.

Thermal Emissivity

The ratio of the rate of radiant heat energy emitted by a body at a given temperature to the rate of radiant heat energy emitted by a blackbody,1 at the same temperature,in the same surroundings.

Thermal Endurance

A measure of the capability of glass to withstand thermal shock.

Thermal Expansion

The change in length or volume which a material or body undergoes on being heated.

Thermal Finish

Same as flamed finish.

Thermal Insulating Cement

A prepared composition,in dry form,comprising granular,flaky,fibrous,or powdery materials;when mixed with a suitable proportion of water,it develops a plastic consistency,and if applied to a surface,dries in place and forms a covering that provides thermal insulation.

Thermal Insulation Board

A preformed rigid or semirigid material in board or block form,which provides resistance to heat flow.

Thermal Insulation,heat Insulation

A material providing high resistance to heat flow;usually made of mineral wool,cork,asbestos,foam glass,foamed plastic,diatomaceous earth,etc.;fabricated in the form of batts,blankets,blocks,boards,granular fill,and loose fill.

Thermal Load

A load on a structure which is induced by changes in temperature.

Thermal Mass

Any material or wall that can absorb heat or cold and release it at a later time.Also see roof pond, rock storage,and Trombe wall.

Thermal Movement

Changes in dimension of concrete or masonry as a result of temperature changes.

Thermal Protector

For a motor or motor compressor,a protective device which protects the motor against dangerous overheating,due either to failure to start or to overload.

Thermal Radiation

The transmission of heat from a hot surface to a cooler one in the form of invisible electromagnetic waves,which,on being absorbed by the cooler surface,raise the temperature of that surface without warming the space between.

Thermal Resistance

The reciprocal of thermal conductance.

Thermal Resistivity

An index of a material’s resistance to the transmission of heat;the reciprocal of thermal conductivity.

Thermal Shock

The sudden stress produced in a body or in a material as a result of a sudden temperature change.

Thermal Storage

The means by which solar energy is collected for re-radiation at a later time.

Thermal Storage Roof

In a passive solar energy system,a roof that provides thermal mass;also see roof pond.

Thermal Storage Wall

In a passive solar energy system,a wall acting as a thermal mass;located between the collectorand the space to be heated;seeTrombe wall.

Thermal Stress Cracking

The crazing of some thermoplastics as a result of overexposure to high temperature.

Thermal Stress,temperature Stress

Stress introduced by uniform  or nonuniform temperature change in a structure or material which is constrained against expansion or contraction.

Thermal Valve

A valve whose action is controlled by a thermally responsive element.

Thermal-fusion Joint

Same as heat fusion joint.


Descriptive of a material such as synthetic resin which hardens when heated or cured,and does not soften when reheated.

Throat Opening

In a steel doorframe,the opening between the backbends of the frame.

Throttling Valve

In a piping system,an orifice designed to control the rate of flow through it. 

Through Arch

Any arch which is set in a thick,heavy wall.

Through Bolt

A bolt which passes completely through the members it connects.

Through Bond

In a masonry wall,the transverse bond formed by stone units or bricks extending through the wall.

Through Check

In a timber,a check which extends from one surface through to the opposite side.

Through Lot

A lot,other than a corner lot,having frontage on two public streets or highways.

Through Shake

In timber,a shake which extends between any two faces.

Timber Framing

See frame.

Timber Joint Connector

Same as timber connector.