Architectural and Engineering Glossary


Heading Bond

Same as header bond.

Heading Chisel

See mortise chisel.

Heading Course

In masonry,a course consisting entirely of headers;a header course.

Heading Joint

1.A joint between two pieces of timber which are joined in a straight line,end to end.2.A masonry joint formed between two stones in the same course.


In the lapping of roofing shingles,the shortest distance between (a) the lower edge of an overlapping shingle and (b) the upper edge of the lapped unit in the second course below.

Headmold, Dripstone, Head Molding, Hood Mold, Weather Molding

The molding carried around or over the head of a door or window. 

Headroom, Headway

1.The clear vertical space (as from floor to ceiling),esp.the height which is available for passage.2.In the stage- house of a theater,the clear height over the gridiron.


A supporting beam for a church bell. 


The principal stone in a foundation,as the cornerstone of a building or the key stone of an arch.


A masonry or concrete retaining wall at the outlet of a drain.


Same as headroom.


The heads and other ornaments on the keystone of an arch.


The outermost layer of the roof of a building.

Healing Stone

A roofing slate or roofing tile.


1.A framework of metal bars or rods placed over a tomb or coffin of a noble or very important person.2.A canopy,usually of openwork or trellis,set over a bier,or more rarely over a permanent tomb;used especially to support candles,lighted at times of ceremony.


The center portion of a log,usually referring to heartwood or duramen.

Heart And Dart

See leaf and dart.

Heart Bond

In masonry,a bond,6 in a masonry wall,in which two headers meet in the middle of the wall and another header covers the joint between them.

Heart Plank

See centerplank.

Heart Shake

A radial crack originating at the heart of a log;usually results from improper sea soning.

Heart-face Boards

Boards which are sawn so that the face side is free of sapwood.


1.The floor of a fireplace (usually brick, tile,or stone) together with an adjacent area of fireproof material.2.An area permanently floored with fireproof material beneath and surrounding a stove.

Hearth  trimmer

See trimmer.


1.A single large stone forming the floor of a fireplace.2.Materials such as fire brick,fireclay products,concrete,etc.,used to form a hearth.


Masonry forming the interior of a wall, pier,etc.,as distinguished from facework.

Heartwood, Duramen

Wood at the core of an exogenous tree;normally darker and much more durable than sapwood.


The form of energy that is transferred by virtue of a temperature difference between two bodies,the transfer being from the  warmer to the cooler body.

Heat And Smoke Vent

Same as smoke and fire vent.

Heat Balance

1.A procedure for determining the efficiency of a combustion process:all heat losses (expressed as percentages) are added together;then their total is subtracted from 100%;the remaining figure represents the efficiency.2.The establishment of a condition of thermal equilibrium in a space,wherein the heat gains just equal the heat losses.

Heat Capacity,thermal Capacity

The amount of heat necessary to raise the temperature of a given mass by 1 degree;numerically equal to the mass multiplied by the specific heat.

Heat Conductivity

See thermal conductivity.

Heat Detector

An alarm initiating device in a fire detection system that detects abnormally high temperatures or rates of rise in temperature. 

Heat Exchanger

A device designed to transfer heat between two physically separated fluids;generally consists of a cylindrical shell with longitudinal tubes;one fluid flows on the inside,the other on the outside.

Heat Filter

An optical filter placed in a light path to reduce heating effect of a light source;transmits the visible spectrum of the light radiated by the source,but rejects the near-infrared radiation.

Heat Flow

See heat transfer.

Heat Gain

The net increase in heat within a space.

Heat Insulation

See thermal insulation.

Heat Load, Heating Load

The total heat per unit time that must be supplied in order to maintain a specified temperature in any space,building,or group of buildings.

Heat Loss

1.The net decrease in heat within a space.2.See building heat-loss factor.

Heat Of Hydration

Heat evolved by chemical reactions with water,as during the setting and hardening of portland cement.

Heat Of Solution

The heat which is liberated by the solution of a material in a solvent.

Heat Quantity

A measured amount of heat,usually expressed in British thermal units (Btu) or in kilocalories.

Heat Recovery

The extraction of heat from any heat source such as lights,engine exhaust,etc.

Heat Sink

The medium or environment where heat is discharged after it has been removed from a heat source;usually the atmosphere or a body of water.

Heat Source

1.The place or the environment from which heat is obtained.2.The place from which a refrigeration system removes heat.

Heat Storage

The storage of solar energy during the day,when it is often abundant,for use at a later time.

Heat Transfer

The flow of heat from one body at higher temperature to another body at a lower temperature,until the two temperatures are equal. 

Heat Transfer Coefficient

See thermal conductance.

Heat Transfer Fluid

Liquid which absorbs heat energy at a heat source (for example,in a solar collector) and then transports this energy to a heat exchanger or to its point of use.

Heat Transmission

The time rate of heat flow;usually refers to the combined effects of conduction,convection,and radiation.