Architectural and Engineering Glossary

Natural Environment

The aggregate of the natural external surroundings and conditions, in contrast to the built environment (i.e., those surroundings and conditions resulting from construction by human beings).

Natural Fiber

Any fiber made from a mineral, plant, or animal source, as opposed to a synthetic fiber.

Natural Finish

Any finish resulting from the application of a transparent substance (such as a varnish, water repellent preservative, sealer, or oil) which does not affect significantly the original color or grain.

Natural Finish Tile

Ceramic facing tile having unglazed or uncoated surfaces which have been fired to the natural color of the material used in forming the body of the tile.

Natural Foundation

A foundation which requires no special preparation of the soil below to support the structure.

Natural Frequency

One of a number of frequencies at which a system or object tends to vibrate if subject to a mechanical displacement or impact and then allowed to vibrate freely.

Natural Gas

A combustible hydrocarbon gas having a calorific value of about 1000 Btu per cubic foot (8,900 kilocalories per cubic meter) of gas;the most commonly available gas from utility companies.

Natural Grade

The elevation of the original or undisturbed natural surface of the ground.

Natural Light

Daytime light from the sun and sky,as opposed to light from artificial sources.

Natural Pigment

See earth pigment.

Natural Pozzolan

A raw or calcined natural material (such as volcanic ash) which has pozzolanic properties.

Natural Resin

A solid,thermoplastic organic substance which occurs in nature;is flammable and a nonconductor of electricity.

Natural Sand

Sand which is the result of natural disintegration and abrasion of rock.

Natural Stone

True stone,as distinguished from imitations.The term is a  redundancy, as stone is,by definition,natural in its occurrence. 

Natural Ventilation

Ventilation by air movement caused by natural forces,rather than by fans.


Describing stone that has been split (cleaved) parallel to its stratification, yielding an irregular but nearly flat surface.

Natural-draft Boiler

A boiler system in which a chimney is required to draw the products of combustion through the boiler or furnace.

Natural-draft Chimney

A chimney that draws the gases and smoke of combustion from a furnace because of the natural draft it develops; operates without auxiliary mechanical draft equipment.

Natural-seasoned Lumber

See air dried lumber.

Naval Stores

1.Oils,resins,tars,and pitches obtained from the oleoresin of pine trees.2. Obsolete name for resin and turpentine.


1.The middle aisle of a church. 2.By extension, both middle and side aisles of a church from the entrance to the crossing or chancel.3.That part of the church intended primarily for the laity.

Nave Arcade

The open arcade between the central and side aisles.


Abbr. for “National Building Code.”


Abbr. for “National Board of Fire Underwriters.”


1.Abbr. for “National Bureau of Standards.”2.Abbr. for “natural black slate.”3.Abbr. for “New British Standard.”


Abbr. for “noise criterion.”

NC Curves

A series of curves of octave band sound spectra, used to provide a single number rating of the noisiness of an indoor space. A measured octave band spectrum is compared with this set of curves to determine the NC level of the space in which the measurements were made.


On drawings,abbr. for “noncorrosive metal.”


(US) Abbr. for the “National Concrete Masonry Association.”


Abbr. for the “National Conference of States on Building Codes and Standards.”


Descriptive of plaster or cement mixed without the addition of any material except  water.See neat cement.

Neat Cement

1.Hydraulic cement in the unhydrated state. 2.Cement mortar made without the addition of sand.

Neat Cement Grout

1.A fluid mixture of hydraulic cement and water,with or without admixture.2.The hardened equivalent of such mixture.

Neat Cement Paste

A mixture of hydraulic cement and water,both before and after setting and hardening.

Neat Line, Net Line

1.A line which defines the limits of work, such as an excavation, cut stone,etc.2.The true face line of a building regardless of the projections of the stones;a line back of,or inside of,incidental projections.

Neat Plaster

Plaster made without aggregate. 

Neat Size

The exact size after preparation. 

Neat Work

Brickwork set at the base of a wall above the footings.

Nebulé Molding, Nebuly Molding

A characteristic Norman molding with an undulating lower edge.


Abbr. for National Electrical Code.


A privy in an ancient castle or a monastery.


1.In the classical orders, the space between the bottom of the capital and the top of the shaft, which is marked by a sinkage or a ring of moldings.2.A section of the branch duct that connects an air diffuser with the main supply duct.

Neck Molding

A necking which takes the form of a molding of any type;same as necking, 


1.Same as neck.2.A molding  or group of moldings between a column and capital.3.Any ornamental band at the lower part of a capital;a hypotrachelium.4.An irrecoverable reduction in cross section of a sealant under stress.


1.A city of the dead;a large cemetery in ancient Egypt,Greece,Phoenicia,Carthage,etc.2.An ancient or historic burial place.


1.A piece of timber laid  horizontally and supported on props or shores under a wall or building,etc.;provides temporary support while the foundation or part beneath is altered,repaired,or underpinned.2.A short timber, or the like, which passes through a hole in a wall;used to support a shore,a scaffold, etc.

Needle Bath

A shower bath containing pipes with a large number of tiny holes through which a spray of water strikes the bather in tiny jets.

Needle Beam

A crossbeam supporting a load;used in underpinning foundation walls; attached to columns at its ends,clear of the existing footing. 

Needle Beam Scaffold

Same as needle scaf fold.

Needle Pile

A very slender steel pile used in underpinning operations.