| Term | Definition |
| NAAMM | National Association of Architectural Metal Manufacturers. |
| Nadir | The lowest point. |
| NAHB | National Association of Home Builders. |
| Nail | A stiff metal wire fastening device with a point on one end and head designed for impact on the other end. |
| Nail Apron | A leather or fabric pouch attached to a carpenter's belt to carry nails or other fasteners. |
| Nail Bar | A tool which pries open or pulls out driven nails. |
| Nail Couple | A pair of nails that will resist a rotating force. |
| Nail Fracture | See Hammer Fracture. |
| Nail Gun | A mechanical device for driving nails by compressed air. |
| Nail inspection | An inspection made by a municipal building inspector after the drywall material is hung with nails and screws (and before taping). |
| Nail Popping | Protrusion of the nail from gypsumboard, usually attributed to the shrinkage of or use of improperly cured wood framing. |
| Nail Pull Resistance | The ability of gypsum board to resist nail head penetration as defined in ASTM C 473. |
| Nail Set | A small hand tool, like a punch, used for setting finish nails slightly below the surface of the wood. |
| Nail Spotter | In gypsumboard finishing, a small box-type applicator for covering dimpled nail heads with joint compound; see Ames Taping Tools. |
| Nailable Concrete | Concrete, usually made with suitable lightweight aggregate, with or without the addition of sawdust, into which nails can be driven. |
| Nailable Studs | Light gauge metal studs with slots that will accept nails for attachment of wall finishes. |
| Nailer | 1. A wooden strip attached to a concrete, masonry, or steel deck to allow roofing materials to be mechanically fastened. 2. A wooden strip cast into a concrete member for later fastening of finishes by nailing. |
| Nailing Channel | Fabricated from not lighter than 25 gauge steel so as to form slots to permit attachment of lath by means of ratchet-type annular nails, or other satisfactory attachments. |
| Nailing Pattern | The arrangement, spacings, and dimensions of nails used to attach two or more structural members together. |
| NAIMA | North American Insulation Manufacturers Association. |
| Nameplate Plaque | A flat thin piece of metal used for the inscription of a name. |
| Nano- | A prefix meaning one billionth of a part, 10-9. |
| Nanogram | One billionth of a gram. |
| Nanometer | One billionth of a meter. |
| Nanosecond | One billionth of a second. |
| Nanotechnology | The technology of measuring and manufacturing objects of microscopically small size. |
| NAP | The pile on the surface of a carpet or rug. |
| Napkin Dispenser | A hollow, box-like metal device installed in women's restrooms to dispense sanitary napkins and tampons. |
| Naptha | Any of several volatile, flammable liquids obtained by distilling certain materials containing carbon; used as a solvent or thinner in varnish and as a fuel; petroleum naptha is also known as benzine. |
| Narrow Carpet | Fabric woven 27 in. and 36 in. in width, as distinguished from broadloom. |
| Narthex | A vestibule leading to the nave of a church. |
| National Association of Architectural Metal Manufacturers (NAAMM) | 600 South Federal Street, Chicago, Illinois 60605, (312) 922-6222. |
| National Association of Home Builders (NAHB) | 15th and M Streets, NW, Washington, DC 20005, (202) 822-0229. |
| National Builders Hardware Association (NBHA) | 1815 North Fort Myer Drive, Suite 412, Arlington, Virginia 22209, (703) 527-2060. |
| National Building Granite Quarries Association (NBGQA) | North State Street, Concord, New Hampshire 03301. |
| National Bureau of Standards (NBS) | U.S. Dept. of Commerce, Government Printing Office, Washington, DC 20234. |
| National Center for Earthquake Engineering Research (NCEER) | State University of New York @ Buffalo, Red Jacket Quadrangle, Buffalo, New York 14261, (716) 645-3391. |
| National Concrete Masonry Association (NCMA) | 2302 Horse Pen Road, PO Box 781, Herndon, Virginia 22070, (703) 435-9000. |
| National Conference of States on Building Codes and Standards, Inc (NCSBCS) | 505 Huntmar Park Drive, #210, Herndon, Virginia 22070, (703) 437-0100. |
| National Council of Architectural Registration Boards (NCARB) | 1735 New York Avenue, NW, Washington, DC 20006. |
| National Electrical Code (NEC) | A model electrical code written by the National Fire Protection Association and adopted by various jurisdictions as their electrical code. |
| National Electrical Manufacturer's Association (NEMA) | 2101 L Street, NW Washington, DC 20037, (202) 457-8400, FAX (202) 457-8411. |
| National Elevators Manufacturing Industry, Inc (NEMI) | 600 Third Avenue, New York, NY 10016, (212) 986-1545. |
| National Fan Manufacturers' Association (NFMA) | 5-157 General Motors Building, Detroit, Michigan 48202. |
| National Fire Protection Association (NFPA) | Batterymarch Park, Quincy, Massachusetts 02269, (617) 770-3000. |
| National Flood Insurance Program (NFIP) | PO Box 6468, Rockville, Maryland 20849-6468, (800) 638-6620. |
| National Glass Association (NGA) | 8200 Greensboro Drive, McClean, Virginia 22102, (703) 442-4890. |
| National Institute for Occupational Safety and Health (NIOSH) | Hubert H. Humphrey Building, 200 Independence, SW, Washington, DC 20201, (202) 401-6997. NIOSH was established by the Occupational Safety and Health Act of 1970; primary functions are to conduct research, issue technical information, and test and certify |
| National Institute of Building Sciences (NIBS) | 1201 L Street, NW, #400, Washington, DC 20005, (202) 289-7800. |
| National Institute of Standards & Technology (NIST) | Office of Standards Service, Gaithersburg, Maryland 20899, (301) 975-5900. |
| National Lumber Grades Authority, The (NLGA) | |
| National Oak Flooring Manufacturers' Association (NOFMA) | PO Box 3009, Memphis, Tennessee 38173, (901) 526-5016. |
| National Paint & Coatings Association (NPVLA) | 1500 Rhode Island Avenue, NW, Washington, DC 20005, (202) 462-6272. |
| National Particleboard Association (NPA) | 18928 Premiere Court, Gaithersburg, Maryland 20879, (301) 670-0604. |
| National Ready Mixed Concrete Association NRMCA | 900 Spring Street, Silver Springs, Maryland 20910, (301) 587-1400. |
| National Roofing Contractors Association (NRCA) | 10255 West Higgins Road, #600, Rosemont, Illinois 60018-5607, (708) 299-9070. |
| National Sanitation Foundation (NSF) | School of Public Health, University of Michigan, NSF Building 3475 Plymouth Road, Ann Arbor, Michigan 48105, (313) 769-8010. |
| National Spa & Pool Institute (NSPI) | 2111 Eisenhower Avenue, Alexandria, Virginia 22314-4698, (703) 838-0083. |
| National Technical Information Service (NTIS) | Springfield, VA. |
| National Terrazzo and Mosaic Association (NTMA) | 2-A West Loudoun Street, Leesburg, Virginia 22075, (703) 777-7683. |
| National Wood Window & Door Association (NWWDA) | 1400 East Touhy Avenue, #G-54, Des Plains, Illinois 60018, (708) 299-5200. |
| National Woodwork Manufacturers' Association (NWMA) | 205 West Touhy Avenue, Park Ridge, Illinois 60068, (312) 823-6747. |
| Natural Asphalt | Asphalt occurring in nature which has been derived from petroleum by natural processes of evaporation of volatile fractions leaving the asphalt fractions; the native asphalt of most importance are found in the Trinidad and Bermudez Lake deposits; asphalt |
| Natural Clay Tile | A tile made by either the dust-pressed method or the plastic method, from clays that produce a dense body having a distinctive, slightly textured appearance. |
| Natural Cleft | A natural V-shaped channel, space, opening, or fissure in a material. |
| Natural Cleft Slate | Slate which has been split into thinner pieces along its natural cleft or seam; it is rougher in appearance than machined slate. |
| Natural Convection | Fluid motion of air caused by the temperature difference between the solid surface and the fluid with which it is in contact. |
| Natural Draft | A natural stream of air up a chimney, caused by the stack effect, which draws combustion air through the burner or fuel bed. |
| Natural Finish | A transparent finish, usually a drying oil, sealer or varnish, applied to wood for protection against soiling or weathering; such a finish should not seriously change the original color of the wood or obscure its grain pattern. |
| Natural Frequency | The constant frequency of a vibrating system in the state of natural oscillation. |
| Natural Gas Meter | A mechanical measuring and recording device of the volume of natural gas passing a given point. |
| Natural Gray Yarn | Unbleached and undyed yarn spun from a blend of black, brown or gray wools. |
| Natural Resins | Essentially the result of exudation of trees; divided into two large classes, dammars and copals; resins are usually named after the locality in which they are found or the port of shipment. |
| Natural Stone | Any type of stone which is quarried and not manufactured. |
| Naval Stores | A term applied to the oils, resins, tars, and pitches derived from oleoresin contained in, exuded by, or extracted from trees, chiefly species of pines; historically, these were important items in the stores of wood sailing vessels. |
| Nave | The main part of the interior of a church. |
| Navigable streams | Waterways of sufficient depth and width to handle a specified traffic load. |
| NBGQA | National Building Granite Quarries Association. |
| NBHA | National Builders Hardware Association. |
| NBP | A membrane typically reinforced with polyester; resists tears, punctures and weathering; remains flexible at low temperatures and has a low vapor permeability. |
| NBS | National Bureau of Standards. |
| NCARB | National Council of Architectural Registration Boards. |
| NCEER | National Center for Earthquake Engineering Research. |
| NCMA | National Concrete Masonry Association. |
| NCSBCS | National Conference of States on Building Codes and Standards, Inc. |
| Neap tide | A tide having about 10 or 30 percent less range than the average, occuring about the time of quarter moons. |
| Neat | 1. With no dilution and nothing added. 2. Plaster material requiring the addition of aggregate. |
| Neat Cement | Hydraulic cement in the unhydrated state. |
| Neat Cement Grout | A fluid mixture of hydraulic cement and water, with or without admixture; also the hardened equivalent of such mixture. |
| Neat Cement Mortar | Portland cement and water only, no aggregate. |
| Neat Cement Paste | A mixture of hydraulic cement and water, both before and after setting and hardening. |
| NEC (National Electrical Code) | A set of rules governing safe wiring methods. Local codes—which are backed by law—may differ from the NEC in some ways. |
| Needle Beam | A steel or wood beam threaded through a hole in a bearing wall and used to support the wall and its superimposed loads during underpinning of its foundation. |
| Needle Valve | Similar to a globe valve, it has a needle which seats into a small opening to control the flow of liquid. |
| Needlepoint Valve | Type of valve having a needle point plug and a small seat orifice for low flow metering. |
| Negative Float | The condition in a CPM schedule when there is not enough time available to perform some operation. |
| Negative Moment | A result of bending moment in a beam in which the upper part is in tension and the lower part is in compression; compare with Positive Moment. |
| Negative Pressure | 1. Condition that exists when less air is supplied to a space than is exhausted from the space, so the air pressure within that space is less than that in surrounding areas. 2. A pressure within a pipe that is less than atmospheric pressure; also called a |
| Neglect | 1. To pay insufficient attention to. 2. To disregard a duty, leaving it undone. |
| Negligence | The failure to exercise due care |
| Negotiable Instrument | A written promise or request for the payment of a certain sum of money to order or bearer; includes checks, bills of exchange, letters of credit, promissory notes, trade acceptances, and certain bonds. |
| Negotiated Contract | A construction contract where the price has been arrived at by negotiation between owner and contractor rather than by competitive bidding. |
| Neighborhood | In community planning, a residential area in which residents are within walking distance of each other. |
| Neighborhood Shopping Center | A small shopping center; a convenience center. |
| NELMA | The Northeastern Lumber Manufacturers Association. |
| Nelson Stud | A bolt-like rod, sometimes threaded to receive a nut, welded to a steel member for attaching another member. |
| NEMA | National Electrical Manufacturer's Association. |
| NEMA Switch | A electrical switch approved by the National Electrical Manufacturer's Association. |
| NEMI | National Elevators Manufacturing Industry, Inc. |
| Neon | An inert gaseous element occurring in traces in the atmosphere and giving an orange glow when electricity is passed through it in a sealed low-pressure tube; used in advertising and commercial signs. |
| Neoprene | A synthetic rubber (polychloroprene) that is used in fluid or sheet applied elastomeric roofing membranes or flashing; sometimes called chloroprene rubber; sheets are available with or without reinforcing fabric; resists weather, heat, oils, solvents and |
| Neoprene Joint | A fitting of synthetic rubber, neoprene, where two or more members meet. |
| Neoprene Membrane | An impervious, oil-resistant synthetic rubber, manufactured to be installed in layer form; used for roofing and waterproofing. |
| Neoprene Roof | A roof system covered with a sheet of synthetic rubber. |
| Nepheline Syenite | A mineral aggregate consisting chiefly of albite, microcline, and nephelite, each in significant amount. |
| NESHAP | National Emission Standard for Hazardous Air Pollutants - EPA Rules under the Clean Air Act. |
| net | A very light, open-mesh, almost transparent fabric made from cotton, silk, or man-made fibers, usually in white or cream but these days available in a wide range of colors including dramatic dark ones. |
| Net Cross Sectional Area | Of concrete masonry units, the gross cross-sectional area of a section minus the area of cores or cellular spaces; the cross- sectional area of grooves in scored units is not deducted from the gross cross-sectional area to obtain the net cross-sectional a |
| Net Effective Temperature (ET) | This is not an actual temperature in the sense that it can be measured by a thermometer; it is an experimentally determined index of the various combinations of dry-bulb temperature, humidity, radiant conditions, and air movement that induce the same ther |
| Net Income | The remainder of revenues after direct and indirect costs are deducted; profit. |
| Net Lease | A lease in which the tenant pays certain specified costs, such as taxes, insurance, and maintenance, of operating the property; a net, net lease and a net, net, net lease are variations where the tenant pays more of the costs. |
| Net Listing | A real estate listing where the net proceeds of a sale or lease to the owner are specified and all above that figure is the broker's commission; this is an illegal arrangement in some states. |
| Net Profit | The excess of income after costs and expenses of a business are deducted. |
| Net Rentable Area | The amount of a building that is available for rental to tenants, expressed in square feet. |
| Net Working Capital | Current assets less current liabilities. |
| Net Worth | The difference between total assets and total liabilities. |
| Net, Safety, | See Safety Net. |
| Net, Tennis | See Tennis Net. |
| Neutral | 1. Without color; achromatic. 2. Being neither acid nor alkaline. 3. Not electrically live. 4. Neutral Arbitrator. |
| Neutral Arbitrator | An arbitrator not controlled by or biased in favor of any party; also called a Neutral. |
| Neutral Axis | The line on a member cross-section on which the bending moment is zero. |
| Neutral Conductor | The neutral conductor is a grounded conductor; the insulation on a neutral conductor is colored white or a natural gray. |
| Neutral Flame | A gas flame wherein the portion of oxygen and the welding gas used is neither oxidizing nor reducing. |
| Neutral wire | Usually color-coded white, this carries electricity from an outlet back to the service panel. Also see hot wire and ground. |
| Neutralizer | Substance used to counteract acids in refrigeration system. |
| Neutron | That part of an atom core which has no electrical potential; electrically neutral. |
| New England Method | See Pick and Dip. |
| Newel | 1. The principal post of the foot of a staircase. 2. The central support of a winding flight of stairs. |
| Newel post | The large starting post to which the end of a stair guard railing or balustrade is fastened. |
| Newell | Parent company of a host of blind/shade fabricators, including Levolor, Del Mar, LouverDrape, Joanna, Kirsch, and others. (29 East Stephenson Street, Freepoint, IL 61032) |
| Newport 1" miniblind | 8 gauge contract aluminum miniblind made by Levolor |
| Newton | An SI unit of force that is of such size that under its influence a body whose mass is one kilogram would experience an acceleration of one meter per second per second. |
| NFIP | National Flood Insurance Program. |
| NFMA | National Fan Manufacturers' Association. |
| NFoPA | Now known as AFPA. |
| NFPA | National Fire Protection Association. |
| NGA | National Glass Association. |
| NGR Stain | See Non-Grain-Raising Stain. |
| NHPMA | The Northern Hardwood and Pine Manufacturers Association. |
| NIBS | National Institute of Building Sciences. |
| NIC | Not in Contract. |
| Niche | Either a curved or square recess in a wall, dependent on the architecture and the use for which it is intended; used for housing statues, vases, telephones, or door chimes. |
| Nickel | A malleable ductile silver-white metallic element, used in special steels, magnetic alloys, and as a catalyst. |
| Nickel Silver | A silver-white alloy of copper, zinc, and nickel. |
| Nickel Steel | A steel alloy containing nickel as its principal alloying element. |
| Night Depository | An opening in an exterior wall of a structure or building that allows goods or materials to be delivered to a business after it has closed. |
| NIMBY | Not In My Back Yard, said in opposition to proposals to establish desirable developments, such as schools or hospitals, too close to one's own property. |
| Nineteen-Inch Selvage | A prepared roofing sheet with a 17 inch granule-surfaced exposure and a nongranule-surfaced 19 inch selvage edge; this material is also called a Split Sheet, SIS or as Wide-Selvage Asphalt Roll Roofing Surfaced with Mineral Granules. |
| NIOSH | National Institute for Occupational Safety and Health. |
| Nipple | Short length of pipe with male threads on both ends. |
| Nipple, Bushed | See Bushed Nipple. |
| Nipple, Offset | See Offset Nipple. |
| NIST | National Institute of Standards & Technology. |
| Nitrocellulose | Used extensively in making lacquer, is prepared from cellulose (cotton linters) by treatment with chemicals; see Cellulose Nitrate. |
| Nitrogen Dioxide | Mildly poisonous gas (NO2) often found in smog and automobile exhaust fumes. |
| NLGA | The National Lumber Grades Authority. |
| No-Fines Concrete | A concrete mixture in which only the coarse gradation (3/8 to 3/4 inch normally) of aggregate is used. |
| No-Frost Freezer | Low-temperature refrigerator cabinet in which no frost or ice collects on freezer surfaces or materials stored in cabinet. |
| No-Hub Pipe | Pipe usually manufactured of cast iron, which is fabricated without hubs and coupled together by a fastener of stainless steel and rubber. |
| Noble Gas | Any gaseous element of a group that almost never combine with other elements, consisting of helium, neon, argon, krypton, xenon, and radon; also called the Inert Gases or the Rare Rases. |
| NOFMA | National Oak Flooring Manufacturers' Association. |
| Nogging | The filling of brick between the roof rafters from the wall plate to roof boards for making the building wind tight. |
| Noil | A by-product in worsted yarn manufacture, consisting of short wool fibers, less than a determined length, which are combed out. |
| Noise | Any undesired sound. |
| Noise Reduction | 1. The reduction in sound pressure level caused by making some alteration to a sound source. 2. The difference in sound pressure level measured between two adjacent rooms caused by the transmission loss of the intervening wall. |
| Noise Reduction Coefficient (NRC) | A relative numerical expression of the ability of a material to absorb sound. |
| Nomenclature | Systematic naming; the terminology of a science. |
| Nominal Dimension | 1. The named size; compare with Actual Size. 2. An approximate rough cut dimension assigned to a piece of material as a convenience in referring to the piece, such as 2 by 4 or 500 pound. 3. The stated size of a piece of lumber; its actual size is smaller |
| Nominal Size | The named size, for example the nominal size of a wood stud is 2- by 4- inches while the actual size is less. The nominal size of a concrete block is 4- by 8- by 16-inch while the actual size is less. |
| Nomogram | A graphic representation consisting of three or more lines calibrated to scale and arranged so that a straightedge connecting known values on two lines will intersect unknown values on one or more other lines. |
| Non-Agitating Unit | A truck mounted unit for transporting ready- mixed concrete short distances, not equipped to provide agitation (slow mixing) during delivery. |
| Non-Automatic | Non-automatic means that the implied action requires personal intervention for its control; see Automatic; as applied to an electric controller, non- automatic control does not necessarily imply a manual controller, but only that personal intervention is |
| Non-Bearing Wall | A wall that carries no superimposed load; it could be removed without any structural effect on the remaining building. |
| Non-Code Installation | Functional refrigerating system installed where there are no local state or national refrigeration codes in force. |
| Non-Destructive Testing | Testing of building materials in a manner that does not destroy the material. |
| Non-Drying Oils | Oils which are unable to take up oxygen from the air and change from a liquid to a solid state; mineral oils are non-drying oils. |
| Non-Evaporable Water | The water in concrete which is irremovable by over drying; chemically combined during cement hydration. |
| Non-Ferrous Metal | A metal that does not contain iron. |
| Non-Grain-Raising Stain | Wood stain which does not raise the grain of the wood; NGR Stain; made by dissolving dyes such as used in making water stains in special solvent instead of water. |
| Non-Load Bearing Partition | A structurally non-essential interior wall assembly for compartmentalizing floor space. |
| Non-Metallic Tubing | A round sheath product, of round cross-section, fabricated from a moisture-resistant, flame-retardant material. |
| Non-Pressure Drainage | Means gravity flow drainage in which the sloping pipes are not filled to capacity. |
| Non-Rising Pin | See Fast Pin Hinge. |
| Non-Shrink Grout | Cementitious or epoxy based mix used to fill gap created between bearing components or base plates and foundation or other supporting element. |
| Non-Shrink Grout, Nonmetallic | Nonmetallic Non-Shrink Grout. |
| Non-Slip Terrazzo | A mixture of marble chips and portland cement on a portland cement and sand body, which has been roughened with iron fillings, carborundum powder or indented while it is wet. |
| Non-Slip Tile | Tile having greater non-slip characteristics due to an abrasive admixture, abrasive particles in the surface, grooves or patterns in the surface or because of natural non-skid surface characteristics. |
| Non-Volatile | Portion of a product which does not evaporate at ordinary temperature. |
| Nonaxial | In a direction not parallel to the long axis of a structural member. |
| Nonbearing | Not carrying a load. |
| Nonbearing Partition | A partition which extends from floor to ceiling but which supports no load other than its own weight. |
| Noncohesive soil | Soil particles that have no natural resistance to being pulled apart at their point of contact, for example, silt, sand, and gravel. |
| Noncombustible | Any material which will neither ignite nor actively support combustion in air at a temperature of 1200° F. when exposed to fire. |
| Noncondensable Gas | Gas which does not change into a liquid at operating temperatures and pressures. |
| Nonconforming Use | Use of land that is not in conformance with the zoning code; applies mainly to pre-existing uses when new zoning is enacted; the non- conforming use may remain as long as it is continuous; upon interruption, the non- conforming use may not continue. |
| Nonflammable | Incombustible, will not burn; opposite of flammable or inflammable. |
| Nonfrosting Evaporator | Evaporator which never collects frost or ice on its surface. |
| Nonmetallic Non-Shrink Grout | Nonmetallic cementitious or epoxy based mix used to fill gap created between bearing components or base plates and foundation or other supporting element. |
| Nonrecourse Mortgage | One in which the borrower has no personal liability, the lender's sole remedy being to foreclose on the property in the event of a default. |
| Nontoxic | Not poisonous. |
| Nonvitreous | Non-vitrified; that degree of vitrification evidenced by relatively high water absorption, usually more than 10 percent water absorption, except for floor and wall tile which are considered non-vitreous when water absorption exceeds 7 percent. |
| Norm | 1. The standard or principle set by the average of a large group in the same trade or profession. 2. An authoritative standard or model. |
| Normal Charge | Thermal element charge which is part liquid and part gas under all operating conditions. |
| Normal Consistency | Of gypsum plaster or gypsum concrete, the number of milliliters of water per 100 grams of gypsum plaster or gypsum concrete required to produce a mortar or a slurry of specified fluidity. |
| Normal Fault | A fault under tension where the overlying block moves down the dip or slope of the fault plane. |
| Normal Loading | A design load that stresses a member or fastening to the full allowable stress tabulated; this loading may be applied for approximately 10 years, either continuously or cumulatively, and 90 percent of this load may be applied for the remainder of the life |
| Normal Weight Concrete | Concrete having a hardened density of approximately 150 pcf which is made from aggregate of approximately the same density. |
| Norman Brick | A brick with 2-3/4 by 4 by 12 inch dimensions. |
| North American Insulation Manufacturers Association (NAIMA) | 44 Canal Center Plaza, #310, Alexandria, Virginia 22314, (703) 684-0084. |
| North Pole | 1. The northernmost point of the earth's axis of rotation. 2. The pole of a magnet that points to the north. |
| Northeastern Lumber Manufacturers Association, The (NELMA) | 4 Fundy Road, Falmouth, Maine 04105. |
| Northern Hardwood and Pine Manufacturers Association, The (NHPMA) | |
| Nosing | 1. The projecting forward edge of a stair tread; the part of a stair tread which projects over the riser. 2. Any similar projection. 3. The rounded edge of a board. |
| Nosing, Rubber | See Rubber Nosing. |
| Not in Contract (NIC) | Something shown on contract drawings, usually for reference, but not to be included in the construction contract. |
| Notary Public | One authorized by law to acknowledge and certify documents and signatures; a notary. |
| Notch | A crosswise rabbet at the end of a board. |
| Notched Trowel | 1. A tile setter's tool consisting of a trowel with serrated edges; used to spread bonding materials; depth of application is regulated by the size and spacing of the teeth. 2. A similar tool used by applicators of resilient flooring to spread adhesive. |
| Note | A formal document showing the existence of a debt and stating the terms of repayment. |
| Note | A written promise to pay a certain amount of money at a certain time. |
| Note Payable | Amount owed because of a promissory note given to a creditor. |
| Note Receivable | A promissory note given by a customer to pay a definite sum to the business at a specific future time. |
| Notice | Delivery of information to a party |
| Notice of Cessation | A written notice filed by the owner or owner's agent signifying that no labor has been performed on the project for a specific period of time (such as 60 days) and establishing the time remaining to exercise lien rights by all parties concerned. |
| Notice of Completion | A written notice filed by the owner or owner's agent signifying completion of a project and establishing the time remaining to exercise lien rights by all parties concerned. |
| Notice of Nonresponsibility | A notice which, if properly recorded and posted on the premises, relieves the owner from the effects of mechanics liens for work and materials not ordered by the owner, usually ordered by lessees. |
| Notice to Pay Rent or Quit | A legal notice to a defaulting tenant, a prerequisite to eviction. |
| Notice to Proceed (NTP) | A written notice to a contractor to proceed with the work of the contract. |
| Nourishment | The process of replenishing a beach. It may be brought about naturally, by accretion due to the longshore transport, or artificially, by the deposition of dredged materials. |
| Novation | The substitution of a new legal obligation for an old one. |
| Nozzle | The part of a heating system that sprays the fuel of fuel-air mixture into the combustion chamber. |
| NPA | National Particleboard Association. |
| NPVLA | National Paint & Coatings Association. |
| NRC | Noise Reduction Coefficient. |
| NRCA | National Roofing Contractors Association. |
| NRMCA | National Ready Mixed Concrete Association. |
| NRP | Non-Rising Pin. |
| NSF | National Sanitation Foundation. |
| NSPI | National Spa & Pool Institute. |
| NTIS | National Technical Information Service. |
| NTMA | National Terrazzo and Mosaic Association. |
| NTP | Notice to Proceed. |
| NTS | Not to Scale. |
| Nuclear Density Meter | An instrument for the non-destructive determination of the density and moisture content of material using a radioactive source for its operation. |
| Nuclear Meter | An instrument for detecting and measuring moisture. |
| Nuisance | A condition of or on real property that damages neighboring persons or property. |
| Nurse Station | An area in a hospital where nurses congregate and medical materials and records are stored. |
| Nurse Station Indicator | A signaling device at a nurses station activated by patients needing assistance from nurses. |
| Nursing Care Facility | Any institution which provides nursing care services to persons needing constant care and attention on a 24-hour basis; a nursing home, nursery, long term facility, convalescent home. |
| Nut | A small square or hexagonal flat piece of metal or other material with a threaded hole through it for screwing on the end of a bolt to secure it. |
| Nut, Hex | See Hex Nut. |
| NuWood | 2" faux wood blind made of a wood/vinyl alloy. Made by Levolor. |
| NW | No Weather; see Grade NW Brick. |
| NWMA | National Woodwork Manufacturers' Association. |
| NWWDA | National Wood Window & Door Association. |
| Nylon | Any of various synthetic polyamide fibers with tough, lightweight, elastic properties, used in industry and for textiles. |
| Nylon Carpet | A carpet made from synthetic nylon fibers. |
| Nylon Plastics | Plastics based on resins composed principally on long-chain synthetic polymeric amide which has recurring amide groups as an integral part of the main polymer chain. |