Main Vent (or Stack): Principal vent to which branch vents may be connected. See Stack.
Male IPS: Pipe connection where the threads are on the outside of the fitting. See MIP.
Male Threads: See MIP.
Mansard Roof: A roof which rises by inclined planes from all four sides of a building. The sloping roofs on all four sides have two pitches, the lower pitch usually very steep and the upper pitch less steep.
Mantel: The shelf above a fireplace. Also used in referring to the decorative trim around a fireplace opening.
Manufactured Wood: A wood product such as a truss, beam, Glue Lam or joist which is manufactured out of smaller wood pieces and glued or mechanically fastened to form a larger piece. Often used to create a stronger member which may use less wood. See Oriented Strand Board.
Manufacturers Specifications: The written installation and/or maintenance instructions which are developed by the manufacturer of a product and which may have to be followed in order to maintain the product warrantee.
Mason's Hammer (Bricklayer's Hammer): Tool shaped like a chisel to trim brick or stone.
Masonry: Stone, brick, concrete, hollow-tile, concrete block, gypsum block, or other similar building units or materials or a combination of the same, bonded together with mortar to form a wall, pier, buttress, or similar mass.
Masonry Primer: An asphalt-based primer used to prepare masonry surfaces for bonding with other asphalt products.
Mastic: Heavy-consistency compound that may remain adhesive and pliable with age. Is typically a waterproof compound applied to exterior walls and roof surfaces.
Matched Lumber: Lumber that is dressed and shaped on one edge in a grooved pattern and on the other in a tongued pattern.
Maximum Occupancy Load: The maximum number of people permitted in a room. It is measured per foot for each width of exit door. The maximum is 50 per foot of exit.
Mechanics Lien: A lien on real property, created by statue in many years, in favor of persons supplying labor or materials for a building or structure for the value of labor or materials supplied by them. In some jurisdictions, a mechanics lien also exists for the value of professional services. Clear title to the property cannot be obtained until the claim for the labor, materials, or professional services is settled. Timely filing is essential to support the encumbrance, and prescribed filing dates vary by jurisdiction.
Melt Point: The temperature at which solid asphalt becomes a liquid.
Membrane: A generic term relating to a variety of sheet goods used for certain built-up roofing repairs and application.
Metal Edge: Brake metal or metal extrusions which are secured at the perimeter of the roof to form a weather-tight seal.
Metal Lath: Sheets of metal that are slit and drawn out to form openings. Used as a plaster base for walls and ceilings and as reinforcing over other forms of plaster base.
Microlam: A manufactured structural wood beam. It is constructed of pressure and adhesive bonded wood strands of wood. They have a higher strength rating than solid saw lumber. Normally comes in l ½" thickness' and 9 ½", 11 ½" and 14" widths.
Migration: Spreading or creeping of a constituent of a compound onto/into adjacent surfaces. See bleeding.
Mil Thickness: Measurement used to determine thickness of a coating. 1 mil = .001 inch (1/1000).
Milar (Mylar): Plastic, transparent copies of a blueprint.
Millwork: Generally all building materials made of finished wood and manufactured in millwork plants and planing mills are included under the term "millwork." It includes such items as inside and outside doors, window and doorframes, blinds, porch work, mantels, panel work, stairways, moldings, and interior trim. It normally does not include flooring, ceiling, or siding.
Mineral Spirits: A by-product of petroleum, clear in color, used as a solvent for asphalt coatings.
Mineral Stabilizers: Finely ground limestone, slate, traprock or other inert materials added to asphalt coatings for durability and increased resistance to fire and weathering.
Mineral-Surfaced Roofing: Asphalt shingles and roll roofing that are covered with granules.
Minispread: A smaller variation of a widespread faucet with separate spout and handles designed small enough to fit 4" center-to-center faucet holes.
MIP (Male Iron Pipe): Standard threads that are on the outside of a pipe or fitting.
Miter Joint: The joint of two pieces at an angle that bisects the joining angle. For example, the miter joint at the side and head casing at a door opening is made at a 45° angle.
Mixing Valve: A valve that mixes hot and cold water in the valve to obtain a set temperature prior to delivery.
Mobile Home Aluminum Roof Coating: Durable one-coat application prolongs the life of mobile home roofs while reflecting sun's rays and providing a decorative surface. Reduces energy costs.
Mock-Up Testing: Controlled air, water and structural performance testing of existing or new glazing systems.
Modified Bitumen Roof: A roof covering that is typically composed of a factory-fabricated composite sheet consisting of a copolymer-modified bitumen, often reinforced with polyester and/or fiberglass, and installed in one or more plies. The membrane is commonly surfaced with field-applied coatings, factory-applied granules or metal foil. The roofing system may incorporate rigid insulation.
Modulus: Stress at a given strain. Also tensile strength at a given elongation.
Moisture Content of Wood: Weight of the water contained in the wood, usually expressed as a percentage of the weight of the oven-dry wood.
Molding: A wood strip having a coned or projecting surface used for decorative purposes, e.g., door and window trim.
Monitor: A large structure rising above the surrounding roof planes, designed to give light and/or ventilation to the building interior.
Monopost: Adjustable metal column used to support a beam or bearing point. Normally 11 gauge or Schedule 40 metal, and determined by the structural engineer.
Mopping: In roofing, a layer of hot bitumen mopped between plies of roofing felt. Full mopping is the application of bitumen by mopping in such a manner that the surface being mopped is entirely coated with a reasonably uniform coating. Spot Mopping is the procedure of applying hot bitumen in a random fashion of small daubs, as compared to full mopping. Sprinkle mopping is a special application of installing insulation to the decks. It is done by dipping a roof mop into hot bitumen and sprinkling the material onto the deck. Strip Mopping is the application of bitumen in parallel bands.
Mortar Types: Type M is suitable for general use and is recommended specifically for masonry below grade and in contact with earth, such as foundations, retaining walls and walks. Type M is the strongest type. Type S is suitable for general use and is recommended where high resistance to lateral forces is required. Type N is suitable for general use in exposed masonry above grade and is recommended specifically for exterior walls subject to severe exposures. Type O is recommended for load-bearing walls of solid units where the compressive stresses do not exceed 100 lbs. per square inch and the masonry wall not be subjected to freezing and thawing in the presence of excessive moisture.
Mortgage: Loan secured by land.
Mortgage Broker: A broker who represents numerous lenders and helps consumers find affordable mortgages; the broker charges a fee only if the consumer finds a loan.
Mortgage Company: A company that borrows money from a bank, lends it to consumers to buy homes, then sells the loans to investors.
Mortgage Deed: Legal document establishing a loan on property.
Mortgage Origination Fee: A charge for work involved in preparing and servicing a mortgage application (usually one percent of the loan amount).
Mortgagee: The lender who makes the mortgage loan.
Mortise: A slot cut into a board, plank, or timber, usually edgewise, to receive tenon of another board, plank, or timber to form a joint.
Mud Cracks: Cracks developing from the normal shrinkage of an emulsion coating when applied too heavily.
Mudsill: A wood foundation member, usually a pressure treated 2x4 or 2x6, bolted to the foundation and on which other framing members can be attached.
Mullion: A vertical bar or divider in the frame between windows, doors, or other openings that supports and holds such items as panels, glass, sash, or sections of a curtain wall.
Muntins: Horizontal or vertical bars that divide the sash frame into smaller lights of glass. Muntins are smaller in dimensions and weight than mullions.
Muriatic Acid: Commonly used as a brick cleaner after masonry work is completed.
Mushroom: An unacceptable occurrence when the top of a caisson concrete pier spreads out and hardens to become wider than the foundation wall thickness.
NACHI Foundation: A Maryland based charitable organization funded by members of the National Association of Certified Home Inspectors.
Nailer: A piece of lumber secured to non-nailable decks and walls by bolts or other means, which provides a suitable backing onto which roof components may be mechanically fastened.
Natural Finish: A transparent finish which does not seriously alter the original color or grain of the natural wood. Natural finishes are usually provided by sealers, oils, varnishes, water-repellent preservatives, and other similar materials.
Neat Plaster: A base coat plaster which does not contain aggregates and is used where the addition of aggregates on the job is desired.
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.
Neoprene: A synthetic rubber having physical properties closely resembling those of natural rubber. It is made by polymerizing chloroprenes, which are produced from acetylene and hydrogen chloride.
Nesting: A method of re-roofing with new asphalt shingles over old shingles in which the top edge of the new shingles is butted against the bottom edge of the existing shingle tab.
Neutral Wire: Usually color-coded white, the neutral wire carries electricity from an outlet back to the service panel. Also see Hot Wire and Ground.
Newel: A post to which the end of a stair railing or balustrade is fastened. Also, any post to which a railing or balustrade is fastened.
Nipple: A short pipe installed between fittings. A pipe coupling that is threaded on both ends.
NM: A type of Romex cable (nonmetallic sheathed cable that contains several conductors). The cable, which is flame-retardant, is limited to use in dry locations only and cannot be exposed to excessive moisture.
NMC (Non Metallic Conduit): A type of Romex cable (nonmetallic sheathed cable that contains several conductors). NMC may be used in damp or corrosive locations as well as dry areas.
No-Cutout Shingles: Shingles consisting of a single, solid tab with no cutouts.
Nominal Size: Size used for identification only; not literal dimensions.
Non-Bearing Wall: A wall supporting no load other than its own weight.
Non-Destructive: A phrase describing a method of examining the interior of a component whereby no damage is done to the component itself.
Non-Drying (Non-Curing): A sealant that does not set up or cure. See Butyl.
Non-fibered Aluminum Roof Coating: Thin but efficient reflective barrier to reflect sun's harmful rays and prolong surface life. Also works on metal surfaces.
Non-Sag: A sealant formulation having a consistency that will permit application in vertical joints without appreciable sagging or slumping. This performance characteristic allows the sealant to be installed in a sloped or vertical joint application without appreciable sagging or slumping.
Non-Skinning: Descriptive of a product that does not form a surface skin.
Non-Staining: Characteristic of a compound that will not stain a surface.
Non-Veneer Panel: Any wood-based panel that does not contain veneer and carries an APA span rating, such as wafer board or oriented strand board.
Nonfibered Roof and Foundation Coating: Dual purposed, this thin-viscosity material doubles as a nonfibered roof or foundation coating.
Normal Slope Application: Method of installing asphalt shingles on roof slopes between 4 inches and 21 inches per foot.
Nosing: The projecting edge of a molding or drip. Usually applied to the projecting molding on the edge of a stair tread.
Notch: A crosswise rabbet at the end of a board.
Note: A formal document showing the existence of a debt and stating the terms of repayment.
Nozzle: The tubular tip of a caulking gun through which the compound is extruded.
Nuclear Meter: A device used to detect moisture by measuring slowed, deflected neutrons.
O-Ring: Round rubber washer or gasket that is compressed to create a watertight seal, typically in a compression fitting.
O. G. (or Ogee): A molding with a profile in the form of a letter S; having the outline of a reversed curve.
Oakum: Loose hemp or jute fiber that is impregnated with tar or pitch and used to caulk large seams or for packing plumbing pipe joints.
OD (Outside Diameter): A measurement of the diameter of a pipe as taken from the outside edge. A common method for sizing pipe.
Offset: A tubular component which permits the offsetting of a drainage run in the same basic direction.
Ohm's Law: States that, in a given electrical circuit, the amount at current in amps is equal to the pressure in volts divided by the resistance in ohms. The formula is: I (Current) = V voltage or V = I x R R resistance or R = V/I.
Ohmmeter: In electrical contracting, a device to measure the resistance across a load. They are never used on a live circuit. Used to track down broken wires.
Oil-Canning: The term describing distortion of thin-gauge metal panels which are fastened in a manner restricting normal thermal movement.
On Center (O.C.): A measurement term meaning a certain distance between like materials. Studs rafters, joists, and the like in a building placed at 16 inches O.C. will be laid out so that there is 16 inches from the center of one stud to the center of the next.
Open Hole Inspection: When an engineer (or municipal inspector) inspects the open excavation and examines the earth to determine the type of foundation (caisson, footer, wall on ground, etc.) that should be installed in the hole.
Open Valley: Method of valley construction in which shingles on both sides of the valley are trimmed along a chalk line snapped on each side of the valley. Shingles do not extend across the valley. Valley flashing is exposed.
Organic: A term designating any chemical compound which contains carbon and hydrogen.
Organic Felt: An asphalt roofing base material manufactured from cellulose fibers.
Oriented Strand Board (OSB, Chip Board, Wafer Board): A manufactured wood panel made out of 1"- 2" wood chips and glue. Often used as a substitute for plywood in the exterior wall and roof sheathing.
Outrigger: An extension of a rafter beyond the wall line. Usually a smaller member nailed to a larger rafter to form a cornice or roof overhang.
Overhang: That part of the roof structure which extends horizontally beyond the vertical plane of the exterior walls of a building.
Oxidize: To combine with oxygen in the air.