Roofing Terms M – O
- -M-
- Mansard
- a decorative steep-sloped roof on the perimeter of a building.
- Mansard roof
- a steeper roof that terminates into a flat roof at its high point.
- Masonry
- construction, usually set in mortar, of natural building stone or manufactured units, such as brick, concrete block, adobe, glass block, tile, manufactured stone or gypsum block.
- Mastic
- a thick adhesive material used as a cementing agent for holding waterproofing membrane in place. (see Asphalt Roof Cement).
- Mat
- a thin layer of woven, non-woven, or knitted fiber that serves as reinforcement to a material or membrane.
- Mat slab
- a concrete slab designed with reinforcement to resist the uplift forces created by hydrostatic pressure.
- Material safety data sheets (MSDS)
- a written description of the chemicals in a product and other pertinent data, including such things as safe handling and emergency procedures. In accordance with OSHA regulations, it is the manufacturer’s responsibility to produce an MSDS and the employers responsibility to communicate its contents to employees.
- Mechanical damage
- in SPF-based roofing, physical damage to a completed SPF-based roof system not caused by normal wear and tear.
- Mechanically fastened membranes
- generally used to describe membranes that have been attached at defined intervals to the substrate.
- Membrane
- a flexible or semi-flexible roof covering or waterproofing whose primary function is to exclude water.
- Metal
- any of various opaque, fusible, ductile and typically lustrous substances that are good conductors of electricity and heat. The NRCA Roofing and Waterproofing Manual—Fifth Edition Glossary 991
- Metallic waterproofing
- consist of finely graded iron particles combined with an oxidizing catalyst. When mixed with water (or water, cement, and sand), the finely distributed particles expand, creating a waterproof layer that becomes a part of the surface to which it is applied.
- Metal rain collar
- a metal counterflashing used to wrap a penetration and prevent water infiltration though the top of the penetration base flashing.
- Meter
- unit of length measurement in the metric system; 1 meter is equal to 39.37 inches.
- Metal roof panel
- an interlocking metal sheet having a minimum installed weather exposure of 3 square feet (279000 mm2 or 0.28 m2) per sheet.
- Metal roof shingle
- an interlocking metal sheet having an installed weather exposure less than 3 square feet (279000 mm2 or 0.28 m2) per sheet.
- Mil
- a unit of measure, one mil is equal to 0.001 inches, or 25.4 micrometers (µm), often used to indicate the thickness of a roofing membrane.
- Mildew
- a superficial growth produced on organic matter or living plants by fungi.
- Millimeter
- a unit of measure equal to one thousandth (0.001) of a meter, or 0.03937 inches.
- Mineral fiber
- insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.
- Mineral granules
- see Granules.
- Mineral stabilizer
- a fine, water-insoluble inorganic material, used in a mixture with solid or semi-solid bituminous materials.
- Mineral-surfaced roofing
- roofing materials whose surface or top layer consists of a granule-surfaced sheet.
- Mineral-surfaced sheet
- a roofing sheet that is coated on one or both sides with asphalt and surfaced with mineral granules.
- Miter joint
- a joint between two members at an angle to each other; each member is cut at an angle equal to half the angle of the junction; usually the members are at right angles to each other.
- Model (building) codes
- a compilation of standards or codes established to provide uniformity in regulations pertaining to building construction.
- Modified bitumen
- (1) a bitumen modified by including one or more polymers (e.g., atactic polypropylene, styrene butadiene styrene, etc.); (2) composite sheets consisting of a polymer modified bitumen often reinforced with various types of mats or films and sometimes surfaced with films, foils or mineral granules.
- Moisture contour map
- a map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed.
- Moisture relief vent
- a venting device installed through the roofing membrane to relieve moisture vapor pressure from within the roofing system.
- Moisture scan
- the use of a mechanical device (capacitance, infrared, or nuclear) to detect the presence of moisture within a roof assembly. (see Non-destructive Testing).
- Mole run
- a meandering ridge in a roof membrane not associated with insulation or deck joints.
- Monolithic
- formed from or composed of a single material; seamless.
- Monomer
- a low-molecular-weight substance consisting of molecules capable of reacting with like or unlike molecules to form a polymer. The NRCA Roofing and Waterproofing Manual—Fifth Edition 992 Glossary
- Mop-and-flop
- an application procedure in which roofing elements (insulation boards, felt plies, cap sheets, etc.) are initially placed upside down adjacent to their ultimate locations; coated with adhesive or bitumen; and turned over and adhered to the substrate.
- Mopping
- the application of hot bitumen with a mop or mechanical applicator to the substrate or plies of a bituminous membrane. There are four types of mopping.
- Solid mopping: a continuous coating.
- Spot mopping: bitumen is applied roughly in circular areas, leaving a grid of unmopped perpendicular areas.
- Sprinkle mopping: bitumen is shaken onto the substrate from a broom or mop in a random pattern.
- Strip mopping: bitumen is applied in parallel bands.
- Mud cracking
- surface cracking resembling a dried mud flat.
- Mud slab
- a layer of concrete, typically 2 inches (50 mm) to 6 inches (150 mm) thick, used as the substrate for membrane waterproofing.
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- -N-
- Nailer
- (sometimes referred to as blocking) a piece or pieces of dimensional lumber and/or plywood secured to the structural deck or walls, which provide a receiving medium for the fasteners used to attach membrane or flashing.
- NBP
- acrylonitrile butadiene polymer blend. One proprietary NBP membrane is commonly referred to as nitrile butadiene copolymer.
- Negative side waterproofing
- an application wherein the waterproofing system and source of hydrostatic pressure are on opposite sides of the structural element.
- Neoprene
- a synthetic rubber (polychloroprene) used in liquid and sheet-applied elastomeric roof membranes or flashings.
- Nesting
- (1) the installation of new metal roof deck directly on top of existing metal roof deck; (2) a method of reroofing with new asphalt shingles over existing shingles in which the top edge of the new shingle is butted against the bottom edge of the existing shingle.
- Net free vent area
- the area (measured in square inches) open to unrestricted air flow and commonly used as a yardstick to measure relative vent performance; the area of the opening of a vent minus the area displaced by the screening material.
- Newton (N)
- SI unit of measure for force.
- Night seal (or night tie-in)
- a material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. Usually removed when roofing application is resumed.
- NIST
- National Institute of Standards and Technology
- Nitrile alloy
- an elastomeric material of synthetic nonvulcanizing polymers.
- Nitrile rubber
- a membrane whose predominant resinous ingredient is a synthetic rubber made by the polymerization of acrylonitrile with butadiene.
- Noble metal
- a metal that readily receives electrons from an anodic metal (see Galvanic Series).
- No-cutout shingles
- shingles consisting of a single solid strip with no cutouts.
- Nondestructive testing (NDT)
- a method to evaluate the disposition, strength or composition of materials or systems without damaging the object under test. Typically used to evaluate moisture content in roofing assemblies, the three common test methods are electrical capacitance, infrared thermography and nuclear back-scatter. The NRCA Roofing and Waterproofing Manual—Fifth Edition Glossary 993
- Nonflammable
- not easily ignited and not burning rapidly if ignited.
- Nonfriable
- a material that, when dry, cannot be crumbled, pulverized or reduced to powder by hand pressure.
- Nonoxidizing
- a material which resists oxidation in exterior exposures or accelerated weathering.
- Non-traffic bearing
- for waterproofing purposes, a membrane system requiring some form of protection barrier and wearing surface.
- Nonvolatile content
- the portion of a coating that does not evaporate during drying or curing under specified conditions, comprising the binder and, if present, the pigment. (The percent volatile content is obtained by subtracting the nonvolatile content from 100.).
- Nonwoven fabric
- a textile structure produced by bonding or interlocking of fibers, or both, accomplished by mechanical, chemical, thermal, or solvent means and combinations thereof.
- NRCA
- National Roofing Contractors Association.
- Nuclear hydrogen detection (NHD) meter
- a device that contains a radioactive source to emit high velocity neutrons into a roof system. Reflecting neutrons are measured by a gauge that is used to detect hydrogen; the quantity of hydrogen detected may be linked to the pressure of water.
- Nylon
- generic name for a family of polyamide polymers, used as a scrim in some fabric-reinforced sheeting.
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- -O-
- Off-ratio foam
- SPF that has excess isocyanate or resin. Off-ratio will not exhibit the full physical properties of normal SPF.
- Open time
- the period of time after an adhesive has been applied and allowed to dry, during which an effective bond can be achieved by joining the two surfaces.
- Open valley
- a method of valley construction in which the steep-slope roofing on both sides are trimmed along each side of the valley, exposing the metal valley flashing.
- Orange peel surface texture
- in SPF roofing, a condition of the foam in which the surface shows a fine texture and is compared to the exterior skin of an orange. This surface is considered acceptable for receiving a protective coating.
- Organic
- being or composed of hydrocarbons or their derivatives, or matter of plant or animal origin.
- Organic felt
- an asphalt roofing base material manufactured from cellulose fibers.
- Organic shingle
- an asphalt shingle reinforced with material manufactured from cellulose fibers.
- ORNL
- Oak Ridge National Laboratory.
- Osmosis
- movement of a solvent through a semipermeable membrane into a solution of higher solute concentration that tends to equalize the concentration of solute on the two sides of the membranes.
- Overflow drainage
- component in a roof drainage system used to protect the roof against damage from a water load imposed by blocked or partially blocked primary drainage system; e.g., overflow scupper, overflow interior drain.
- Overspray
- undesirable depositions of airborne spray.
- Overspray surface texture
- in SPF roofing, a condition of the foam in which the surface shows a linear coarse textured pattern and/or a pebbled surface. This surface is generally downwind of the sprayed polyurethane path and, if severe, unacceptable for proper coating coverage and protection.
- Ozone
- a triatomic form of oxygen that is a bluish gas of pungent odor; is formed naturally in the upper atmosphere by a photochemical reaction with solar ultraviolet radiation. The NRCA Roofing and Waterproofing Manual—Fifth Edition 994 Glossary
- Ozone resistance
- the ability of a material to resist the deteriorating effects of ozone exposure.
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