- Maintenance - A regular process of inspection, cleaning and minor repairs of buildings elements and exterior systems. Cleaning is for normal activities for those items as required on a regular basis, such as leaves from gutters and drains in the fall, and cleaning lint from dryer vents. Minor repairs encompass small projects that reinstate failed elements such as areas of cracked caulking or peeling paint.
- Material Safety Data Sheet (MSDS) - A standard formatted information sheet prepared by a material manufacturer which describes the potential hazards, physical properties, and procedures for safe use of a material.
- Membrane - A flexible or semi-flexible roof covering whose primary function is the exclusion of water.
- Methylene Diphenyl Diisogyanate (MDI) - Component A in spray polyurethane foam. An organic chemical compound having two reactive
isocyanate (-N=C=O) groups. It is mixed with the B component to form polyurethane
- Micron - One inch equals 25,400 microns (100 microns = 0.0039 mils)
- Mil - One-thousandth of an inch; 0.001 inch (0.025mm). A unit used to measure coating thickness.
- Monolithic - Formed from or composed of a single material; seamless.
- Neoprene Rubber - A synthetic rubber having physical properties closely resembling those of natural rubber. Made by polymerization of
- Night Seal - A material and or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in
place from water penetration. May be removed when roofing application is resumed.
- Non-Breathing Membrane - A membrane material that has a significantly greater resistance to the diffusion of water vapor than the other materials with which it is used.
- Non-Ferrous Metal - All metals that are not iron compounds, i.e., copper, lead, gold, silver, and aluminum. These metals are non-magnetic.
- Non-Flammable - Liquid having no measurable flash point.
- Non-Oxidizing - A material that resists oxidation in exterior exposures or accelerated weathering.
- Non-Volatile Content - That portion of a coating material that does not evaporate under normal ambient conditions. (For Comparison See SOLIDS CONTENT)
- NRCA - National Roofing Contractors Association.
- Off-Ratio Foam - Polyurethane which has a lack of isocyanate or resin. Off-ratio foam will not exhibit the full physical properties of normal foam.
- Orange Peel Surface Texture - The surface texture of polyurethane foam resembling that of an orange peel.
- Organic - Compounds containing carbon.
- Orifice - An opening or aperture. The opening in the tip of a spray gun.
- Overspray - (1) Airborne spray loss of polyurethane foam or coatings.
(2) Undesirable depositions of airborne spray loss.
- Overspray Surface Texture - The surface shows a linear coarse textured pattern and/or a pebbled surface. This surface is generally downwind of the sprayed polyurethane path and is unacceptable for proper coating coverage and protection, if severe.
- Pass - The amount of coating or polyurethane foam applied by moving the gun from side to side and moving away from fresh material. A pass is delineated by its width, length and thickness.
- Pass Lines - The overlapping of the polyurethane foam or coating as the newly applied material ties into the previous pass.
- Peel Strength - The average force (or force per unit width) required to peel a membrane or other material from the substrate to which it has been bonded.
- Peeling - Top-coating film inadequately bonded with undercoats resulting in partial delamination or detachment of final coat.
- Personal Protective Equipment (PPE) - Specialized clothing or equipment worn by employees for protection against health and safety hazards. Personal protective equipment is designed to protect many parts of the body, i.e., eyes, head, face, hands, feet and ears.
- pH - A measure of acidity/alkalinity of aqueous mixtures. A measure of pH 7 is neutral, lower is more acidic, higher is more alkaline.
- Pigment - Fine solid particles dispersed in a coating to impart color.
- Pinhole - A small hole in a mastic, coating, or polyurethane foam.
- Plasticizer - A substance added to a plastic or coating to increase its flexibility or elongation.
- Polymer - A substance consisting of high molecular weight chemical compounds characterized by chains of repeating simpler units.
- Polyol - Polyol is the main ingredient of the resin component that reacts with the isocyanate to form polyurethane.
- Polyurethane Coatings - A one or two part coating that contains polyisocyanate monomer and a hydroxyl containing resin, which react during cure to form polyurethane elastomeric.
- Polyurethanes - A compound based on the reaction of various isocyanates and various polyol resins. These compounds or polymers can create rigid foams, flexible foams, elastomeric coatings or structural resins and many other forms. They are either an aromatic or aliphatic polyurethane.
- Primer - The first layer of coating applied to a surface to improve the adhesion of subsequently applied materials or to inhibit corrosion.
- Proportioner - The basic pumping unit for spraying polyurethane foam or two component coating systems. Consists of two positive displacement pumps designed to dispense two components at a precisely controlled ratio.
- PSI - Pounds per square inch.
- Psychrimeter - A device for measuring ambient humidity by employing a dry bulb thermometer and a wet bulb thermometer.
- Purge - To cleanse or remove liquid materials from equipment or hoses.