Mat: A thin layer of woven, non-woven, or knitted fiber used to reinforce a material.
Material Safety Data Sheets (MSDS): Written descriptions of the chemicals in a product provided by the products manufacturer. MSDS also contain other information such as emergency procedures and safe handling.
MBMA: Metal Building Manufacturers Association
MCA: Metal Construction Association
Mechanical Damage: Damage to a roof by means of items puncturing or otherwise unnecessarily penetrating the roof system or any of its components. Screws or nails stuck in the roof and heel marks along base flashings are examples of mechanical damage.
Mechanical Fasteners: Devices such as screws, plates, battens, nails, or other materials that are used to secure roofing materials.
Membrane: The portion of the roofing system that serves as the waterproofing material. Can be composed of one material or several materials laminated together.
Metal Flashing: Roof components made from sheet metal that are used to terminate the roofing membrane or material along roof edges. Metal flashings are also used in the field of the roof around penetrations.
Meter: Metric unit of length measurement equal to 39.37 inches.
Mil: A unit of measure equal to 0.001 inches (1/1000 in.) used to indicate the thickness of a roofing membrane.
Mildew: A superficial coating or discoloration of organic materials caused by fungi, especially under damp conditions.
Millimeter: Metric unit of measure equal to one thousandth (0.001) of a meter, or 0.03937 inches.
MIMA: Mineral Insulation Manufacturers Association
Mineral Fiber: Inorganic fibers of glass or rock.
Mineral Granules: See Granules.
Mineral-Surfaced Roofing: Roofing materials with a top surface consisting of mineral granules.
Miter: The joint made by two diagonally cut pieces put together.
Model Codes: A group of codes and standards accepted by more than one of the Building Code regulatory agencies such as SBCCI, BOCA, and ICBO
Modified Bitumen: a bitumen modified by one or more polymers such as Atactic Polypropylene (APP), styrene butadiene styrene (SBS).
Moisture Relief Vent: A vent installed through the roofing membrane to relieve moisture vapor pressure that has been trapped within the roofing system.
Moisture Scan: A survey of a roof specifically to detect the amount of moisture present in the roof system. Devices used in moisture surveys can be capacitance meters, infrared cameras, and nuclear scanners. Infrared scans can be done from the air or on the surface of the roof. Capacitance and nuclear scans are done on the roof surface. It is argued that the most accurate scans are done from the surface of the roof with the most accurate of these being nuclear scans.
Mole Run: A term used to describe a ridge in a roof membrane that is not the result of improper deck or insulation joints.
Monolithic: Used to describe something without seams; formed from a single material.
Monomer: A simple molecule that can combine with other to form a polymer.
Mop-and-Flop: A roofers term where the back side of a roofing material is mopped, then the piece is turned over and set in place.
Mopping: To apply hot asphalt or coat tar using a hand mop or mechanical applicator.
Mud Cracking: Surface cracking of a material that looks similar to dried, cracked mud.
Multiple Coats: More than one layer of coating applied to a substrate.