Mansard roof    A roof with two sloping planes of different pitch on each of its four sides. The lower plane is steeper than the upper, and may be almost vertical. See also gambrel roof.
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 TM 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 that may use less wood. See also 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.
Masonry primer    An asphalt-based primer used to prepare masonry surfaces for bonding with other asphalt products.
Masonry     - Stone, brick, concrete, hollow-tile, concrete-block, gypsum-block or other similar building units or material or a combination of the same, bonded together with mortar to form a wall, pier, buttress or similar mass.
Mastic     - A pasty material used as cement (as for setting tile) or protective coating (as for thermal insulation or waterproofing). See “asphalt plastic cement.”
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.
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.
Molding    : A decorative strip, usually of wood, having a curved or projecting surface used for ornamental purposes.
Mullion     - A vertical bar or divider in the frame between windows, doors or other openings.