M,N,

Dictionary of Roofing Terms

If you would like to add a term to the list please feel free to e-mail us by clicking on the link above and we will add it for you.

Mansard: (1) A steep-sloped roof located at the perimeter of a building and usually used for decorative purposes. (2) The upper story formed by the lower slope of a mansard roof.

Mansard Roof: A steeper roof that terminates into a lower sloped roof at its high point.

Masonry: Refers to bricks, concrete, or concrete blocks.

Mastic: Heavy consistency compound that may remain adhesive and pliable with age. It is typically a waterproof compound applied to exterior walls and roof surfaces.

Mat: A thin layer of woven, non-woven, or knitted fibre used to reinforce a material.

Material Safety Data Sheets (MSDS): Written descriptions of the chemicals in a product provided by the product’s manufacturer. MSDS also contain other information such as emergency procedures and safe handling.

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. i.e. 0.001in=0.0254mm therefore 20 mils = 0.5mm, 40mils = 1mm etc.

Mildew: A superficial coating or discoloration of organic materials caused by fungi, especially under damp conditions.

Millimetre: Metric unit of measure equal to one thousandth (0.001) of a meter, or 0.03937 inches.

Mineral Fibre: Inorganic fibres of glass or rock.

Mineral-Surfaced Roofing: Roofing materials with a top surface consisting of mineral granules.

Mitre: The joint made by two diagonally cut pieces put together.

Moisture Relief Vent: A vent installed through the roofing membrane to relieve moisture vapour 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.

Monitor: A large structure rising above the surrounding roof planes, designed to give light and/or ventilation to the interior of the building.

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.

Multiple Coats: More than one layer of coating applied to a substrate.

NAHB: National Association of Home Builders

Nailer: A piece of timber, preferably treated, that is secured to the deck, walls, or to premanufactured curbs. Nailers are used to receive fasteners for roof membranes. Generally, nailers are installed wherever it is necessary to secure base flashings and edge metal. Also see Blocking.

Newton (N): In the meter-kilogram-second system, the unit of force required to accelerate a mass of one kilogram one meter per second per second (s².)

Night Seal: To temporarily seal the edge of a roof membrane in order to protect it from moisture entry. A.K.A. Night Tie-Off and Water Cut-Off.

Noble: In reference to metal, inert or inactive.

Non-Breathing Membrane: A membrane that does not permit water vapour or air to permeate it.

Non-Flammable: Material with no measurable flash point.

Non-Friable: Refers to a material’s inability to be crushed or pulverized into a powder.

Non-Volatile Content: The portion of a material that will not evaporate.

Non-Vulcanised Material: A material that retains its thermoplastic properties throughout its service life.

Nonwoven: Random arrangement of the reinforcement fibres of a scrim sheet or mat.

Nosing: Metal (or Fibreglass) flashing formed at a 90º angle and is installed around roof perimeters, curbs, platforms, etc. in order to protect the edge of the roofing system. Nosing should not be used in place of drip edge.

Below is an example of the difference between drip edge and nosing. Though nosing is used commonly, the drip edge is better because it help keep run-off away from the fascia.

Although these pages are checked regularly and every care is taken with the information within. Delston can not accept any responsibility or liability for information or results displayed within due to third party interference.

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