21st Century Painting & Roofing

Roofing Glossary: A-M

Roofing Glossary: A-M

We talk a lot about roofing on this blog. We thought it was time to give you a little bit of a roofing glossary. We’re going to tackle terms in the A-M portion of the alphabet this week and next week, we’ll deal with N-Z.  We’ll try to keep it basic for you. We hope you enjoy the roofing glossary.


Abrasion resistance – the ability to resist being worn away by contact with another abrasive object that is also in motion. This refers to foot traffic, mechanical equipment, etc.

Absorption – a material’s ability to accept quantities of gases or liquids such as moisture.

Adhesion – a steady or firm attachment of materials to each other.

Aggregate – any granular material that’s used for surfacing a built-up roof system.

Application Rate – the average amount of material applied per unit area.

Attic – the open space above the ceiling that’s immediately under the roof deck of a steep-slope roof.


Ballast – a material that employs its mass and the force of gravity to hold single-ply roof membranes in place.

Beam – a primary member – it’s usually horizontal – subject to bending loads.

Bond – adhesive and cohesive forces that hold two roofing components together in direct contact.


Caulking – 1) a physical process of sealing a joint or juncture, 2) sealing and making the joints weather-tight. Filling in any seams or voids that are adjacent with a sealant.

Chimney – a prefabricated material made of stone, metal or wood that contains one or more flues. It projects through and above the roof.

Condensation – when water vapor or another gas converts to liquid as the temperature drops or atmospheric pressure rises.

Cohesion – molecular forces of attraction in which a material or materials are held together.


Deck – it’s a structural component of the roof of a building. It must be able to safely support the design dead and live loads which includes the weight of the roof.

Dew point temperature – the temperature at which air becomes saturated with water vapor. This is when relative humidity is at 100%.

Drain – An outlet that was used to collect and direct the flow of runoff from an area of the roof.

Durability – It explains the ability to withstand physical, chemical or environmental abuse.


Eave – the lower edge of a roof that slopes. It is that part of the roof which goes beyond the wall.

Elasticity – the property of a material that causes it to return to its original shape after being deformed in some way such as stretching or compression.

Erosion – 1) weathering, wearing away or degradation; 2) when a coating wears away by chalking or the abrasive action of certain substances.


Fading – when the initial coloring gets lightened for some reason.

Fireproofing – using materials to avoid the spread of fire if it should occur.

Flammability – characteristics of a material that relate to the ease of ignition and its ability to sustain combustion.

Flashing – Items used to weatherproof or seal a roof at locations where the roof covering is interrupted or terminated.

Freeze-thaw resistance – A material’s ability to resist cycles of freezing and thawing that could affect the material’s applications, appearance or performance.


Gauge – a measurement of metal thickness

Gutter – this describes a channeled component that’s installed along the downslope of the roof’s perimeter to take runoff water from the roof to the drainage system or downspouts.


Heat Flow – the amount of heat transferred to or from a system expressed in a unit of time.

Heat transfer – the transmission of thermal energy coming from a location of higher temperature and going to an area of lower temperature. Heat transfers can occur via conduction, convection or radiation.


Ignition temperature – this represents the lowest temperature at which combustion will occur spontaneously when specific conditions are present.

Impact resistance – a material’s resistance to fracture under sudden application of an exerted force.

Incline – a way to express the slope of a roof in percent or units of vertical rise per units of horizontal run.

Insulation – materials designed to reduce the flow of heat into or out of a building.


Joist – a configuration of small beams, timbers or metal arranged parallel to one another. A joist spans from wall to wall to support a ceiling or roof of a building.


k-value – the time rate at which heat flows through a unit area of a homogeneous material in a direction perpendicular to isothermal planes induced by a unit temperature gradient.


Laminate – to bring layers of material together with fusion. It’s also known as the process of joining layers of materials together by using adhesion.

Lap – a part of a roof, waterproofing or flashing that overlaps or covers any portion of an adjacent component.

Low-temperature flexibility – this is the ability of a material to resist cracking after it has been cooled to a low temperature and flexed.


Mastic – this is a thick, adhesive material that is used a cement of sorts to hold waterproofing membranes in place

Metal – any type of opaque, fusible, ductile and usually lustrous substances that are also good conductors of electricity and heat.

Meter – a unit of length measurement. 1 meter is equal to 39.37 inches.

Mil – a unit of measurement. A mil is equal to 0.001 inches. It’s often used to describe the thickness of a roof’s membrane.

Mold – a surface growth of fungus on damp or decaying matter.

Well, that’s it for now. Next week, we’ll focus on N-Z. Hopefully, this roofing glossary has clarified some roofing terms for you. If not, give us a call at 512-219-0342. We’re happy to help.