-A-

Alligatoring - Surface cracking due to oxidation and shrinkage stresses, which shows as mounding of an asphalt surface, resembling the hide of an alligator.

Asphalt - a. A dark brown to black substance found in natural beds and is also obtained as a residue in petroleum or coal tar refining that consists chiefly of hydrocarbons. b. Ansphaltic composition used for pavements and as a waterproof cement.

Attic - The open space between the underside of the roof sheathing and the upper side of the ceiling directly below the roof.

-B-

Base Sheet - A heavy sheet of felt sometimes used as the first ply in built-up roofing.

Base Flashing - a. That portion of the flashing that is attached to or rests on the roof deck to direct the flow of water on the roof, or to seal against the roof deck. b. A material applied to the base of a wall extending above a roof, as a protection for the junction of the wall, and the roof. 

Bitumen - Bitumens are mixtures of hydrocarbons of natural or pyrogeneous origin; or combinations of both, frequently accompanied by their non-metallic derivatives, which may be gaseous, liquid, or solid, and which are completely soluble in carbon disulfide.  In the roofing industry the word covers both asphalt and coal tar pitch.

Blind Nailing - Shingles nailed in such a location that when the next shingle is applied, the nails of the first shingle do not show.

Blisters (structural) - The more evident and serious blisters are structural blisters.  They are caused by the expansion of trapped air and water vapor or other gases.  Air and moisture trapped within the construction tend to expand during a rise in air temperature of from the heat of the sun.  This expansion causes the plies of the roofing to seperate and bulge the roof surface in a balloon effect.

Block Method - Method of applying shingles in vertical rows from eave to peak instead of horizaontal rows.  This method makes shading more noticeable and can lead to improper fastening.  Also called straighth up method.

Bond - Adherence between elements of the roof system.

Breather - A type of roof vent consisting of a hooded flanged pipe 2" to 8" in diameter, penetrating the roofing membrane to allow escape of moisture from insulation.

Buckling - Warping or wrinkling of the roof membrane.

Built-up Roofing - layers of roofing felt bonded together on site.  A protective surface coating of gravel or slag is sometimes embedded in a heavy top coating of hot bitumen. 

-C-

Cant Strip - A beveled support used at the intersection of the roof deck with vertical surfaces so that bends in the roofing membrane to form base flashings can be made without breaking the felts. 

Cap Flashing - Portion of flashing built into a vertical surface to prevent the flow of water behind the base flashing.  The cap flashing overlaps and caps off the top of the base flashing.

Caulk - Used to fill in joints.

Cement Asphaltic Plastic - A mixture of asphalt, solvent and mineral stabilizer used to adhere flashings or to fill pan flashings.

Closed Valley - A valley where the flashing is covered by shingles.

Coal Tar Pitch - A bituminous material produced by distilling crude tar residue derived from the cooking of coal.  It is used as the waterproofing material for tar and gravel built-up roofing.

Concealed Nailing - Application of roll roofing in such a manner as to conceal or cover all nail heads used to fasten the roofing to nail able decks.

Condensation - The change from water vapor to liquid water, resulting from a drop in temperature of an air vapor mixture.

Conductor - A pipe for conveying rainwater from a roof gutter to a drain or from a roof drain to a storm drain.

Coping - The cap or highest covering course of a wall, usually overhanging the wall and having a sloping top to carry off water.

Counter Flashing - Strips of metal, roofing, or fabric inserted and securely anchored to the regle or attached to a vertical surface above the plane of the roof and turned down over the face flashing to protect the base flashing.

Course - Row of shingles that can run horizontally, diagonally or vertically.

Cracking - After long exposure, a fissure or fissure pattern appearing on the shingle of roofing due to weathering of the asphalt.

Curb - A wall of wood or masonry built above the level of the roof, surrounding a roof opening such as for installation of roof fans or other equipment.

-D-

Dead Load - The total weight of all installed materials and the constant weight of a roof used to compute the strength of all supporting framing members.

Deck - The top surface of which a roof system in applied. 

Dormer - A seperate smaller roofed structure that projects from a sloping roof to provide more space below the roof anf to accommodate a vertical window.

Downspout -  A pipe conveying rainwater from a roof gutter to a drain.

Drip Edge - A modified L-shaped flashing used along the eaves and rakes.  The drip edge directs runoff water into the gutters and away from the fascia.

-E-

Eave - The horizontal roof overhang that extends outward and is not directly over the exterior walls or the buildings interior.

Elk - Shingle manufacturer based out of Texas, provides elegant and innovative shingles.

Ell - An extension of a building at right angles to its length.

End Lap - The amount of overlap at the end of a ply on the application of roll roofing.

Expansion Joint - A planned, controlled joint placed between two roof surfaces or between two sections of a built-up roof.  Expansion joints allow roofs to expand without causing harm to building.

Exposure -  Portion of shingle that is exposed to the weather.

-F-

Face Nailing - Nailing with the nails placed in the exposed area or face of the shingle.

Fascia - A wood trim board used to hide the cut ends of the roof's rafters and sheathing. The gutter system is usually nailed to the fascia.

Fastening Tab - Part of Duro-Last roofing system where membrane is mechanically attached to the deck.

Felt - A very general term used to describe roll roofing materials, consisting of a mat of organic or inorganic fibers.

Felt (glass) - A non-woven mat of flexible glass fiber, formed by spreading fibrous material over a screen and pressing it together to form a sheet.

Felt (15 & 30) - Asphalt or coal tar saturated felt weighing approximately 15 or 30 pounds per 100 square feet.

Fire Wall - Any wall built for the purpose of restricting the spread of fire in a building.  Such walls of solid masonry or concrete usually divide a building from the foundations to about a meter above the roof.

Fire-Resistant - Material that is resistant to catching on fire.

Fish Mouthing - The raising of a portion of the butt edge (lower edge) of a shingle.  This curved short section tapers back into the shingle.  Usually, only the front part of the shingle is affected.  Often the reslut of moisture absorption followed by moisture evacuation in the shingle.

Flashing (eaves) - Treatment of the edge of a roof with metal.

Flashing - Metal strips used to form a watertight seal between the items butted up against the shingles.  Flashing is used along walls, chimneys and dormers. Metal is usually 28 gauge galvanized sheet metal, but may be lead, copper, tin or aluminum.

-G-

Gable - The triangular end of an exterior wall from the level of the eaves to the ridge of a double-sloped roof.

GAF - Shingle manufacturer based in New Jersey.  Have been in business since the l886, GAF has a wide variety of shingle styles and colors.

Gambrel Roof - A type of roof which has its slope broken by an obtuse angle, so that the lower slope is steeper that the upper slope.  A double-sloped roof having two pitches.

Grande - Elk's newest shingle offering.  More than40% bigger than standard shingles.  Has a 90 mph wind warranty.

Gravel Stop - A gravel guard used at the rakes and eaves of a built-up gravel coated roof.

Gutter - Through at the eaves of a roof to convey rainwater from the roof to downspout.

-H-

Header - The beam into which the common joists are fitted when framing around a roof opening. 

Head Lap - The overlapping of shingles or roofing felt at their top edge.

Heat Welding - A hot air process where two seperate pieces of material are welded together.

Hip Roof - A roof, which rises by inclined planes from all four sides of a building.  The line where two adjacent sloping sides of a roof meet is called the hip. 

-I-

-J-

-K-

-L-

Lap Cement - A cut back asphalt used for cementing the laps of roll roofing.

Live Load - The total weight of all installed equipment and materials and all variable weight that will move across a surface. 

-M-

Membrane - A saturated cotton or burlap fabric used for certain built-up roofing applications.  Also a waterproofing system or roof covering.

-N-

Nailing Strips - Strips of wood placed at the eaves of all types of roof decks except wood, and at the tops of masonry expansion or ventilation curbs for attaching the flashing.  Also called nailers.

-O-

Open Valley - A valley where the flashing is exposed to the weather.  (NOT A GOOD PRACTICE)

Overhang - That portion of roofing extending beyond the deck.  As related to the roof structure, that part of the roof structure which extends beyond the exterior walls of a building.

-P-

Parapet - A low wall along the edge of and surrounding a roof deck.  It is generally an extension of exterior building walls and above firewalls that usually extend about a meter or less above the roof.

Penetration - A measure of the viscosity of a bitumen.

Pitch - Height from the joist to ridge divided by rafter length, which translates to rise in inches per horizontal foot or ratio of pitch.  Ratio is an portion up to full pitch (24" in 12").

Pitch Pan or Pocket - Usually a rectangular flanged metal collar placed around metal supports that project above a roof deck.  The pitch pan is placed on top of the roofing underlayment. 

Ply - A single layer or thickness of roofing material.  Built-up roofs are described as three, four ply, etc., according to the number of layers used to build up the membrane.

Polyglass - Maker of self-adhered underlayments.  Have a wide array of products for every type of roof system.

Polyglass TU Plus - Self-adhered Modified Rubber Tile and Metal underlayment.  This membrane is glass fiber reinforced, with a high strength polyester fiber fabric on the upper surface.

Polyglass UDL - family of products are high strength, polyolefinic, multi-laminate roof covering underlayments manufactured using highly durable structures and formulated with anti-skid protection on the top surface to provide significantly enhanced slip resistance, even during wet and slippery conditions.

Ponding - The collecting of water in shallow ponds on the top surface of roofing.  Certain roofs are designed for the ponding water to a shallow depth over the whole surface of the roof deck, to aid in summer cooling.  Many flat roof systems void their warranties if ponding water sits on the deck for more than 48hrs.

Primer - A cut back asphalt coating of thin consistency used on concrete or metal preparatory to applying a built-up roof.

Purlin - Boards laid from gable to gable on which the common rafters sit.

-Q-

-R-

Rafters - The lumber supports that make up the roof structure.  Usually 2" x 12" lumber.  The roof sheathing is nailed to the rafters.

Reglet - A groove in the vertical wall adjacent to a roof surface, above the top of base flashing into which the metal counter flashing is placed and rigidly held in place; it is either formed in concrete or consists of a metal insert.

Ridge - The horizontal line where two opposite sloping sides of a roof join at the highest point of the roof, hip, or dormer.  On double sloped gable roofs sometimes called the comb.

Ridge Cap - Formed shingles, shake or tile used to cover the ridge of a building.  Make sure that specially designed cap products are used.  Many roofers will use materials not made for this purpose.

Roll Roofing - Any roofing material, which comes from the dealer in rolls.  More specifically it applies to mineral surfaced asphalt, or composition roofing.

Roll Roofing (granule surfaced) - Roll roofing finished on one side with colored granules.

Roll Roofing (smooth surfaced) - Roll roofing which is coated on both sides with either a smooth or veined surface.

Roof Drain - The termination or fitting at the roof of an interior drain or leader for draining rainwater from normally flat roofs.

Roof Insulation - Any medium or low density material used as part of the roofing system to reduce heat loss through the roof.  A variety of insulation materials are being used including wood fibers, glass fibers, cork, plastics and poured lightweight.

Roof Span - Distance from outer wall to opposing outer wall of a building covered with a roof.

Roofing System - The waterproof roof covering, roof insulation, vapor barrier and roof deck as an entity.

Run - The horizontal distance between the face of a wall and the ridge of the roof.

-S-

Scrim - A key component of the Duro-Last roofing system.  The scrim is weft inserted creating a grid-like appearance.  If the Duro-Last membrane is ever punctured the scrim tightens up preventing the tear from gaining in size.

Scupper - An outlet in the wall of a building or a parapet wall for drainage of overflow water from a floor or roof directly to the outside.  Special scupper drains connectd to internal drains are also sometimes installed at roof and wall junctions.

Self-Healing - A term used in refrence to bitumen which melts with the heat from the sun's rays, and seals over cracks that earlier formed in the bitumen from other causes. 

Selvage - The un-surfaced strip along a sheet or roll roofing which forms the under portion at the lap in the applicatin of the roof covering.

Side Lap - The horizontal distance one shingle overlaps adjacent shingle in the same course; also the horizontal distance one sheet of roofing overlaps adjacent sheet.

Single Coverage - Method of applying roof shingles to provide only one complete layer of roof protection.  Many special shingles for re-roofing are designed for single coverage for reasons of economy.

Sky Light - Glass opening in roof to admit light.

Slateline - GAF shingle made to mimic conventional slate roofing, a highly attractive shingle with a pronounced shadow effect.

Soffit - A board or sheet that extends from the fascia to the buildings siding and hides the bottom of an overhang.  Soffit may or may not contain ventilation slots depending on the attic venting system used.

Starter Course - The first course of shingles installed on a roof, starting at the lower left edge of the eave.

Step Flashing - Metal shingles or plates used in a stair-step pattern under regular shingles.  Step flashing is the recommended flashing whenever a wall or chimney is above the roof line.

-T-

Tab - Weather exposure surface of a shingle between the cutouts.

Thermoplastic - Type of single-ply membrane that can be heat welded and includes a re-inforcement layer of polyester (scrim), which provides increased strength.  Thermoplastic membranes are light in color and will usually result in energy savings.

Titanium Dioxide - Used in thermo-plastic roofing membranes to reflect UV rays and to protect the polymers in the roofing material.

Truss - A combination of members such as beams, bars and ties, usually arranged in triangular units to form a rigid framework for supporting loads over relatively long spans as in wide span roof construction.

-U-

-V-

Valley - The horizontal line formed along the depressed angle at the bottom of two inclined roof surfaces.

Vapor Barrier - A material that prevents the passage of water or water vapor through it.

Velux - One of the world leaders in skylight manufacturing.  Uses all glass skylights instead of plastic bubbles that are common in the industry today.

Vent - An outlet for air; vent pipe in a plumbing system; a ventilating duct.

Vent Pipe - A vertical pipe providing an escape for foul gasses from a sanitary fixture.  For a number of fixtures the vent pipes lead into a larger vertical pipe to the outside through the roof called a vent stack.

-W-

Water Vapor - Moisture as a gas in air.  Warm air can hold more water vapor than cold air.  Water vapors in the air crates a pressure much like any other gas.  Cold air has a relatively low vapor pressure.

Wrinkle - A slight ridge caused by folding, rumpling or creasing.  In roofing usually refers to the common wrinkle pattern that forms over the joints or insulation.

-X-

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