"Working Hard To Put a Roof Over Your Head"
Alligatoring- Surface cracking due to oxidation and shrinkage
stresses, which shows as repetitive mound of an asphalt surface, resembling
the hide of an alligator.
Application Temperature- The temperature of the hot bitumen when
applied on the roof which should be not more than approximately 50°
F less than the correct kettle temperature.
Asphalt- 1.A dark brown to black bituminous substance that is
found in natural beds and is also obtained as a residue in petroleum or
coal-tar refining that consists chiefly of hydrocarbons. 2. An asphaltic
composition used for pavements and as a waterproof cement. Canadian
roofing asphalts are generally from the heavy end of petroleum distillation
and can be obtained in a great range of viscosities and softening points.
Asphalt Primer- A solution of asphalt in petroleum solvent, used
to prepare concrete roof decks for the application of hot asphalt to the
Attic- The open space between the underside of the roof sheathing
and the upper side of the ceiling directly below the roof.
Base Sheet- A heavy sheet of felt sometimes used as the first ply
in built-up roofing.
Base Flashing- 1.That portion of the flashing which 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. 2. 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. The simple principle is to turn the membrane up along
the vertical surface, so that the roofing forms a large watertight tray, the
only outlets from which are the roof drains to dispose of the water.
Bituminous felts are usually used for a bituminous roofing.
Bitumen- Bitumen's 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 more serious blisters
are structural blisters. They occur in many forms of deformation and
are not confined to the exposed surface. They are caused mainly by the
expansion of trapped air and water-vapor or moisture or other gases. Air and
moisture trapped within the construction tend to expand during a rise in air
temperature or from the heat of the sun, and this expansion causes the plies
of the roofing to separate and bulge the roof surface in a balloon effect.
The blisters are spongy to the touch, and may occur between any of the
layers of roofing felt, or between membrane and deck, or membrane and
Block Method- The method of applying shingles in vertical rows
from eave to peak rather than in horizontal rows from rake to rake.
This method makes shading more noticeable and can lead to improper
fastening. It is not a recommended method. Also called straight
Blueberry- A term sometimes used to describe weather blisters.
These are small surface blisters, which can be seen in large numbers over
the entire roof area, more predominant during warm weather where roofs are
exposed directly to the sun, and which are a result of natural weathering of
the surface bitumen. Volatiles and water vapor in the bitumen tend to
be driven off by heat, and when the gases are trapped they form small
blisters. This type of blistering usually does not cause any failure
during the normal life of the roof. Also sometimes called pimpling,
pin blistering and bitumen bubbling.
Bond- Adherence between plies of felt, or between felts and other
elements of roof systems, which use bitumen or other materials as the
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- A built-up roofing consists of plies or layers
of roofing felt bonded together on site with hot bitumen. A protective
surface coating of gravel or slag is sometimes embedded in a heavy top
coating of hot bitumen. It is laid down to conform to the roof deck,
and to protect all angles formed by the roof deck with projecting surfaces,
and forms a single unit flexible waterproofed membrane fastened to the deck
by cementing and nailing. The simple principle on flat roofs is to
turn the membrane up to form a skirting or base flashing on the vertical
surfaces making a large watertight tray. The only outlets from this
tray are the roof drains to dispose of water.
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. They may be a
beveled strip of wood or insulation and in some cases cement grout or
Cantilever- A self supporting projection without external bracing
in which a beam or series of beams is supported by a downward force behind a
Cap Flashing- That portion of the 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- Fill in a joint with mastic or cement.
Cement Asphaltic Plastic- A mixture of asphalt, solvent and
mineral stabilizer used for example to adhere flashings or to fill pan
Clawing- The downward curving of the butt portion of the shingle.
This creates a hump along the leading edge and a widening of the cut-out.
The bulge thus created is susceptible to substantial damage by wind action,
hail and ice. Clawing is part of the normal aging process of shingles
and is a sign of long service.
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.
Collar- A metal cap flashing around a vent pipe projecting above a
Concealed Nailing- Application of roll roofing in such a manner as
to conceal or cover all nail heads used to fasten the roofing to nailable
decks. Also referred to as blind nailing.
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 rain water 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.
Cornice-Projection at the top of a wall. Term applied to a
construction under the eaves where the roof and side walls meet. The top
course, or courses of a wall when treated as a projecting crowning member.
Counter Flashing- Strips of metal, roofing, or fabric inserted and
securely anchored to the reglet or attached to a vertical surface above the
plane of the roof and turned down over the face flashing to protect the base
Course- Row of shingles that can run horizontally, diagonally or
vertically and sometimes termed the run of the shingle.
Cracking- After long exposure, a fissure or fissure pattern
appearing on the shingle or roofing due to weathering of the asphalt.
Crazing- Surface deterioration of a shingle by the formation of a
pattern of fine hairline cracks.
Cutout- The slot between shingle tabs to create the distinctive 2
or 3 tab appearance.
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, and at expansion joints in the roof deck.
Cut Off- A piece of roofing membrane consisting of one or more
layers of felt used to seal the edges of insulation at the end of a day's
work, or to separate the insulation into multiple areas so that, in case of
a roof leak, any damage would be isolated to the cut-off section surrounding
or adjacent to the leak.
Cut Back- A solution of bitumen in a volatile solvent. Cut
backs are used as primers, cold application cementing agents, and damp
Dead Load- The total weight of all installed materials and the
constant weight of a roof used to compute the strength of all supporting
Deck- The structure of the roof to the top surface of which a roof
covering system is applied. Some forty or more roof deck types are currently
in use in the construction industry.
Dormer- A separate smaller roofed structure that projects from a
sloping roof to provide more space below the roof and to accommodate a
Double Pour- The application of the top coating of bitumen and the
gravel surfacing of a built-up roofing in two separate applications, used on
dead level roofs, particularly when the roof is designed for flooding with
water. This is accomplished by embedding a quantity of gravel in a
first top pour of bitumen and later repeating the operation with additional
gravel embedded in a second pour of bitumen.
Downspout- A pipe for conveying rain water from a roof gutter to a
drain, or from a roof drain to a storm drain.
Drip Edge- A modified L-shaped flashing used along the eaves and
rakes. The drip edge directs runoff water into the gutters of air and
away from the fascia.
Eave- The horizontal overhang that extends outward and is not
directly over the exterior walls or the building's interior.
Eaves Trough- A gutter at the eaves of a roof for carrying off
rain water. It may be of wood or metal attached to the eaves, or a
built-in part of the eaves design usually lined with metal.
Ell- An extension of a building at right angles to its length.
Emulsified Asphalt- Straight run asphalt liquefied by clay
emulsifiers and water. Finely divided dust-like particles of asphalt
are kept in suspension in a cold but unsolidified state. Cementing
action by solidification takes place when the water in the emulsion
evaporates. Asphalt dispersed in water.
End Lap- The amount of overlap at the end of a ply on the
application of roll roofing felts for built-up roofing.
Expansion Joint- A planned, controlled joint placed between two
roof surfaces or between two sections of a built-up roof. The
expansion joint allows the roof to expand without physical damage to the
roof or the building.
Exposure- That portion of a shingle that is exposed to the
weather. Exposure is usually measured from the butt of one shingle to
the butt of the next overlaying shingles.
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. Fascia is either one by or two by lumber. The
gutter system is usually nailed to the fascia.
Felt- A very general term used to describe roll roofing materials,
consisting of a mat of organic or inorganic fibers unsaturated, saturated,
or saturated and coated with asphalt or coal-tar pitch.
Felt, Asbestos- Felt- Made from asbestos fibers, impregnated or
impregnated and coated with asphalt.
Felt, Asphalt Saturated- Any type of felt that has been
impregnated or saturated with asphalt. Sometimes referred to as merely
asphalt felt, which can also mean felt impregnated and coated with asphalt.
Felt, Coated- Bitumen- Saturated felt that has been coated on one
or both sides with bitumen by further processing. Coated felt may be
used as base sheet, in some types of built-up roofing, and with mineral
surfacing added as cap sheets and shingles.
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 for use in built-up roofing applications the glass fiber mat is
impregnated with asphalt.
Felt, No. 15- Asphalt or coal-tar saturated felt weighing
approximately 15 pounds per 100 square feet.
Felt, Perforated- Asphalt saturated felt perforated with small
holes, which allow trapped air to escape during laying, and bitumen to enter
to form a well-bonded membrane.
Felt, Rag- A type of heavy paper made principally from wood fiber,
wood flour, waste paper and a small percentage of rag. It was formerly
made principally of rag when first used in the manufacture of roofing
materials. Rag felt is saturated or saturated and coated with bitumen
to produce a variety of roofing felts, and prepared roofing.
Felt, Tar Saturated- Felt impregnated or saturated with coal-tar
Fill- Lightweight concrete placed on a level roof deck in varying
thickness' to build slopes to the roof drains, also referred to as screeding.
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
Fire-resistant- Material that is resistant to catching on fire
when exposed to open flame or flaming ashes.
Fishmouthing- 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.
At the end of the exposure, the shingle will be perfectly flat. Fishmouthing is often the result of moisture absorption followed by moisture
evacuation in the shingle.
Flashing, Eaves- Treatment of the edge of a roof with felt and/or
Flashing Block- A specially designed masonry block having a slot
or opening into which the top edge of the roof flashing can be inserted and
anchored. Also known as raggle block.
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.
Gable- The triangular end of an exterior wall from the level of
the eaves to the ridge of a double sloped roof.
Gambrel Roof- A type of roof which has its slope broken by an
obtuse angle, so that the lower slope is steeper than the upper slope. A
double sloped roof having two pitches.
Glaze Coat- A mopping of bitumen on exposed felts to protect them
from the weather pending completion of the job.
Gravel Stop- A gravel guard used at the rakes and eaves of a
built-up gravel coated roof.
Gutter- Trough at the eaves of a roof to convey rain water from
the roof to a downspout.
Header- The beam into which the common joists are fitted when
framing around a roof opening. The headers are placed so as to fit
between two long beams or trimmers to support the joist ends.
Headlap- The overlapping of shingles or roofing felt at their top
edge. Roofing felt should be headlapped by a minimum of 2 in.
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. Also called a cottage roof.
Horizontal Application- The application of roll roofing parallel
to the eaves.
Ice Dam- A build-up of ice at the eaves drainage area or in the
valley of a sloping roof. An ice dam is very harmful since it prevents
melting snow or rain water from exiting the roof, and the water backs up
under the shingles instead.
Jack- A flanged metal sleeve used as part of the flashing around
small items that penetrate a roof.
Kettle Temperature- The temperature to which bitumen is heated in
the kettle. The maximum recommended kettle temperature varies with the
type of bitumen, but generally must never be greater than 400°
for coal tar pitch and 450° for asphalt.
Lap Cement- A cut back asphalt used for
cementing the laps of roll roofing.
Lean-to-Roof- The sloping roof of a room
having its rafters or supports pitched against and leaning on the adjoining
wall of a building.
Live Load- The total weight of all installed
equipment and materials and all variable weight (such as snow, ice and
people) that will move across a surface. Used to compound the strength
of all supporting framing members.
Lock Shingles- Designed with a mechanical
locking feature to provide effective wind resistance.
Membrane- A saturated cotton or burlap fabric
used for certain built-up roofing applications. Also used to describe the
combination of felts and layers of bitumen forming a single flexible unit
and waterproofing system of a built-up roof covering.
Mill Deck- A type of wood roof deck
constructed from wood planks placed on edge vertically, and spiked or nailed
Mopping- A layer of hot bitumen mopped
between layers of roofing felt. Also the act of spreading molten
Mopping, Full- The application of bitumen by
mopping in such a manner that the surface being mopped is entirely coated
with a reasonably uniform coating.
Mopping, Spot- Application of bitumen by
mopping in spots, during the placing of certain portions of some built-up
roofing systems, Staggered, roughly circular spots of bitumen in a fairly
regular pattern to secure felts to certain types of roof decks.
Mopping, Strip-The application of bitumen by
mopping in a strip pattern. On certain types of pre-cast slab decks when
mopping is kept back from the joints it is referred to as strip mopping.
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 the attachment of flashing. On slopes in
excess of 3 inches to the foot on non-nailable decks it is sometimes
necessary to embed nailing strips in the deck to provide for anchoring of
the roof to the deck to prevent sliding. Also simply called nailers.
Open Valley- A valley where the flashing is
exposed to the weather.
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.
Parapet- A low wall along the edge of and
surrounding a roof deck. It is generally an extension of exterior building
walls and fire walls that usually extend about a meter or less above the
Penetration- A measure of the viscosity of a
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 any 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 felts, and the flanges
stripped in with additional felts. Plastic roof cement is placed around the
metal support in the bottom of the pan, and it is then filled to the top
with bitumen. Also mastic pan.
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 of felt used to build up the membrane.
Ponding- The collecting of water in shallow
ponds on the top surface of roofing. Certain roofs are designed for the
ponding of water to a shallow depth over the whole surface of the roof deck,
to aid in summer cooling and as fire protection.
Pour Coat- The top coating of bitumen on a
built-up roof. The final pouring of hot bitumen into which the gravel or
slag surface dressing is embedded.
Primer- A cut back asphalt coating of thin
consistency used on concrete or metal preparatory to applying a built-up
Purlin- Boards laid from gable to gable on
which the common rafters sit.
Rafters- The lumber supports that make up the
roof structure. Usually 2"x12" lumber. The roof sheathing is nailed to the
Raggle or Raglet- A horizontal slot or
opening left in a parapet or other masonry wall into which the top edge of
flashing can be anchored. In unit masonry this is usually achieved by
inserting a 2" deep wood strip in a horizontal joint during construction and
later removing this strip. For concrete work it may be achieved by attaching
a wood strip or a patented metal form to the metal form to the concrete
forms before pouring.
Reglet- A groove in the vertical wall
adjacent to a roof surface, above the top of base flashing into which the
metal counterflashing is placed and rigidly held in place; it is either
formed in concrete or consists of a metal insert, or a "reglet block" of
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.
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
asphalt-coated on both sides, and finished on one side with natural or
synthetic colored mineral granules. Also called mineral surfaced.
Roll Roofing-Smooth Surfaced- A type of
roll-roofing which is asphalt-coated on both sides with either a smooth or
veined surface, finished with talc, mica, or other fine mineral particles.
Roll Roofing-Wide Selvage- Asphalt-coated
roll-roofing finished with natural or synthetic colored mineral granules for
only a part of its width, usually for 17 inches, and sometimes referred to
as 19 inch selvage. Sometimes also referred to as split sheet mineral
Roof Drain- The termination or fitting at the
roof of an interior drain or leader for draining rain water from nominally
flat roofs. The fitting itself usually consists of a base with or without a
sump, a clamp ring and gravel stop, and a basket strainer to prevent debris
clogging the drain. The base is sometimes fastened to the leader with an
expansion sleeved fitting. Some roofers dispense with the specially
engineered roof drains, and use instead a flanged copper pipe stripped into
the roofing felts with the end projecting loosely inside the leader.
Roof Insulation- Any medium or low density
material used as a 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 fills.
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 (if used) and roof deck as an entity.
Run- The horizontal distance between the face of a wall and the
ridge of the roof, being half the span for asymmetrical gable roof.
Sometimes, though incorrectly, used to denote the slope distance from the
eave to the ridge.
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 connected to internal drains are also sometimes
installed at roof and wall junctions.
Self-healing- A term used in reference 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 unsurfaced strip along a sheet or roll roofing which
forms the under portion at the lap in the application 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 and flexibility.
Sky Dome- Dome shaped plastic cover for a curved opening in a roof
to admit light to the interior.
Sky Light- Glazed opening in a roof to admit light.
Soffit- A board or sheet that extends from the fascia to the
buildings siding and hides the bottom of an overhang. Soffit can be made
from wood, vinyl plastic, sheet steel, aluminum, and other materials. Soffit
may or may not contain ventilation slots depending of the attic venting
Soil Stack- The main vertical pipe which receives waste matter
from all plumbing fixtures. The vent stack to the roof frequently is
incorrectly referred to as the soil stack.
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. Also whenever the roof
shingles must butt up against the wall or chimney and the shingles
transverse from the eaves to the ridge.
Tab- Weather exposure surface of a shingle between the cutouts.
Tabbing- Method of applying high strength adhesives to shingles
for wind resistance.
Tear-off- Removal of existing roofing materials down to the roof
Trimmers- A beam that receives the end of a header.
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
Tuck Pointing- Mason term used for describing the act of placing
mortar into a joint with the use of a pointed trowel. Usually done during a
repair of an item like a chimney.
Under-driven- Term used to describe a fastener not fully driven
flush to the shingles surface.
Underlayments- Asphalt based rolled materials designed to be
installed under main roofing material, to serve as added protection.
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. Vinyl, plastic, aluminum foil, Kraft paper, asphalt
felt, asbestos felt and a laminated combination of these materials are
considered vapor barrier materials.
Vent Sleeves- Sheet metal flanged collars placed around vent pipes
for the purpose of sealing off the roofing around the vent pipe openings.
Vent- An outlet for air; vent pipe in a plumbing system; a
Vent Pipe or Vent- A vertical pipe providing an escape for foul
gases 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
Ventilators- Devices installed on the roof for the purpose of
ventilating the interior of the building. Frequently combined with
motorized fan equipment mounted on the roof, to provide positive air flow.
Viscosity- The internal frictional resistance offered by a fluid
to change of shape or to the relative motion or flow of its parts. Viscous
materials are glutinous, adhesive and sticky.
Water Vapor- Moisture existing as a gas in air. Warm air can hold
more water vapor than cold air. Water vapor in the air creates a pressure
much like any other gas. Cold air has a relatively low vapor pressure, but
warm air with larger amounts of water vapor has a greater pressure. The
difference in pressures cause the vapor to do strange things such as
penetrating building materials in the direction from high to low vapor
Wrinkle- A slight ridge caused by folding, rumpling or creasing .
In roofing usually refers to the common "wrinkle" pattern that forms over
the joints of insulation in insulated roof systems. See also buckling.
BACK TO TOP
Send mail to
email@example.com with questions
or comments about this web site.
Last modified: 03/28/2007