At Chicago Skylights, NOTHING is more important to us than your satisfaction and long term pleasure with our skylights. We would like for our clients to understand the different parts and areas of their roof. This will give you a better understanding of how your skylight project will be completed, and make you feel more comfortable with the procedure.


Roofing & Skylight Terms Defined.

Acrylic: A synthetic plastic material containing derivatives of acrylic acid with great
thermoformability, usually used for domed skylights.

Asphalt: A bituminous waterproofing agent applied to roofing materials during manufacturing.

Back Surfacing: Fine mineral matter applied to the backside of shingles to keep them from sticking

Blisters: Bubbles that may appear on the surface of asphalt roofing after installation.

Built-up roof: A flat or low-sloped roof consisting of multiple layers of asphalt and ply sheets.

Cladding: An exterior skin applied to framing for aesthetic or protective purposes.

Concealed nail method: Application of rolled roofing in which all nails are driven into the underlying
course of roofing and covered by a cemented, overlapping course. Nails are not
exposed to the weather.

Condensation: The change of water from vapor to liquid when warm, moisture-laden air comes
in contact with a cold surface.

Condensation Gutter: A gutter for collecting and carrying off infiltrated water to exterior or to be evaporated.


Roofing & Skylight Terms Defined

Curb Mount:
A frame, usually wood and 2"x4", that allows a skylight to be mounted on top allowing
a greater height differential between roof deck and skylight. Used for flat or low sloped roofs.

Deck/sheathing: The surface, usually plywood or oriented strand board to which roofing materials are applied.

Dormer: A small structure projecting from a sloped roof, usually with a window.

Double Glazed: Any glazing consisting of 2 lites of glass separated by an air space.

Downspout: A pipe for draining water from roof gutters. Also called a leader.

Drip edge: An L-shaped strip (usually metal) installed along roof edges to allow water run off to drip
clear of the deck, eaves and siding.

Eave: The horizontal lower edge of a sloped roof.

Edging Strips: Boards nailed along eaves and rakes after cutting back existing wood shingles to provide
secure edges for re-roofing with asphalt shingles.

Fascia: A flat board, band or face located at a cornice's outer edge.

Felt/Underlayment: A sheet of asphalt-saturated material (often called tar paper) used a secondary layer
of protection for the roof deck.

Flashing: Pieces of metal or roll roofing used to prevent seepage of, and redirect water flow from entering into a
structure or projection in a roof such as skylights, chimneys, adjoining walls, dormers and valleys.

Gable: The upper portion of a sidewall that comes to a triangular point at the ridge of a sloping roof.

Granules: Ceramic-coated colored crushed rock that is applied to the exposed surface of asphalt roofing products.

Interlocking shingles: Individual shingles that mechanically fasten to each other to provide wind resistance.

Laminated Glass: A layer, usually of polyvinyl butyral (PVB), bonded between 2 glass lites to prevent shattering.

Lite: A single "pane" of glass. Lite is the preferred term over pane.

Low E: Low Emittance coating. a coating applied to glass that reduces the amount of heat transfer.

Louvers: Slatted devices installed in a gable or soffit (the underside of eaves) to ventilate the space below a roof deck
and equalize air temperature and moisture.

Oriented Strand Board (OSB): Roof deck panels (4 x 8 feet) made of narrow bits of wood, installed lengthwise
and crosswise in layers, and held together with a resin glue. OSB often is used as a
substitute for plywood sheets.

Overhang: That portion of the roof structure that extends beyond the exterior walls of a building.

Pitch: The degree of roof incline expressed as the ratio of the rise, in feet, to the span, in feet.

Purlin: In a skylight system, a structural framing member between rafters; generally at or near horizontal.

Rafters: The supporting framing to which a roof deck is attached.

Rake: The inclined edge of a roof over a wall.

Ridge: The top edge of two intersecting sloping roof surfaces.

Sheathing: The boards or sheet materials that are fastened to rafters to cover a house or building.

Soffit: The finished underside of the eaves.

Slope: Measured rise in inches. A roof with a 4:12 slope rises 4 inches for every foot of horizontal distance.

Tempered Glass: Glass that has been heated and quenched to provide extremely high strength.

Truss: Engineered components that supplement rafters in many newer homes and buildings. Trusses are designed
for specific applications and cannot be cut or altered.

U Factor: Measurement of how well a product prevents heat from being transmitted. Lower U Factor, the better.

Underlayment: A layer of asphalt saturated (sometimes referred to as tar paper) which is laid down on a bare deck
before shingles are installed to provide additional protection for the deck.

Valley: The angle formed at the intersection of two sloping roof surfaces.

Vapor retarder: A material designed to restrict the passage of water vapor through a roof
system or wall.

Vent:. Any device installed on the roof for the purpose of ventilating the underside of the roof deck.

Weep Hole: A hole placed in a framing member to allow infiltrated water to drain to the exterior of the structure.

Whether it's skylights in Chicago, skylights in Naperville, skylights in Tinley Park or skylights anywhere in the metro suburban area, Chicago Skylights is there !