Roofing Glossary

A roof covering built with a reinforcing mat, asphalt, and mineral surfacing. Product construction, profile, installation instructions, and warranty terms vary by manufacturer and product line.

A designed combination of intake and exhaust openings for air movement through an attic or roof assembly. Requirements depend on the building, roof system, code, and manufacturer instructions.

A rubber or metal flashing component that seals around pipes and vents where they penetrate the roof. Also called a pipe boot or plumbing vent boot. Boots deteriorate over time and are common leak sources.

A low-slope roof system made from multiple layers of bitumen and reinforcing material, usually finished with aggregate, a coating, or a cap sheet.

A classification under the UL 2218 laboratory impact test. It is not a hail-proof guarantee. Verify the exact product listing and ask an insurer directly about eligibility or discounts.

Metal flashing installed into masonry or siding that overlaps step flashing to direct water away from walls. Essential where roofs meet vertical surfaces like chimneys and walls.

A peaked saddle constructed behind a chimney or other roof projection to divert water around it. Also called a saddle. Prevents water pooling and leaks behind chimneys.

The structural surface, often wood panels or boards, that supports the roof covering. Required material, span rating, thickness, condition, and attachment depend on the assembly and applicable requirements.

A structure projecting from a sloped roof, usually containing a window. Dormers add complexity to roofing and require careful flashing to prevent leaks.

Edge flashing used to direct water away from the roof edge and underlying components. Placement and requirements depend on the roof system, manufacturer instructions, and applicable code.

The horizontal edge of a roof that overhangs the exterior wall. Eaves protect walls from water and provide shade. Ice dams commonly form at eaves in cold climates.

Ethylene propylene diene monomer, a single-ply membrane used in low-slope roof assemblies. Products, colors, thicknesses, attachment methods, and seam details vary.

The vertical board along the roof edge where gutters are typically mounted. Fascia protects the roof edge and provides a finished appearance. Often damaged by ice dams or gutter problems.

Traditional asphalt-saturated underlayment installed under shingles. Being replaced by synthetic underlayments in many applications. Standard weights are 15-lb and 30-lb per 100 square feet.

Metal pieces installed to prevent water intrusion at joints, transitions, and penetrations in the roof system. Critical at valleys, chimneys, vents, walls, and skylights. Common materials include aluminum, galvanized steel, and copper.

The triangular portion of an exterior wall below the edges of two sloping roof planes.

Mineral surfacing embedded in asphalt shingles for color and surface protection. Loose or missing granules can have several causes and should be evaluated in context.

A channel installed along a roof edge to collect runoff and route it to downspouts. A seamless run reduces intermediate joints but still has outlets, corners, end caps, and other details that require installation and maintenance.

A property-specific finding that hail impact caused functional or physical change to a roof component. A nearby weather report or surface mark alone does not establish cause, scope, or coverage.

The external angle formed where two sloping roof planes meet. Hip roofs have hips instead of gables at the ends. Hip shingles are specialty shingles designed for this application.

Ice accumulation near a roof edge that can obstruct drainage and allow meltwater to back up. Contributing conditions and appropriate correction depend on the building and roof assembly.

A self-adhering membrane used in selected roof areas as part of a water-shedding assembly. Location and installation depend on applicable code, roof design, and manufacturer instructions.

A roof slope that requires materials and details approved for lower-slope drainage conditions. Exact slope limits depend on the selected system and applicable requirements.

Roof coverings or assemblies made from metal panels, shingles, or tiles. Metal type, coating, seam, fastening, substrate, impact performance, fire classification, and warranty vary by product.

A flat roofing material made from asphalt modified with rubber or plastic polymers. Applied in layers by torch, hot mop, or self-adhesive. Common on commercial and low-slope residential roofs.

An engineered wood panel made from oriented wood strands and adhesive. When used as roof sheathing, its span rating, thickness, exposure classification, condition, and installation must suit the assembly.

The angle of a roof expressed as a ratio of rise to run (e.g., 6:12 means 6 inches of rise per 12 inches of horizontal run). Affects drainage, material choices, and installation methods.

A layer of roofing material in a multi-layer system. Built-up roofs typically have 3-5 plies. The term also refers to the layers in composition shingles.

The inclined edge of a sloped roof over a gable. Rake edges require proper drip edge and may need special treatment to prevent wind-driven rain intrusion.

The horizontal line where two roof planes meet at the highest point. Ridge vents installed along this line provide excellent attic exhaust ventilation.

A continuous ventilation system installed along the roof ridge that allows hot air to escape from the attic. Works with soffit vents to create natural convection airflow.

A measure of resistance to heat flow. Required insulation values depend on location, building type, assembly, alteration scope, and the currently adopted energy code.

The boards or panels attached to roof rafters that provide a nailing surface for roofing materials. Typically plywood or OSB. Must be in good condition for proper roof installation.

The underside of the roof overhang. Vented soffits provide crucial intake ventilation for the attic. Damaged soffits can allow pests and moisture into the attic.

A roofing quantity equal to 100 square feet of roof surface. Order quantities also account for layout, waste, starter, ridge, and product packaging.

A metal roof-panel system with raised longitudinal seams. Seam design, clip or fastening method, panel profile, substrate, coating, and tested performance vary by system.

L-shaped metal pieces woven into shingles where the roof meets a vertical wall. Each piece overlaps the one below, directing water away from the wall junction.

The first course of shingles installed along the eave, designed to seal under the first full course of shingles. Provides wind resistance and prevents water intrusion at the edge.

Thermoplastic polyolefin, a single-ply membrane used in low-slope roof assemblies with heat-welded seams. Thickness, reinforcement, color, attachment, and warranty vary by product and system.

A layer installed between the roof deck and roof covering as part of the assembly. Material, laps, fastening, exposure limits, and use around transitions depend on the selected system.

The V-shaped intersection where two sloping roof planes meet. Valleys channel large amounts of water and require special flashing and underlayment to prevent leaks.

Intake and exhaust openings designed for air movement through an attic or roof assembly. Net-free area, balance, placement, and compatibility depend on the building and applicable requirements.

Manufacturer warranties and contractor workmanship warranties are different documents with different issuers, coverage, exclusions, terms, and claim procedures. Read the exact product and project documents before relying on a warranty statement.

A property-specific finding that wind caused change to a roof component, such as displacement, detachment, deformation, or opening. Cause should be distinguished from aging, installation, foot traffic, and other conditions.