Roofing Foreman key terms

The vertical rise of a roof surface measured over a horizontal run, usually stated as a ratio such as 4:12. It determines drainage performance and which underlayment and flashing methods are permitted.

A way of expressing roof incline as a fraction of span, historically written as rise over total span rather than over run. Crews often use the word loosely for slope, so foremen should confirm which measure a drawing intends.

A roof plane with a slope generally at or below 3:12, requiring continuous membrane or built-up waterproofing rather than relying on shingle overlap. Drainage design and ponding checks are critical on these surfaces.

A roof plane with a slope generally above 3:12, where water sheds quickly and layered roof coverings such as shingles or tiles are common. Slope governs underlayment requirements and fall-protection planning.

A sheet material installed over roof decking beneath the finished covering to provide a secondary moisture barrier. Product type and overlap depend on slope, climate, and whether ice damming is a concern.

A self-adhering waterproof membrane applied along eaves, valleys, and other vulnerable areas to stop water backed up by ice dams from entering the deck. Building codes specify where and how far it must extend.

A ridge of ice forming at the eave when melted snow refreezes, trapping water that can back up under the roof covering. Prevention relies on attic insulation, ventilation, and eave membrane placement.

The structural surface that supports underlayment and roof covering, commonly wood sheathing, plank, or concrete. Its condition, fastener holding, and flatness directly affect the installed assembly's performance.

Panels or boards fastened over rafters or trusses to form the nailable base for roofing. Gaps, delamination, and thin spots must be corrected before covering is applied.

A metal flashing at roof edges that directs water away from fascia and sheathing and helps shed water clear of the wall. It is installed under underlayment at eaves and over it at rakes.

Metal or membrane components that seal roof intersections and penetrations against water entry, including valleys, walls, chimneys, and vents. Correct layering and overlap direction determine whether flashing actually sheds water.

Small L-shaped metal pieces woven into each course of sidewall siding and roofing to shed water at a wall-roof intersection. Pieces must be lapped in the direction of water flow and never face-nailed through the exposed leg.

Metal embedded in or attached to a wall or masonry above the roof surface that overlaps base flashing to keep water from getting behind it. The lap must remain open at the bottom to allow drainage.

The internal intersection where two roof planes meet and concentrate runoff. Valley lining method, width, and material depend on slope and covering type, and errors here are a leading cause of leaks.

The lower edge of a roof plane that overhangs the wall, where water leaves the roof and where ice damming typically begins. Eave details control ventilation intake and edge flashing.

The inclined edge of a gable roof running from eave to ridge. Rake edges need proper edge metal and underlayment termination to resist wind-driven rain.

The triangular wall section at the end of a pitched roof, bounded by two rakes and closed at the ridge. Gable ends are exposed to wind uplift and require careful sheathing and flashing details.

The highest horizontal line where opposing roof planes meet. Ridge venting and ridge cap installation affect attic ventilation and resistance to wind and water at the roof's peak.

An external roof intersection sloping downward from the ridge, forming a convex edge rather than a valley. Hip and ridge cap coverage must be lapped and fastened to resist wind uplift.

The balanced intake and exhaust of air through the roof assembly to control attic heat and moisture. Proper venting reduces ice damming, condensation, and premature shingle deterioration.

A material that limits moisture vapor movement into the roof assembly, placed according to climate and assembly design. Misplacement can trap moisture and cause deck rot or condensation.

Water that forms when warm moist air contacts a colder surface inside the roof assembly. It can saturate insulation and rot decking if ventilation and vapor control are inadequate.

Standing water remaining on a low-slope roof for more than a short period after rain, indicating insufficient slope or deflection. Persistent ponding accelerates membrane aging and can overload structure.

A fitting that carries water from a low-slope roof surface into the building's drainage system. Strainers, clamping rings, and sump details must be installed correctly to prevent clogging and leaks.

An opening through a parapet wall that lets roof water drain to the exterior. Scupper placement and flashing affect ponding depth and overflow performance on low-slope roofs.

A low wall extending above the roof surface, typically at the perimeter. Parapets create wall-flashing conditions and can trap water, so base and counterflashing details require close attention.

Rigid insulation cut in varying thicknesses and laid to create slope toward drains on a flat structural deck. It improves drainage and reduces ponding without altering the structure.

A large-sheet roofing material such as EPDM, TPO, or PVC installed on low-slope roofs. Seams, attachment method, and flashing compatibility determine its weathertightness and wind resistance.

The joined edge where two single-ply sheets overlap and are welded, taped, or adhered. Seam strength and continuity are tested because seam failure is a primary source of low-slope leaks.

A physical check in which a blunt tool is run along a finished membrane seam to find unsealed openings. It is a quality-control step performed before the roof is closed out.

The method and pattern of fasteners, adhesives, or ballast securing a roof assembly to the structure. Attachment design must resist calculated wind uplift pressures for the building's location and height.

Upward pressure created by wind flowing over a roof, strongest at corners and edges. Roof assemblies must be attached and detailed to resist these forces without lifting or peeling.

The resistance of a nail or screw to being withdrawn from the deck under load. It depends on fastener type, embedment, and deck material, and underpins wind-uplift calculations.

A temporary bracket or staging platform secured over the roof surface to support workers and materials on steep slopes. Correct placement protects the covering and provides stable footing.

Systems and practices preventing workers from falling from roof edges, openings, or steep surfaces, including guardrails, personal fall arrest, and warning lines. A written plan and trained workers are required before roof work begins.

A prefabricated structural frame of chords and webs that supports the roof deck and transfers loads to walls. Trusses must not be cut or altered without engineering approval.

A wall that rises above or meets a sloping roof plane, creating a flashing transition. The intersection requires base and counterflashing lapped so water cannot enter behind the wall covering.