FGIA InstallationMasters key terms

The framed structural gap in a wall, sized larger than the window or door unit, into which the product is fitted and shimmed during installation.

The dimensions of the actual window or door frame, measured outside-to-outside, which must fit inside the rough opening with allowance for shimming and leveling.

A unit installed into an existing framed opening, typically after removing the old sash or full frame, without altering the structural wall opening.

A replacement method where the new unit fits inside the existing window frame and stops, leaving the original frame and exterior trim in place.

A replacement method where the entire old frame, sash, and often exterior trim are removed back to the rough opening before the new unit is installed.

A factory-made replacement unit designed to fit within an existing frame, usually with its own jamb liner and no nailing fin.

A projecting flange around a window or door frame that is fastened to the wall sheathing to anchor and seal the unit in new construction.

Layered weather-resistant material integrated with the wall assembly to direct water away from the opening and behind the exterior cladding.

Flashing installed above a window or door head to shed water over the unit and lap over the side flashing in shingle fashion.

A sloped, watertight pan or flashing detail at the bottom of an opening that collects and drains any water that reaches the sill.

The sheet or fluid-applied membrane on the wall behind cladding that blocks bulk water and must be lapped by opening flashing.

A common spun-bonded or woven sheet product used as a water-resistive barrier over sheathing before windows and cladding are installed.

The structural panel layer, such as plywood or oriented strand board, fastened over wall framing to which nailing fins and flashing are attached.

A thin wedge of wood, plastic, or composite placed under and beside a frame to plumb, level, and square the unit while transferring loads to the structure.

The condition of being exactly vertical, checked with a spirit level on the frame jambs so the sash operates and seals correctly.

The condition of being exactly horizontal, checked at the sill and head so the unit sits true and does not rack.

The condition in which frame corners form true right angles, verified by measuring diagonals or using a square, preventing binding and air leakage.

Distortion of a frame into a parallelogram shape from uneven shimming or structural movement, which causes sash binding and seal failure.

A compressible foam rod inserted into a joint before sealant is applied to control sealant depth and allow proper joint movement.

The continuous bead of caulk or sealant between frame and wall that blocks air and water infiltration and accommodates minor movement.

Uncontrolled outdoor air leaking into a building through gaps at frames, sash, and joints, measured in rating standards for performance.

Flexible material at sash and frame contact points that compresses to seal the operable opening against air and water leakage.

The movable or fixed framework holding the glass in a window, which slides, cranks, or swings within the surrounding frame.

The glass or insulated glass unit within a window or door, along with the setting method and seals that hold it in the sash.

Two or more panes separated by a sealed spacer containing desiccant or gas, improving thermal performance over single glazing.

The rate of heat transfer through a window assembly; lower values indicate better insulating performance in rated products.

A replacement technique using formed metal or vinyl trim to bridge from the new unit to the existing exterior wall, often with sealant.

Exterior casing attached around a window or door frame that covers the gap to the wall and provides a nailing surface and drip edge.

A projecting profile above exterior trim or a door head that sheds water outward and prevents it from running behind the cladding.

A fastener such as a screw or bolt that secures the frame to the structure through the jamb or fin, resisting wind and operating loads.

A framed sub-frame set into a masonry or concrete wall to create a precise opening and fastening surface for a window or door.

An opening formed in brick, block, or concrete, typically requiring a buck or clip anchors and careful flashing at the sill.

The movable panel of a door, hung in a frame or on hinges, whose fit and clearance affect sealing and operation.

The sill component at the bottom of a door opening that provides a weather seal and a transition between exterior and interior floor levels.

A window or door section designed to open, such as a casement, awning, or slider, requiring correct hardware and weatherstrip alignment.

A non-opening window or door section, often mulled beside operable units, that still requires full flashing and sealing.

Joining two or more window or door units side by side with a structural or non-structural connector to form a combined assembly.

Heat-treated safety glazing that breaks into small fragments, required in hazardous locations such as near doors and low sills.

Glass or plastic meeting impact-safety standards, marked with an identifying label, used where breakage could injure people.