Siding Glossary

home siding glossary of terms

Siding Glossary

The glossary of terms that follows provides some of the common terms associated with siding, soffit and fascia that you may encounter when reviewing companies and products.

Siding, Soffit and Fascia Terms Explained: A Basic Glossary

Backerboard: A board or other flat surface nailed between the studs of an exterior wall that provides a surface on which to attach siding.

Battens: Strips of wood used to seal joints in wood siding.

Beveled: Tapered, opposed to rectangular, clapboards.

Backer Tab: Provides support for non-insulated 8" siding at panel overlaps (joints), and behind panels at corners to ensure a smooth installation.

Butt Edge: Bottom edge of siding/soffit panel or accessory piece opposite the nailing slots. Locks onto the preceding panel.

Butt Lock: The bottom edge of a vinyl siding panel that locks into the previously installed panel.

Center Butt: A crease in the center of a siding panel that makes the siding look like two pieces instead of one piece.

Channel: Area of accessory trim or corner post where siding/soffit panels are inserted. Also refers to trim itself, and named according to letter of alphabet it resembles (i.e., J-channel, F-channel, etc.).

Clapboard: Long, rectangular wooden siding that is installed horizontally in an overlapping manner.

Composition Board: Sheets of weather-resistant compressed wood fibers used as home siding.

Course: A row of panels, one panel wide, running the length of the house from one side to the other or, in the case of vertical siding, from top to bottom.

Cupping: The warping of wood plank siding.

Double Course: When new siding is laid on top of a layer of shingles or shakes.

D4 Profile: Two four-inch wide horizontal traditional planks per single panel of siding.

D5 Profile: Two five-inch wide horizontal traditional planks per single panel of siding.

Drip Cap/Head Flashing: An accessory installed with vertical siding to ensure that water drips away from panels and does not infiltrate them; it is also used as a vertical base. Also used over windows and doors.

Dutchlap or Shiplap: A more decorative variation on the clapboard style where the face (or width) of the board is beveled for added dimension. The wide trim along the roofline above the vinyl siding.

Eaves: The lower, level part of a roof overhanging a wall.

Exposure (or Reveal): The width of a board of siding.

F – Channel (Molding or Trim): Molding used for trim that is in the shape of the letter F, used to trim the edge soffit just above the vinyl siding, on the wall side. F – Shaped molding used to trim siding that’s installed at a 90 degree angle.

Face: The part of the vinyl panel that is visible once the vinyl is installed

Face Nailing: Action of fastening directly onto the face of panel, rather than using the nail hem slot. Generally not used in siding installation.

Fascia: The trim piece nailed to the ends of a series of rafters or trusses to tie them together at the lower, level end of a roof. The fascia supports the sheathing on the edge of the roof as well as the front edge of the soffit.

Fascia Board: The exterior finish nailed to the fascia that is nailed to the rafter or truss ends that runs horizontally around the roof on which the gutters are mounted. The fascia board forms a drip edge for rain water, as well as hides the end of the roof sheathing and soffits. A horizontal board that runs along the lower end of a roof and covers the joint between the top of the wall and the eaves.

Finish/Pattern: The type of texture or level of gloss of a piece of siding.

Finishing Trim: The finished edge of a piece of panel.

Flange: Material used to deflect water from siding or trim to prevent damage to the home.

Flashing: A type of sheet, usually a metal like aluminum, used at intersections of building components to prevent water penetration, flashings are commonly used above doors and windows in exterior walls and are used under the siding to prohibit water penetration

Frieze: A decorative, horizontal band that connects the top of the siding to the soffit.

F-channel: A manufacturing component of vinyl or aluminum siding systems which have a channel that the planks fit into, used around windows and doors to make a weather tight seal

Furring/Furring Strip: A wooden or steel framing material, usually 1" x 3", used to provide an even nailing base. To “fur” a surface means to apply these strips.

Gable: The upper triangular-shaped portion of the end wall of a house.

Gable Vent: A vent in the gable of a home that reduces head and moisture buildup by increasing the flow of air to the attic.

Inside Corner Post: Provides a means of joining at inside corners where siding butts both sides.

J-Channel: Also J (Molding or Trim): Molding used for trim that is in the shape of the letter J, used to trim the edge of siding on all sides of windows and doors, at rake edges of gables and in other miscellaneous situations.

Lap: To overlap ends of two siding panels to allow for expansion and contraction of siding product.

Lap Siding: An installation technique in which each piece of siding is "lapped" over the previous piece to provide a waterproof barrier.

Lock: The lock, combined with the locking leg, form a "lock" between siding panels or courses of siding panels.

Locking Leg: The locking leg, slipped into the lock, forms a tight connection between siding panels or courses of siding panels.

Miter Joint: The area where two siding panels meet, usually at a 90-degree angle.

Nailing (Hem or Flange): The section of siding or accessories where the nailing slots are located. The part of the siding panel or trim that contains the fastening holes.

Nail Hole Punch: A tool that creates an oval hole in the vinyl siding where the nails will go, allowing for expansion and contraction of the vinyl siding.

Nail Slot: A hole in the nailing hem or flange of the backerboard into which a fastener, nail, or staple is inserted.

Outside Corner Post: Provides neat appearance outside corners for vertical and horizontal sidings. Receives siding from both sides. Deeper post is used with insulated siding, and narrower post with non-insulated siding.

Positive Lock: Ensures that the panels can be locked together, but can also easily slide back and forth for ease in installation. This ensures that the panels stay permanently affixed during adverse weather.

Plumb: A position or measurement that is truly and exactly vertical, 90° from a level surface.

Plywood Siding: Plywood sheets used for siding that often have grooved or decorative outer surfaces.

Positive Lock: A locking mechanism that allows siding panels to move back and forth for simple installation, while ensuring that panels stay permanently attached during inclement weather.

Profiles: The technical term for siding panels used by those in the business. The actual siding panels are called profiles. Some commonly sized profiles are D4, D5 and Dutchlap.

PVC: Polyvinyl chloride is the material used to create most vinyl siding.

Rake: The edge of a sloped roof forming the overhang beyond the wall of a gable roof or other sloped roof.

Scoring: Scratching a straight line into the surface of a siding panel using a sharp tool. The panel can then be bent at the location of the score mark and snapped into two pieces with clean edges.

Shadow Line: The shadow shape cast by a home's siding.

Siding Removal Tool: A tool with a curved metal end that is used for removing attached panels of siding.

Snaplock Punch: A handheld tool used to form crimps into siding panels, allowing cut panels to fit tightly into the appropriate slot in the trim.

Soffit: The underside of elements of a building, such as overhangs, staircases and beams. Also refers to the material used to enclose the horizontal underside of an eave, cornice, or overhang. Some soffit panels may also be used as vertical siding.

Square: Unit of measure for siding equal to 100 square feet (or a 10-foot by 10-foot wall section).

Square Feet: (also known as Exterior Square Feet) ; Exterior Square Feet is a term used to denote the total amount of siding material needed for a particular siding job including material waste.

Starter Strip: A home siding accessory which secures the first course or row, of siding to the wall framework. Used with horizontal and vertical siding.

Strapping: Wood or metal affixed to the exterior of a building that provides a smooth surface on which to attach new siding.

Stucco: An exterior finish for masonry or frame walls, usually composed of cement, sand, and hydrated lime mixed with water and laid on wet.

T-Channel (T-Molding or T-Trim): T-shaped molding used as a trim between the ends of two panels.

Tongue and Groove (T&G): Tongue and groove, a connection system between components, like wood, in which the tab or tongue of one board is placed into the grove at the end of another board

Vinyl Siding: Low-maintenance, plastic siding that is available in many colors and styles.

Wall Cladding: Another term for siding

Wall Sheathing: Sheets of plywood or wood planking used to cover the wall framework of the house. This is the material that the siding is nailed to.

Weep Holes: A small hole in the bottom butt edge of the vinyl siding panel, or other accessories, allowing condensation to escape.

Windload Pressure: Is a measurement of how well a panel might perform in high wind areas

Window Head Flashing: Possible alternative to J-channel to receive siding over doors and windows and as a base flashing on vertical siding installations.

Wood Shakes: Siding that is made from hand-split, rough, cedar shingles.

Wood Shingles: Pieces of wood siding that are machine cut, smooth, and uniform. They are installed in an overlapping pattern.

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