Roofing Component Terminologies

It is essential to be familiar with the various roofing terminologies to help you choose the right products for your project and to determine which warranties are best. Below are some definitions for important terms that relate to roofing.


Protective layer that covers the roofing system’s sheathing or waterproofing.


This is a protective barrier to prevent water from passing through walls or roofs.

Drip Edge

Section of flashing, which directs water dripping from the roof edge down onto another surface or away to a wall.

Cripple Flashing

Fitting is placed below the rafters’ bottom edges or along eaves; it prevents moisture from entering foundation wall. Rainwater can penetrate roof decking.

Verge Cap

Concrete pieces, slate tiles, metal and stone are all acceptable options.

Chimney Flash

The flashing covers the roof and chimney junctions to keep water out of the attic. It can withstand heat from the fireplace without any damage. It features a sloped eavestrough that runs down its base so moisture doesn’t get into the drainage plane.

Balloon Framing

A method for timber framing that uses curved timbers. Corner posts are not required for support. Instead, diagonal bracing is used for rigidity. Each floor is raked to the center, creating a dome effect which minimizes structural stress from weather loads.


Asphalt, wood, slate and fiberglass shingles are made out of wooden slats. They are stapled horizontally, with tabs at both ends, for attaching to a roofing deck. The shakes are fastened in place using nails set into each tab. Asphalt shakes have plastic beads embedded beneath each tab to prevent leakage.


The incline and fall of a roof’s surface are expressed in terms of rise over run. For example, 2/12 is 1/6 inch per feet (an 8-foot-long section rises 24 inches); 4/12 represents 2/3 inch (an 8.8-foot segment rises 16 inches).


A exterior window structure that is positioned from the main roof of a home and has one or two windows on the four sides. In some parts of the world, dormers are called “balconies”.


The vertical walls on either side of a building’s facade, which extend beyond the main roof’s plane and support an elevated upper story (or stories), are called “gable walls”. The bracketing, also known as “trimmers”, is attached to the roof rafters to support the gable wall.


Placed along an interior or external wall as a floor or step, or around a ceiling, or over architraves for doors or windows.


A board that has scrolled ornamentation and is attached to the roof’s edge with no support brackets. The barge boards should be placed at the midpoint between adjoining gables. It may only have one board, or two depending on the style of architecture.


Ends of building roofs which extend beyond exterior walls. Eaves are protected from the rain by being supported by eaves molds, also known as “rakes”. The lower part of the wall below eaves is called an “eave-trough”, and captures water and directs them by gutters to a downpipe for collection in a rain barrel.


A flat structural lat used to underlay a roof decking. Roof decking materials can include wood shakes or asphalt shingles as well as slate tiles and concrete pavers. The tiles prevent water penetration from the roof to interior living areas. Based on thickness, tile can be waterproofed at 5-15 PPI (pounds per square inch). There are three main types available: tile with modified bitumen or architectural properties, as well as two-ply membranes.

Soffit Tray

A metal trough which is placed beneath any type of roof soffit, near the edge of buildings where water is collected. In that trough, water flows to the catch basin.

Catch Basin

These are a series of rectangular sections of concrete and plastic pipe that is attached to rain gutters. They act as a holding place for standing water, in case it rains.


A pipe that allows water from roofs to drain down to the ground. They lead to the ground from the first level and are attached to structures at corners or near walls where water can run off into an exterior drainage system.

Decorative metal shields

To prevent flanking emissions and vandalism, decorative metal bands are placed around columns and posts. They also provide a decorative appearance for the property. In some cases it is used as an anti theft device.


The interior angle formed by each member of the truss. It is also known by the term “the web” or truss. But this term is a mistake. Web implies something solid, when in fact these chords are hollow rectangular tubes with holes through them along their length. This construction makes them lighter and easier to make than solid wood members.


A floor made of flat-flooring materials such as composite or planed wood laid over joists. Cedar, redwood (treated pine), pressure-treated pine, and cedar are some common decking materials.

Roof Breech

The top of most chimneys, where smoke is drawn up, creates a suction area for air to enter the chimney. When a fire is lit in a fireplace or stove, this is called the “suction opening”. If this area is blocked by ice most of the time, heat cannot escape through the top opening. Backdraft can cause carbon monoxide poisoning which reduces oxygen in your home.


A series of constructions that attach to columns, posts, or walls. They form a railing which consists of small balusters interspersed with open spaces. This is used for safety reasons. Balustrades add beauty and elegance to properties while also protecting against falls from balconies or stairways.


It is a technique where stone slabs of different sizes are placed side-by-side to create decorative patterns for architectural structures.

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