Essential 37 Roof Parts: Importance and Leak Proofing
Roof consits of different types of parts. Each part has a specific task and contribute to the functionality of the roof in different ways. Roof consits of mainly 20 components those can be catogerized into structual components, decking/sheating, underlayment and moisture barrier, surface components, flashing and trim, ventilation component, edge and overhangs, and other elements.
Every roof does not includes all of the parts mentioned below in the document. Roof components are available based on the type of roof, roofing material, climate region, and design feature. As waterproofing experts, Aqvize we, do waterproofing and maintenance services on all of the roof types. Our experts prepared this guide with useful images and an introduction of each part and why it is important to the roof.
Structural Components of the Roof
1. Rafters
Rafters are the sloped beams that run from the ridge to the eaves of the roof. They create the roof’s basic shape and framework and support the roof deck and outer layers. Rafters are crucial for bearing the weight of roofing materials and transferring that load to the walls.
2. Trusses
Trusses are pre-engineered triangular frames that replace traditional rafters in many modern roofs. They are designed for strength and efficiency, distributing roof loads evenly across the structure. Trusses are fast to install and ideal for spanning wide distances without the need for interior supports.
3. Joists
Joists are horizontal framing members that typically support ceilings or floors, depending on their placement. In roof construction, they tie walls together and may support ceiling finishes from below. They also help resist the outward thrust of rafters.
4. Ridge Board
The ridge board is a horizontal board at the top of the roof where rafters from each side meet. While not load-bearing, it acts as a guide and connection point for rafters, helping align them properly during construction and stabilizing the roof structure.
5. Ridge Beam
A ridge beam is a structural, load-bearing element running along the peak of the roof. A ridge beam supports the ends of rafters and carries significant weight, making it essential in vaulted ceiling or heavy-load roof systems.
6. Collar Ties
Collar ties are horizontal members installed in the upper third of opposing rafters. Their primary job is to prevent the rafters from separating under load or wind pressure, especially in steep or open attic spaces, and maintain structural integrity.
7. Ceiling Joists
Ceiling joists span horizontally between walls and support the ceiling below the attic or roof. They also serve as ties that resist the outward thrust of the rafters, helping keep the walls from bowing outward under roof load.
8. Lookouts
Lookouts are short horizontal supports that extend from the wall to the edge of the roof or gable overhangs. They provide a base for extending the roof beyond the wall line, supporting fascia and soffit boards, and giving shape to eaves or gables.
9. Gable End Framing
Gable end framing forms the triangular end wall of a gable roof. It supports the roof deck at the gable ends and helps transfer loads to the structure below. It also provides a vertical surface for attaching siding and framing gable vents or windows.
Roof Decking Parts
10. Roof Deck/Sheathing
The roof deck (or roof sheathing) is the flat surface, usually made of plywood or oriented strand board (OSB), that sits on top of the rafters or trusses. It acts as the base layer for all other roofing materials and supports the weight of shingles, tiles, or membranes.
Sheathing is another term often used interchangeably with roof deck. It provides a nailable surface for roofing materials, helps distribute loads across the structure, and adds rigidity to the overall frame of the roof.
Roof Underlayment Parts
11. Ice and Water Shield
Ice and water shield is a self-adhering waterproof membrane that protects vulnerable areas of the roof, like valleys, eaves, and around penetrations (vents, chimneys). It’s crucial in cold or wet climates to prevent leaks from ice dams or wind-driven rain.
12. Vapor Barrier
A vapor barrier is a material layer (often installed inside the attic or under insulation) that resists moisture migration from the interior of the building into the roof structure. It helps control condensation, mold, and wood rot, especially in humid or cold environments.
Roof Surface Components
13. Shingles
Shingles are overlapping roof coverings, most commonly made from asphalt, but also available in wood, composite, or fiberglass. They protect the roof from weather, provide insulation, and shed water. They’re popular due to their affordability and ease of installation.
14. Tiles
Roof tiles, typically made of clay or concrete, are durable and long-lasting. They offer excellent protection against rain, heat, and fire while adding a distinct architectural style. Heavier than shingles, they require a strong roof structure to support their weight.
15. Metal Panels
Metal panels (like steel, aluminum, or copper) are long sheets or sections that form a sleek, durable roof covering. They’re resistant to wind, fire, and insects, and they reflect heat well. Metal roofing is known for its longevity and low maintenance needs.
16. Roofing Membrane
A roofing membrane is a waterproof sheet used mostly on flat or low-slope roofs. Common types include EPDM, TPO, and PVC. These membranes provide seamless protection against water infiltration, making them ideal for commercial buildings or modern homes with flat designs.
Roof Flashing and Trim
17. Flashing
Roof flashing refers to thin metal (usually aluminum or galvanized steel) installed at joints or transitions on a roof to prevent water penetration. It’s used around chimneys, vents, skylights, walls, and other areas where the roof surface is interrupted.
18. Drip Edge
A drip edge is a metal strip installed along the edges of the roof (eaves and rakes). It directs water away from the fascia and into the gutters, protecting the underlying structure and preventing water damage and rot.
19. Valley Flashing
Valley flashing is placed in the valleys where two roof slopes meet. These areas channel a lot of water, so the flashing ensures proper drainage and prevents leaks at this vulnerable intersection.
20. Vent Flashing
Vent flashing seals the area around roof penetrations like plumbing vents or exhaust pipes. It typically includes a metal base with a rubber or flexible collar that fits snugly around the vent to keep water out.
21. Step Flashing
Step flashing is a series of small metal pieces layered between shingles and wall cladding (like siding or brick) along vertical roof intersections. It directs water away from the wall and ensures a watertight seal where the roof meets the wall.
Roof Ventilation Components
22. Ridge Vent
A ridge vent runs along the peak of the roof and allows warm, humid air to escape from the attic. When paired with intake vents (like soffit vents), it promotes continuous airflow, helping regulate attic temperature and moisture levels.
23. Soffit Vents
Soffit vents are installed under the eaves of the roof. They serve as intake vents, allowing cooler outside air to enter the attic and push warm air upward and out through higher vents like ridge or gable vents.
24. Gable Vents
Gable vents are mounted in the walls of the attic, usually near the roof peak on each end. They help ventilate the attic space by allowing air to flow in and out, often used in older homes or in combination with other vent types.
25. Roof Vents
Roof vents, also called static vents, are small, fixed openings on the roof surface. They let hot air escape from the attic passively and are usually spaced evenly across the roof near the ridge.
26. Box Vents
Box vents (also called turtle vents) are a type of static roof vent. They sit flat and box-like on the roof and provide exhaust points for attic heat and moisture. Multiple box vents are often used to cover larger attics.
27. Powered Attic Vents
Powered attic vents use electric or solar-powered fans to actively pull hot air out of the attic. They’re ideal for areas with limited passive airflow and can significantly reduce attic heat buildup, though they need careful installation to avoid pulling conditioned air from the living space.
Roof Edges Parts, and Overhangs
28. Eaves
Eaves are the horizontal edges of the roof that overhang the exterior walls. They help direct rainwater away from the foundation and provide shade and protection to the walls below. Eaves often house soffit vents for attic ventilation.
29. Rakes
Rakes are the sloped edges of a gable roof, running from the ridge down to the eaves. They’re not horizontal like eaves but angled. Rakes often include trim or overhangs to protect the edge of the roof and add visual definition.
30. Fascia
The fascia is the vertical finishing board that runs along the edge of the roof at the eaves and rakes. It caps the ends of rafters or trusses and provides a mounting surface for gutters, while also protecting the roof edge from weather.
31. Soffit
The soffit is the underside of the eaves the horizontal area between the exterior wall and the edge of the roof. It often contains ventilation openings (soffit vents) to allow air into the attic and maintain healthy airflow throughout the roofing system.
Roof Penetrations
32. Chimney
A chimney is a vertical structure that vents smoke and gases from fireplaces, stoves, or furnaces through the roof. It must be properly flashed at the roof intersection to prevent leaks and is often a key structural and aesthetic element of traditional homes.
33. Skylight
A skylight is a window installed in the roof to bring natural light into the interior of the building. It can be fixed or operable (venting), and like chimneys, it requires proper flashing to prevent water intrusion around the opening.
34. Dormer
A dormer is a vertical projection from a sloped roof that includes a window and its own small roof structure. Dormers add usable space and headroom to attics or upper floors, while also enhancing natural light and exterior architectural interest.
35. Gutters
Gutters are horizontal channels installed along the eaves of the roof to collect and direct rainwater away from the building. They protect the siding, foundation, and landscaping by preventing uncontrolled runoff from the roof.
36. Downspouts
Downspouts are vertical pipes connected to gutters that carry rainwater from the roof down to the ground or a drainage system. They’re essential for preventing water accumulation near the foundation and managing roof runoff safely.
Which Roof Part Requires Waterproofing?
Waterproofing is essential in roof areas like roof deck, which is the base for all roofing materials, and areas like valleys (where two slopes meet), eaves (edges where water runs off), and around any flashing (metal seals at joints). As well as roof waterproofing is required for penetrations such as chimneys, skylights, and vent pipes also need extra waterproofing to keep water from seeping into the structure.
Read More About: 9 Types of Roof Waterproofing Membranes
What is Roof Pitch?
Roof pitch refers to how steep a roof is. It’s expressed as a ratio of vertical rise to horizontal run, like 4:12, meaning the roof rises 4 inches for every 12 inches it runs horizontally. Pitch affects water drainage, roof style, and the types of materials suitable for the roof. Steeper pitches shed water faster, while low-slope roofs need more waterproofing.
