A pitched roof is a roof that has a sloping surface or roofs with an angle typically approaching 20 degrees. It is a bi-fold, bi-planer roof at its highest point, with a slope. More precisely, a pitched roof needs a pitch of more than 10 degrees or a two-slope roof that sits on a central ridge.
Pitched roofs feature a more classic look. To ensure maximum security, they remain the most effective and efficient solution in humid and cold weather.
Parts of Pitched Roof
The followings are the major parts of pitched roofs.
- Gable
- Flashing
- Purlines
- Fascia
- Battens
- Rafter
- Ridge
- Hip
- Eaves
- Joist
Gable
The upper part of the Triangular Wall at the end of a ridge roof.
Flashing
A stripe of impermeable material, typically metal used to exclude water from the junction between a roof cover and another part of the structure.
Flashes are provided to prevent moisture from entering the wall and roof through joints in copings, parapet walls, and other roof plane penetrations.
For More Details: Civil engineering
Purlins
These are horizontal elements, mounted on wall-to-wall main rafters to sustain a roof’s standard rafter when the span is long. The purples are made of wood or steel. The purlins ‘ top surfaces are to be flat and plane. They are to be colored before being mounted on board.
Fascia
This is a wooden board placed at eaves to the bottom of the rising rafter. The ends of the membrane protecting the lower-most roof lie upon it.
Battens
These are thin wood strips that are attached to common rafters or ceiling boards to support roofing materials such as tiles, sheets, etc. Batten might be made of metal or plastic, too.
Rafter
Rafter is a part structural to a pitched roof. This typically begins from roof support (column or wall) to the ridge or hip support. Several rafters are used side by side to assist the purlin with a fair size. All timber rafters are used in typical home building. Steel rafters are used for large commercial hut businesses.
Ridge
The triangular junction angled in opposite directions at the top of the two elevating roof surfaces.
Hip
The outside angle (more than 180 degrees) between two intersecting slopes of the roof created by the inclined ridge.
Eaves
In the roof, the lower portion of the inclined roof that protrudes beyond the wall’s exterior. The primary feature of eaves is to spill rainwater directly on the outside wall from the building. I give protection against sunlight, too. Eaves are rarely highly decorated to maximize architectural elegance.
Types of Pitched Roof
- Closed Couple Roof
- Trussed Rafter
- Mono Pitch Roof
- Couple Roof
- Purlin Roof
- Collar Roof
Closed Couple Roof
- Added ceiling joists, a piece of wood extending horizontally between the rafter posts, made the building a lot safer. The joist serves as a bond avoiding the wall’s external deflection and extending the total roof width to about 5 m.
- Instead of the Wall Plate, joists are secured to the rafter feet to negate any potential deflection. Therefore a secure connection between the rafter and the joist at the ceiling is critical.
- By using struts, the benefit of this type of roofing is that much of the roof space could be used for storage and that area could be used for housing if appropriate.
Trussed Rafter
- The fink or ‘w’ truss is the most common form of the trussed rafter in modern house construction. This consists of a rafter comprising W shaped tension and compression members. This trussed rafter is capable of spans up to 12 m and can be designed to accommodate many different pitch angles.
- The most significant advantage is the off-site assembly of the trussed rafter which speeds up the whole construction process.
- The most significant advantage is the trussed rafter off-site installation which accelerates the entire construction cycle.
- Including diagonal bracing from eaves to the ridge on the underside of the rafters ties the entire structure into one entity rather than a set of independent trusses, providing protection against potential wind movements failure.
Mono Pitch Roof
- Slopes that are usually used to construct extensions from one side or part of a building to another.
- This involves a set of rafters that are attached to plates at the top of a wall, and the rafter feet are nailed to a wall plate that uniformly distributes the load across the supporting surface.
- Joists are built to shape level ceilings and the height could be increased.
Struts that keep rafters from sagging are widely used to protect joints.
Couple Roof
- The pair roof is the simplest form of the pitched roof, which comprises of two lengths of rafters leaned against each other, joined where they intersect at the peak.
- Very small duration of some 3.5 m.
Purlin Roof
- Roof spans could be increased by introducing purlins without compromising wall stability, increasing the size of rafters or attracting extra costs.
- Purlins enable rafters to get extra support and become lighter and thinner, allowing a possible 8 m span.
- The advantage of this form of roofing was that by using struts, much of the roof space could be used for storage and finally, the space used for accommodation could be used.
Collar Roof
- The height of the ceiling joists is elevated, so that the roof allows for the building of any upper rooms in the roof space, thereby raising the height of the external walls significantly.
- The downside of this approach is that it reduces the restricting power by raising the ceiling joist, increasing the weakness of the supporting walls and reducing the distance to around 4 m.
- The height of the ceiling joist could be raised up to a maximum of 1/3 of the roof height to maintain stability.