Typical Parts of a Roof ( by raghad)

Typical Parts of a Roof

Below you will find the major roof components illustrated and briefly defined.

• Dormer - the structure (walls and roof) around a window that projects from a sloped roof.
• Roof Truss the skeleton of the roof. A framework of beams that support the roof.
• Rafters The beams that run from the top of the roof to the bottom. Part of the roof truss.
• Decking or Sheathing Panels that cover the rafters and to which the roofing material (shingles, metal panels, etc..) are attached.
• Underlayment often called tar paper this heavy felt paper (synthetic materials are available as well) is placed on top of the decking before the roofing material is installed to offer an additional layer of protection from moisture.
• Drip Edge edging that is placed at the end of the roof (end of the eaves) used to allow water to run-off and drip clear of underlying construction.
• Fascia trim used to cover the rafter end of the eaves. Often where gutters are attached to the house.
• Soffit a finished underside of the eaves. Covers the area between the end of the eaves and the house.
• Valley - internal angle formed when by the intersection of two sloping roof planes. The intersection of a cross hip or cross gable roof.
• Hip - external angle formed by the intersection of two sloping roof planes.
• Gable triangle shaped part of the end of a building underneath the roof and above the main portion of the house.
• Ridge the highest point of the roof that runs the length of the roof.
• Flashing - Pieces of metal used to prevent the seepage of water around any intersection or projection in a roof, such as vent pipes, chimneys, valleys, and the joints at vertical walls.
• Starter Strip - Asphalt roofing applied at the eaves that provides protection by filling in the spaces under the cutouts and joints of the first course of shingles.

MODERN ROOFING SYSTEM

 Roofing systems come in a variety of forms, from shingles and tile to steel and asphalt. In some cases, culture influences the type of roofing system, such as tile use in areas with ties to Spanish culture. In areas with extreme weather conditions, such as high winds, steel roofing may supersede the more fragile shingle. In all cases though, the roofing system plays a critical role in maintaining the integrity of the home's envelope (temperature, moisture, and air pressure control).

The type of the modern roofing system:
1.Thermoplastic Roofing - TPO roofing systems are among the fastest growing commercial roofing systems. Made of an especially durable material with a low-temperature flexibility and a high-temperature tolerance, these roofs are exceptionally resistant to ultraviolet, ozone and chemical exposure. TPO roofs can be expected to have a lifespan of 20+ years, and also feature a high resistance to fire, punctures, chemicals and high winds.


 http://www.kirberg.com/thermoplastic-membrane-roofing.html , Date:19.September.2012.

2.EPDM Roofing: EPDM roofing offers superior durability and versatility, making it one of the longest lasting types of commercial roofs available. EPDM commercial roofing systems are also typically easier to install, maintain and repair than most other types of commercial roofs.
 EPDM roofing is short for Ethylene Propylene Diene Monomer roofing - otherwise known as rubber roofings. An EPDM roof is a single-ply membrane, meaning there is only one layer of roofing material. EPDM thickness ranges from 30 mils to 100 mils, with the most common thickness being 45 or 60 mils.


 http://www.kirberg.com/epdm-roofing.html,Date:19.September.2012.
3. Photovoltaic Panels: As energy costs continue to rise and America looks towards green and sustainable energy, many building owners are turning to solar energy roofing systems. PV solar panels installed over a rooftop or used with glass, membrane and roof-mounted tile, absorb sunlight and convert it to energy that can be used to power a building. Although not in wide use, PV panel roofs offer great potential to conserve energy and control skyrocketing costs.

 
 http://www.kirberg.com/photovoltaic-panel.html,Date:19.September.2012.
4. Green Roofs: Perhaps of all the types of commercial roofs available today, green roofing systems have experienced the greatest surge in popularity in the last few years. Sedum green roofs are typically flat roofs that are partially or completely covered with vegetation and soil and planted over a waterproofing membrane. Green roofing systems reduce the urban heat island effect by soaking up heat and also are found to dramatically improve a roof's insulation value - lengthening the lifespan of the roof by as much as two to three times.


http://www.kirberg.com/green-roof-systems.html,Date:19.September.2012.
 Green Roofs can be achieved using a standing seam system as a robust component of the system. Traditionally single ply sheets were used as a base for the green roof matt. Aluminium standing seam sheets offer the ability to enable the laying of larger roof areas with out the high risk of leaks caused during the installation of the soil and clay system over membrane. Extensive green roofs can be subdivided into a range of different systems dependent upon the composition and depth of the substrate and on the plant species used.


Reference: Kirberg.com (1920) Types of Commercial Roofs | Commercial Roofing. [online] Available at: http://www.kirberg.com/types-of-commercial-roofs.html [Accessed: 19 Sep 2012].
BY:XI LIN

•  Traditional roofing system: (by: raghad)

Roofing systems come in a wide range of materials and designs. Traditional roofing systems incorporate asphalt, metal, or concrete materials, though asphalt-made roofs are the most commonly used in the U.S. 

Nearly four-fifths of all homes in the United States use asphalt-shingled roof designs, according to Networx Systems roofing specialists. Asphalt materials provide a low-cost option that’s easy to install compared to other roof designs. Other traditional roofing materials, such as concrete, metal and wood or shake roofing, may carry longer warranties than asphalt as well as offer noise insulation and added durability. With each type of material, homeowners have a variety of options in roof styles. And while asphalt exists as the most commonly used material, it also requires the most maintenance compared to other roofing materials.(1)

• for more information u can visit this website:  http://www.builderbill-diy-help.com

  
  

Metal roofs(2)

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references:

(1) Ehow.com (2008) Foam Roof Vs. Traditional Roof | eHow.com. [online] Available at: http://www.ehow.com/info_12137176_foam-roof-vs-traditional-roof.html [Accessed: 19 Sep 2012].

(2) Google.com.my (n.d.) Google Image Result for http://www.builderbill-diy-help.com/image-files/rf-trad-section.gif. [online] Available at: http://www.google.com.my/imgres?imgurl=http://www.builderbill-diy-help.com/image-files/rf-trad-section.gif&imgrefurl=http://www.builderbill-diy-help.com/roof.html&usg=__fdxLOgCXbWzeqVpFYKQ2xJ5W8Rk=&h=250&w=478&sz=5&hl=en&start=10&sig2=a_83lK0GxxOJjJYwVzEQaw&zoom=1&tbnid=wBJiu_EpdxwlnM:&tbnh=67&tbnw=129&ei=rHhZULq3NZO5hAfL1YHICA&prev=/search%3Fq%3Dtraditional%2Broofing%26um%3D1%26hl%3Den%26sa%3DN%26gbv%3D2%26tbm%3Disch&um=1&itbs=1 [Accessed: 19 Sep 2012].

ROOF STRUCTURE

FROM PDF 

http://www.unitcare.com.au/pdfs/roof_structures_explained.pdf


Talks about:


The types of roof structure

Traditional roofs can be divided into three main types of structure:
• Single roofs.
• Double roofs.
• Trussed roofs.


Modern construction methods as it  makes use of another type of roof structure and this is known 
as trussed rafter roofs



BY DEBORAH MWEMA

ROOF COMPOSITION FOR COMMERCIAL BUILDINGS

Most Common Components of a Commercial Roof System

Cants, parapet walls, and curbs on your commercial roof system

One of the most important and valuable parts of a roof system for exterior water entry is the point at which the horizontals of a roof deck and a vertical surface or penetration intersects. A majority of roof leaks occur at these flashing junctures. Designers should carefully design all flashing details around curbs and cants.

Drainage from commercial roofs

A slope of 1-inch in 4 feet is about the minimum practical slope, and even with this it is probable that for large surfaces there may still be depressions where some water will pond.

What are scuppers, through wall scuppers, and drains used for?

A roofs drainage system includes scuppers, through wall scuppers, drains (leaders), as well as the slope provided by the structural deck, tapered insulation, crickets, and sumps. The primary function of the drainage systems is to prevent the retention of water on the roof by removing water as quickly as possible.

Field of a roof system

The field of the roof is a major part of the roof system. This is usually the largest portion of the roof system excluding penetration, curbs, cants, flashing, walls, etc. The field of the roof system is considered to be less detailed than other portions of the roof.

Flashing details on a commercial roof system

Flashings intercept water flow down parapets, down walls of higher adjacent construction, and down roof penetrations diverting it to the membrane. The membrane then carries it to the roof drains, gutters, and other drainage systems.

Roof Penetrations

When inspecting a leaking roof, you should look for poor flashing details - at penetrations, at roof edges, or where a roof changes planes - where areas are much more likely to be the cause of a leak than the roof field itself.

Structural design and available decks
Successful roof systems, along with other factors, rely on sound roof decks. The following provisions should be included in a building's structural design and in the design of a roof deck.

Unventilated roofs/vapor barriers

Roof designs that provide no ventilated space between insulation and roofing present a more difficult problem of moisture control. Sloped roofs may allow some vapor loss to outside if the surface is shingled or tiled. In low-sloped or flat roofs, the roof membrane is a vapor barrier, in some cases more impenetrable and more complete than any provided on the warm side of the insulation.

Tapered roof insulation systems

Roofing professionals agree there is a need to drain water off a roof surface soon after a rainstorm. Positive drainage is an important aspect of good roof systems.

Insulating your commercial roof system

If you think energy bills are taking a big chunk of change out of your pocket, you are not alone. Americans spend more than $115 billion annually on fuel and electricity for their homes and businesses. On average, heating and cooling (space conditioning) account for about 45% of the energy homes and businesses use. Though energy uses vary, there are many ways to lower your energy bills.

What are the uses for expansion joints on your roof system?
Expansion joints are structural separation between roofing material, which helps eliminate the free movement between elements without damage to the roofing or waterproofing system.

REFERENCE

Lakechamplainroofing.net (2008) Roof Composition. [online] Available at: http://www.lakechamplainroofing.net/roof-comp [Accessed: 19 Sep 2012].

BY DEBORAH MWEMA

ROOF CONSTRUCTION

Beautifully designed house with flat roof

Roofs shapes vary considerably in both cost and construction. A continuous Gable Truss is usually the most economical. A Butterfly Roof is a more expensive option due to the need for box gutter detailing, engineering requirements and the difficulty of installation. The most common roof types are:

• Hip and Gable - There are many types of this common roof structure.
• Flat - While they appear flat, they always have some pitch for water run off.
• Skillion - This is flat roof that has a visually significant pitch
• Butterfly - Two skillioned roofs with a box gutter in the middle.

Butterfly roof design with centre gutter

There are 4 measurements that define a roof:

• Span is the horizontal distance between the walls.
• Going is the horizontal distance from the wall to the apex.
• Rise is the vertical distance from the top of the Top Plate to the Ridge
• Pitch. For rafters this is the angle of the rafters taken from the pitching point on the top plate of the wall to the highest point on the underside of the rafter. (The greater the pitch the faster water flows of it and the more chance of gutter failure.)

Roof Terminology

Heavily boxed gabled roof used to create verandah

• Ridge. This is the horizontal straight apex of the roof.
• Hip.This is the sloping apex of a roof that starts at the crown and slopes down to the Facia Board.
• Valley. The Valley is only seen on an L shapes roof. It is the sloping surface from the Ridge to the Facia Board
• Crown.This is the meeting of the Ridge line and the Hip.

Hip and valley roof

Conventional Roof Construction

Full conventional roofing is rarely undertaken today due to the advent of roof trusses. However small amounts of conventional roofing are used when additions occur to an existing roof or when a truss can not be used in an area of the roof where something non-standard occurs. Conventional roofing is labour intensive and far more expensive than truss roofing.

Roof Structure Terminology

• Top Plate. This is the continuous timber beam on top of the walls that supports the roof structure.
• Ceiling Joists. These are the horizontal members that provide a structure to fix the ceiling, and support and fix the diagonal Rafters that define the roof shape and are attached at the top to a Ridge Beam.
• Purlins run horizontally and parallel to the Ridge Beam and perpendicular to the roof slope. They are fixed underneath the Rafters and help prevent roof sag.
• Struts and Props. These are fixed between the Purlins and Joists and an integral part of the load bearing.
• Soffit Bearers. These are between wall and the Facia and allow the Soffit Lining to be fixed.
• Soffit Lining. This is the horizontal sheet cladding underneath the eaves. Eaves. Eaves are the overhang of rafters beyond the supporting wall line.
• Hanging Beams. These beams are placed between load bearing walls and are perpendicular to the Ceiling Joists. They reduce the span of the ceiling Joists are tied to the Hanging Beam with hoop iron straps.
• Facia Board. This is the vertical board that is fixed to the end of the rafters and has both a structural and aesthetic function of enclosing the eaves.
• Barge Board. This is similar to a Facia Board but it is parallel to the rafters, on an angle at the skillion end of a gable
• Roofing Battens. Roofing Battens are fixed onto the outer side of the Rafters. While they have a small structural function for the overall roof frame, they are principally the support for the roof cover. If the roof cover is galvanized iron they are laid at the same time as the roof frame. In other cases they are normally supplied by the roof cover contractor.
• Sarking. Sarking is a strong, moisture proof, reflective, metallic building paper which is placed over the rafters but underneath the roof batons. The sarking runs to the roof gutter and the reflective side should always face outwards to repel heat.
• Collar Ties. These are horizontal timber beams between the Rafters that stop the Rafters spreading.
• Ridge Beam. This is the horizontal timber beam at the apex of the roof. It has no structural function but is the member against which the high end of the Rafters lean. It ensures that the Rafters meet in a straight line and stay upright.

Roof Trusses

The trusses support the roof cladding load and transfer it evenly into the walls.

A truss roof frame is a series 2D prefabricated frames, most often (but not always) triangular shape, that are arranged in parallel and tied and braced together to form a rigid three dimensional structural unit.

The most common is the simple, centre/single pole "King Post Truss", however there are a variety of other simple "WW" configured trusses, some of which are cantilevered, truncated and skillioned according to the roof shape requirements.

It is the most common and least expensive method of roof construction for houses with a simple pitched roof with a flat ceiling (and is a great place to run wires for lights , and service pipes to bathrooms and kitchen areas), however it is not possible to have a loft with roof truss construction. For a loft a conventional roof could be used.

Flat, Skillion and Vaulted Roofs

Modern skillion roof (Photo by Bill Bradley)

Flat or skillion roofs tend to be "stick" built i.e. cut to length and assembled on site.

Skillion roof

This is normally a single sloping roof surface, not attached to another roof surface. The term skillion can also be used for a smaller addition to an existing roof, where keeping to the same slope (roof pitch) puts the skillion roof lower than the ceiling height of the main structure. In this case even though the main roof has a flat ceiling, the skillion part will have a sloping ceiling line to maximise the ceiling height.

Vaulted roof

Vaulted ceilings are not typically constructed using the same pitch as the roof and are often framed using scissor trusses. Cathedral ceilings are often used with vaulted roofs. Note that insulation becomes an issue for flat and low pitched roofs where there is no air flow. (See Insulation Section). There, insulation should be placed both on top of the ceiling sheets and on top of the sarking and underneath the roof sheeting. Some rigid ceiling sheets can double as cladding and acoustic insulators. (See Ceiling section.)

Flashing and Sarking

Flashing is a continuous piece of malleable sheet metal or other impervious material that is installed to direct water into safe surface areas and prevents it from entering the structure the building.

Flashing may be exposed or concealed. Exposed flashing is usually of a sheet metal, such as aluminium, copper, painted galvanized steel, stainless steel, zinc alloy, lead or lead-coated copper.

Roof flashing

This is placed around protrusions from the roof of a building (such as pipes and chimneys) or the edges of other roofs) to deflect water away from seams or joints.

Wall Flashing

Wall flashing is typically found at interruptions in the wall, such as windows, doors and points of structural support to prevent water from entering the wall cavity or structure.

Sarking

Sarking is a waterproof paper, bituminous or plastic sheet (that comes in a roll) that is usually concealed within, or is laid next to, a wall or roof frame.

Reflective foil sarking is used to reflect heat and stop condensation forming on the underside of a roof. (Low pitches roofs have less air flow and more condensation than pitched roofs.)

Wide spans between battens and purlins on a roof may require heavy duty reinforced sarking, or a support net under sarking e.g. chicken wire.

REFERENCE

Homedesigndirectory.com.au (2012) Roof Construction. [online] Available at: http://www.homedesigndirectory.com.au/construction/roof-construction.shtml [Accessed: 19 Sep 2012].

BY DEBORAH MWEMA

TYPES OF ROOFS

INTRODUCTION

Roofs are the coverings on top of a building or a house. Roofs are a very essential part of a buildings and houses as they protect the inner part of the building from rain, storms, snow and extreme of temperature. Without a roof, a building is incomplete.

The concept of building a roof or a shelter is not new. The earliest of men constructed a roof made of straws, leaves and branches to cover their places; in fact man started building roofs before houses.

As human civilization developed the concept of houses evolved and so did the materials and styles of roofs in constructions. Today there are many different types of roofs that are found over houses and buildings. These roofs are built according to their purposes and for the added beauty they bring to the house. Some of the common types of roofs are mentioned below:

A flat roofed building. The most common type seen in cities.

Source: Flickr byy ell brown

A house being constructed with a sloping roof

Source: Flickr by Bryn Pinzgauer

Flat Roofs

Flat roofs are one of the oldest and the simplest type of roofs. These roofs are easy to recognize and are the most common roofs for buildings. They may not however be very popular among houses these days. Flat roofs have a shallow pitch which is around 1-2 degrees.

There are many advantages as well as disadvantages of flat roofs. The main advantage of flat roofs is that the construction of building becomes easier and the walls do not have to be perpendicular or parallel to each other. The main disadvantage is that it has no slopes or a tilt because of which water and debris may accumulate on the top.

They also require a high maintenance. Therefore flat roofs are best suited in areas which are dry and do not have much rainfall. Many flat roofs although do have a drainage pipe at the end; it is still not a very preferable roof for houses. It is best suited for tall buildings and warehouses.

Sloping Roofs

Sloping roof is a general term applied to any roof that is either slightly or completely tilted.

These roofs are one of the most common residential roofs. Unlike the flat roofs the major advantage of sloping roofs is that they do not let the water or debris to accumulate.

Example of a gabled roof.

Source: Flickr by Dept of Energy Solar Decathlon

Gable Roofs

Gable roofs are one of the most famous types of roofs.

A single gable roof is made up of two rectangular roofs and a bit slanting, meeting at a point to form a single roof.

The line where they meet is the ridge line. Gable roof can also be called the typical house roof.

Salt box style roof construction

A gambrel roof

Source: Wikipedia by Lars Lentz

Salt Box

Salt box is a very stylish type of roof which is very interesting to look at. Like the gable this type of roof is also made of two roofs which meet at a ridge line but in this roof they meet to form a triangle and the salt box's one side of the roof is bigger while the other is shorter i.e. it forms a lopsided triangle. This concept of roofs evolved during the twentieth century.

Saltbox is best suited for houses but some office buildings also have saltbox roofs

Gambrel Roof

Gambrel roof is basically a type of gable roof in which one side is steeper than the other. The gambrel roof has vertical gable ends and the roof hangs over the pretense of the house.

This roof is more popularly used as a barn roof. It is a Dutch inspired style of roof.

Mansard Roof seen in a building in England

Source: Flickr by Jim Linwood

Pyramid roofs on top of buildings in a city.

Source: Flickr by thienzieyung

Hipped roof in a banglow

Source: Wikipedia by blahedo

Mansard Roof

Mansard roof may resemble to the gable roof but the two roofs have many differences. The Mansard roof has four slopes.

These slopes are present on the all the four sides of the house.

The lower slope is vertical and steeper than the upper slope and the upper slope may not be very visible. This style of roofing comes from the French.

Pyramid Roof

Pyramid roofs are highly stylish and modern types of roofs.

These roofs as their name implies are shaped like a pyramid. These roofs are best suited for huts, houses or small structures such as pool houses.

Hip Roof

Hip roof resembles the pyramid roof as it too has four slopes elevated and joined together.

But unlike the pyramid roofs, the slopes of hip roofs do not meet at a single point in fact the top of the roof is flattened in a way that the four corners of the square are occupied by the slopes.

They too are best suited for small structures.

REFERENCE

Irfan, H. (2012) Types Of Roofs. [online] Available at: http://hamadirfan.hubpages.com/hub/Types-Of-Roofs [Accessed: 19 Sep 2012].

BY Deborah Mwema

CATEGORY OF TOPICS

ROOFING SYSTEM

• TYPE OF ROOFS
• PARTS OF ROOFS
• TRADITIONAL SYSTEM ROOFING
• MODERN ROOFING SYSTEM
• METHOD OF CONSTRUCTION
• INNOVATION AT MOMENT FOR ROOFING SYSTEM
• MAINTENANCE AND COST ESTIMATION FOR ROOF SYSTEMS
• DISADVANTAGES AND ADVANTAGES
• CONCLUSION

BY Deborah Mwema

(ROOF SYSTEM) INTRODUCTION

"A roof is the covering on the uppermost part of a building. A roof protects the building and its contents from the effects of weather and the invasion of animals. Structures that require roofs range from a letter box to a cathedral or stadium, dwellings being the most numerous.

In most countries a roof protects primarily against rain. Depending upon the nature of the building, the roof may also protect against heat, sunlight, cold, snow and wind. Other types of structure, for example, a garden conservatory, might use roofing that protects against cold, wind and rain but admits light. A verandah may be roofed with material that protects against sunlight but admits the other elements.

The characteristics of a roof are dependent upon the purpose of the building that it covers, the available roofing materials and the local traditions of construction and wider concepts of architectural design and practice and may also be governed by local or national legislation."[1]

[Derived from http://www.welsh49.com/services/roofing on 12 September 2012] [2]

References

[1] En.wikipedia.org (2012) Roof - Wikipedia, the free encyclopedia. [online] Available at: http://en.wikipedia.org/wiki/Roof [Accessed: 12 Sep 2012].

[2] Welsh49.com (2012) Roofing Baltimore | Towson | Columbia | Ellicott City | Welsh Construction Remodeling, LLC. [online] Available at: http://www.welsh49.com/services/roofing [Accessed: 12 Sep 2012].