Types of Roofing

Slate Roofing
Slate is a fine grained, metamorphic rock, derived from a sedimentary rock composed of clay or volcanic ash, and metamorphosed by heat and pressure.
Slate is a popular roofing material, as it is strong and waterproof. It is also convenient to shape into the standard rectangle shape as used on roofs, as it has two lines of breakability cleavage and grain, making it possible to split slate into thin sheets, ideal for roofing.
Slate roofing is also highly durable, thanks to its chemical stability and thermal stability, thus it is less susceptible to environmental factors. Slate roofs can last very long periods of time as a result.

Tiled Roofing
Tiles are manufactured materials made from hard wearing materials such as ceramic, clay, stone or even glass (though this depends on the use of the tile, as tiles are not used exclusively for roofing). Roof tiles are usually made from clay, though they can be made from slate or wood (known as shingles). Sometimes, modern materials such as concrete or plastic are used, though clay is still most common. Clay tiles will often have a waterproof glaze.
Tiles have been used in roofing for centuries, and thus several different shapes (or 'profiles') have evolved.

Flat Tiles
Flat roof tiles are the simplest type of roofing tile. As the name suggests, they are flat, and they are usually a rectangular shape. When placed on a roof, they are usually layered, and are laid in a repeating, parallel pattern. Flat roof tiles are usually made from wood or stone, though the design is also used for solar panels when used in roofing.
Flat tiles were once limited by an Act of Parliament to a regular size of 10.5 by 6.5 inches. This act has long since been repealed, but the size has remained constant, apart from a slight change to 265 by 165mm in the mid 1970s. Methods of laying tiles have remained surprisingly unchanged also.
Modern tiles have a 'nib', which allows them to be hung from battens (the horizontal pieces of wood which traverse the rafters)

Roman Tiles
Roman tiles are flat in the middle, with a convex curve at one side, and a concave curve on the opposite side, allowing them to interlock.

Single Lap tiles
Single Lap tiles (or pantiles) have a shallow, 'S' shaped profile, allowing adjacent tiles to lock. When laid, they form a pattern similar to a ploughed field. The size of a single lap tile was fixed in the early eighteenth century at 131/2" x 91/2". One of the main disadvantages of a single lap tile is the shape, which can make the cutting of the tiles to fit a 'hip' or a 'valley' on a roof. The underside of a single lap tile is usually torched with a lime or a clay mortar, to prevent rail or snow penetration.

Mission (or Barrel) Tiles
Mission/Barrel tiles are semi-cylindrical tiles, traditionally made by forming clay around a log. The tiles are then laid in an alternating concave/convex pattern. These tiles are common in France, Spain and Italy, particularly in rural regions.

Peg Tiles
Peg tiles are very similar to flat tiles, with one obvious difference, in that they have holes through which an oak peg is pushed through, holding the tiles together. The roof can be very colourful, as moss growths can occur, and tiles when replaced will often be a different shade to the majority of the roof. Modern day pegs tend to be made from steel or aluminium rather than oak.

Thatched Roofing
Thatching is the art of covering a roof with vegetation such as straw or rushes. It is one of the oldest roofing materials, and has been used worldwide. It is still employed in a number of third-world countries, as well as in a number of Western European homes. However, thatching is no longer a low cost method of roofing, as costs have increased considerably over the previous 40 years.
Thatching is a high quality material, and if installed by a skilled thatcher, can last over 50 years, though this is subject to the material used, as certain types are better suited to specific climates. Traditionally, a new layer of thatching was applied over the existing layers, which has left some old thatched buildings with thatched roofs over 2 metres thick!
The obvious danger of a thatched roof is that of fire. Thatched roofs do not catch fire and more frequently than normal roofs, however the risk is that once alight it can be very difficult to put out. If the chimney of a thatched house is of poor quality, and gases or sparks escape into the roofing then fire does become a greater risk. As a result, many insurers won't insure a thatched home, and the few that do will charge high premiums, as they are aware that buyers have no choice.
Thatched roofs are coming back into fashion at the moment, as an environmentally friendly, and sustainable, material.
Thatched roofs are banned in the City of London, since the Great Fire of London in 1666. The law remains in place today, and there is only one exception to the rule the replica of the Globe theatre.

Felt Roof
Felt roofs are made from a rigid urethane or phenolic insulant, which is laminated onto a solid roofboard.
A felt roof is applied to a baseboard, which is coated with a preservative. This is to help maintain the condition of the baseboard for longer. Lay the felt roofing over the baseboard and secure it using clout nails, ensuring the material is laid smoothly, with no air bubbles. Over the first layer, paint bitumen mastic over the layer before applying the felt layer flat. Using a soft brush, try to remove any air bubbles. Depending on the strength of the roof, you may be able to walk on any air bubbles to remove them. Any gaps should be painted with bitumen mastic to aid waterproofing. Finally, apply the third layer in the same way as the second. Apply another coating of bitumen mastic over the entire surface, before scattering a chipping compound of limestone, granite or gravel, across the roof. This helps strengthen the surface, and also helps to reflect sunlight, protecting the roof.
Felt roofing is usually used for flat roofs. Many homes can have certain areas with a flat roof which requires felt roofing, as tiles are not effective on a level surface. Garages and pre-fabricated buildings regularly use felt roofing as it is cheaper and easier to apply then tiling. It is also common on garden sheds, due to the light weight construction used.

Corrugated Iron
This is a cheap method of roofing, used mainly in military installations and farm outbuildings due to its low cost and strength. Corrugated Iron can also be transported easily, due to its regular shape.
Some houses do use corrugated iron in their construction, typically more remote homes in Australia and the United States, with a number of developing countries beginning to use it in construction as it is cheap and easily obtainable.