The weather proofing material is the topmost or outermost layer, exposed to the weather. Many different kinds of materials have been used as weather proofing material:

• Shingles - are a roof covering consisting of individual overlapping elements. These elements are normally flat rectangular shapes that are laid in rows without the side edges overlapping, a double layer is used to ensure a waterproof result. Shingles are laid from the bottom edge of the roof up, with the bottom edge of each row overlapping the previous row by about half its length. At the roof ridge there was a cap consisting of copper or lead sheeting which has been substituted by shingles with a PVC underlay.
  Shingles have been made of various materials such as wood shingle, slate shingle, asbestos-cement, bitumen-soaked paper covered with aggregate (asphalt shingle) or ceramic. Due to increased fire hazard, wood shingles and paper-based asphalt shingles have become less common than fiberglass-based asphalt shingles. In the United States, fiberglass-based asphalt shingles are by far the most common roofing material used for residential roofing applications.
  
• Slate - Slate can be made into roofing slates, also called roofing shingles, installed by a slater. Slate has two lines of breakability: cleavage and grain. This makes it possible to split slate into thin sheets.
  
• Ceramic Tile - Roof tiles are designed mainly to keep out rain, and are traditionally made from locally available materials such as clay or slate. Modern materials such as concrete and plastic are also used and some clay tiles have a waterproof glaze.

  A large number of shapes (or "profiles") of roof tiles have evolved. These include:

  • Flat tiles - the simplest type, which are laid in regular overlapping rows. This profile is suitable for stone and wooden tiles, and most recently, solar cells.
  • Imbrex and tegula, an ancient Roman pattern of curved and flat tiles that make rain channels on a roof
  • Roman tiles - flat in the middle, with a concave curve at one end at a convex curve at the other, to allow interlocking.
  • Pantiles - with an S-shaped profile, allowing adjacent tiles to interlock. These result in a ridged pattern resembling a ploughed field.
  • Mission or barrel tiles are semi-cylindrical tiles made by forming clay around a curved surface, often a log or one's thigh, and laid in alternating columns of convex and concave tiles.

  Roof tiles are 'hung' from the framework of a roof by fixing them with nails. The tiles are usually hung in parallel rows, with each row overlapping the row below it to exclude rainwater and to cover the nails that hold the row below.

  There are also roof tiles for special positions, particularly where the planes of the several pitches meet. They include ridge, hip and valley tiles.
  

• Cement - In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. The name "cement" goes back to the Romans who used the term "opus caementitium" to describe masonry which resembled concrete and was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives which were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment and cement. Cements used in construction are characterized as hydraulic or non-hydraulic.
  
• Asphalt shingle - Two types of asphalt shingles are used: organic and fiberglass or glass fiber. Organic shingles are generally paper (felt) saturated with asphalt to make it waterproof, then a top coating of adhesive asphalt is applied and the ceramic granules are then embedded. A portion of the granules contain leachable copper or more often tin to prevent moss growth on the roof. Organic shingles contain around 40% more asphalt per square (100 sq. ft.) than fiberglass shingles which makes them weigh more and gives them excellent durability and blow-off resistance. Shingles are judged by weight per square.
  Fiberglass shingles have a glass fiber reinforcing mat manufactured to the shape of the shingle. The mat is then coated with asphalt which contains mineral fillers. The glass fiber mat is not waterproof by itself and is a wet laid fiberglass mat bonded with urea-formaldehyde resin. It's used for reinforcement. The asphalt makes the fiberglass shingle waterproof. Fiberglass reinforcement was devised as the replacement for asbestos paper reinforcement of roofing shingles and typically ranges from 1.8 to 2.3 pounds/square foot. The older asbestos versions were actually more durable and were harder to tear, an important property when considering wind lift of shingles in heavy storms. Fiberglass is slowly replacing felt reinforcement in Canada and has replaced mostly all in the United States. Widespread hurricane damage in Florida during the 1990's prompted the industry to adhere to a 1700 gram tear value on finished asphalt shingles.
  Shingles are ranked by waranteed life, ranging from 25 to 50 years. A newer design of asphalt shingle, called laminated, uses two distinct layers and is heavier, more expensive and more durable than traditional designs. Laminated shingles also give a more 3-D effect to a roof surface.
  
• Asbestos shingles - Very long lifespan, fireproof, low cost but now rarely used because of health concerns.
  
• Thermosetting plastic - Synthetic rubber sheets adhered together with contact adhesive or tape. Primary application is big box store with large open areas and little vertical protrusions. Relies heavily on the skill of the applicator. Detail critical.
  
• Thermoplastic - Plastic sheets welded together with hot air. Can be rewelded with the exception of CSPE. Lends itself well to both big box and small roof application because of its hot air weldability. Relies heavily on the skill of the applicator. Detail critical.
  
• Modified bitumen - heat welded, asphalt adhered or installed with adhesive. Asphalt is mixed with polymers such as APP or SBS, then applied to fiberglass and/or polyester mat, seams sealed by locally melting the asphalt with heat, hot mopping of asphalt, or adhesive. Lends itself well to all applications. Requires some training.
  
• Built-Up Roof - A Built Up Roof (BUR), generally consists of two or more layers of roofing felts laminated together using hot or cold asphalt or hot coal tar pitch as an adhesive. Built Up - meaning to "build" upon each other - The layered materials which are referred to as "plies" and are often covered with a heavy coating of asphalt or tar into which a layer of gravel is spread. The gravel surface serves several purposes; Protection from the Sun's UV rays and protection from damage caused by roof traffic are the two most important benefits. Built up roofs are desirable when heavy roof traffic or spilled contaminants are to be expected.
  
• Sprayed-in-Place Polyurethane Foam (SPUF) - Foam sprayed in-place on the roof, then coated with a wide variety of coatings, or in some instances, covered with gravel.
  
• Metal roofing - Usually lasts about twice as long as an asphalt roof. Tends to reflect more heat away (saving energy in the summer in southern climates). Resistant to damage from hail, branches, wind and forest fires. Lightweight so less roof sag. Brighter smoother colors. Rainwater harvesting systems may use metal roofs in order to limit contamination of water that has flowed over it. Not stocked in stores as much as asphalt shingle products. Can be more slippery because of smooth surface.

  • Galvanized steel - A strong, common and inexpensive metal roofing. Comes in different grades. Best grade has a zinc/aluminum galvanized layer to protect the steel. Will rust far quicker than aluminum in most situations. But more resistant to other types of damage. And will still last probably at LEAST 25 or 30 years. Compared to asphalt shingles which often last only half of their rating ( a 40 year asphalt shingle will need replacement in about 20 years).
  • Aluminum - One of the longest lasting metals, but somewhat expensive.
  • Copper - Usually used for flashing or very small sections like covered entryways. Expensive.
  • Cool Metal Roofing - Painted, finished metal roofing that is energy-efficient due to relative emissivity and reflectivity.
• Roofing Felt - a fiberglass or polyester fleece impregnated with bituminous impregnating agents (tar, asphaltic bitumen); it is produced in roll form. In some cases mineral materials (e.g. sand) is applied on one side to help prevent the material from sticking together while in roll form and to provide protection from atmospheric conditions. A distinction is drawn between tarred board and bitumen board.
  Roofing felt is used, among other things, for waterproofing roofs to prevent ingress of moisture.
  It can be installed in several ways including but not limited to: mechanical fasteners, hot asphalt, cold asphalt (adhesive), non-asphaltic adhesives, and heat (torch, hot air) or a combination of the afore mentioned.
  Many new pitched roofs however use a new form of waterproof membrane. These membranes (which are usually made up of advanced fabrics)have many advantages over traditional 1F roofing felt, in that they are a lot more durable and less prone to puncture and tear. They are also incredibly lightweight, though this can be disadvantageous when trying to install in even the lightest of wind. This felt also comes in the breathable variation, which allows moisture to pass through the felt which, when used in conjunction with proper ventilation, helps minimize condensation in loft spaces.
  
• Thatch -is the craft of covering a roof with vegetation such as straw, water reed, sedge, rushes and heather. It is probably the oldest roofing material and has been used in both tropical and temperate climates. Thatch is still employed by builders in developing countries, usually with low-cost, local vegetation. By contrast in some developed countries it is now the choice of well-to-do people who want their home to have a rustic look.
  Thatch is a competitive thermal insulator when applied thickly. A thatched roof will ensure that a building will be cool in summer and warm in winter. Local techniques, such as the placement of a turf substratum by the Scottish, can reduce air movement and improve insulation even further.
  Thatch is a versatile material when it comes to covering irregular roof structures. This fact lends itself to the use of second-hand, recycled and natural materials that are not only more sustainable, but need not fit exact standard dimensions to perform well.
  Thatching is sustainable If crops are managed ecologically, than the resource can be renewed regularly. Many of the natural thatching materials are improved by regular harvesting. For example, reeds, marram grass, broom, heather, and juniper all regrow in more usable forms. Thatch can be recycled to be an excellent fertilizer.
  Thatch is beautiful. As local materials always tend to harmonize with the landscape surrounding their place of origin, thatch, as a natural material, will always blend well with a rural environment. Thatch has an ecological advantage because, it is produced by natural processes that do not use scarce and expensive resources of energy.
  Thatched houses are more vulnerable to fire risk than those covered with other materials, and it is therefore imperative that precautions be taken to reduce the risk. Insurance costs can be higher due to this factor. The process of thatching is more labor intensive than other methods of roofing, affecting the overall cost.
  Being an organic material, thatch is susceptible to decay and decomposition and precautions must be taken to minimize the possibility of this process taking place. In warm, wet climates thatch is prone to fungal attacks.Animals can cause damage. Birds looking for food, gathering nest-making materials or nesting in the roof itself becomes a greater possibility when the plant material is not processed appropriately for its intended use. Rodents can cause extensive damage when present in the house. The quality of design and building can greatly effect the performance of the roof. If built and/or maintained inadequately, then problems such as vulnerability to wind damage and prolonged damp conditions are issues.
  Thatch can be maintenance intensive. The maintenance cycle varies based on thatch type, roof pitch, the degree of shade or exposure and the kinds of materials used.
  
• Tar Paper - is a heavy-duty paper used in construction. Roofing felt is one type of tar paper. Tar paper is made by impregnating paper with tar, producing a waterproof material useful for roof construction. It is sold in rolls of various widths, lengths, and thicknesses (3 foot wide rolls, 50 or 100 feet long and "15 lb" and "30 lb" weights are common in the U.S.), often marked with chalk lines at certain intervals to aid in laying it out straight on roofs with the proper overlap (more overlap for flatter roofs). This bitumen based material is sometimes applied in several layers with the help of a torch and additional hot tar, but is more often applied with staples or roofing nails and used as underlayment for asphalt, wood (a.k.a. shake), or other shingles, or even gravel, since tar paper itself isn't particularly wind- or sun-resistant. More modern roof waterproofing materials include PVC and TPO (thermoplastic polyolefine) membranes which provide increased protection against leaks.
  Older construction sometimes used a lighter weight tar paper, stapled up with some overlap, as a water- and wind-proofing material, but modern construction uses 8 or 10 foot widths of "Housewrap," one brand of which is Tyvek, which is extremely durable and wind- and water-proof since there are far fewer seams than with the 3 foot wide rolls of tar paper.
  
• Solar Roof - Newer systems include solar shingles which generate electricity as well as cover the roof. There are also solar systems available that generate hot water or hot air and which can also act as a roof covering. More complex systems may carry out all of these functions: generate electricity, recover thermal energy, and also act as a roof covering.
  There are different ways that solar systems can be integrated with roofs:

  • integrated in the covering of pitched roofs, e.g. solar shingles.
  • mounted on an existing roof, e.g. solar panel on a tile roof.
  • integrated in a flat roof, e.g. PVC.
  • mounted on a flat roof with a construction and additional weight to prevent uplift from wind.