Not every roofing material can be used on every roof. The IRCA members offer valuable planning and material recommendations for your roofing project.
Commercially available roofing material
The weatherproofing material is the topmost or outermost layer, exposed to the weather. Many materials have been used as weatherproofing material.
Membrane roofing is in large sheets, generally fused in some way at the joints to form a continuous surface.
- Thermoset membrane (e.g. EPDM rubber). Synthetic rubber sheets adhered together with contact adhesive or tape. Primary application is big box stores with large open areas.
- Thermoplastics (e.g. PVC, TPO, CSPE) – Plastic sheets welded together with hot air, creating one continuous sheet membrane. They can be re-welded with the exception of CSPE. Lends itself well to both big box and small roof application because of its hot air weldability. This membrane is installed by two methods: 1.) Rolls of membrane are attached to the ridged insulation using a bonding adhesive; 2.) The edge of each roll is fastened through ridged insulation into structural deck, and the proceeding roll is lapped over the fasteners. The overlap is then heat-welded with hot air to create a mechanically fastened thermoplastic roof. SeeVinyl roof membrane.
- Liquid roofing
- Asphalt roll roofing including single and double coverage types.
- Bituminous waterproofing is a general term for:
- 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 most applications.
- Built-up roof – Multiple plies of salt-saturated organic felt or coated fiberglass felts. Plies of felt are adhered with hot asphalt, coal tar pitch or adhesive. Although the roof membrane can be left bare, it is typically covered with a thick coat of the waterproofing material and covered with gravel. The gravel provides protection from ultra-violet degradation, stabilizes the temperature changes, protects surface of the roof and increases the weight of the roof system to resist wind blow-off.
- PTFE, (synthetic fluoropolymer) embedded in fibreglass.
- Corrugated galvanised iron is Galvanised steel manufactured with wavy corrugations to resist lateral flexing and fitted with exposed fasteners. Widely used for low cost and durability. Sheds are normally roofed with this material. Gal iron or Corro was the most extensively used roofing material of 20th century Australia, now replaced in popularity by steel with longer-lasting, coloured, alloy coatings.
- Copper roofs can last for hundreds of years. Copper roofing offers durability, ease of fabrication, lighter weight than some other roofing materials, can be curved, low maintenance, corrosion resistance, low thermal movement, lightning protection, radio frequency shielding, and are 100% recyclable. Copper roofs have a high initial cost but very long lifetime: tests on European copper roofs from the 18th Century showed that, in theory, copper roofs can last one thousand years. Another advantage of copper roofing systems is that they are relatively easy to repair.
- Standing-seam metal with concealed fasteners.
- Mechanically seamed metal with concealed fasteners contains sealant in seams for use on very low sloped roofs, suitable for roofs of low pitch such as 0.5/12 to 3/12 pitch.
- Flat-seam metal with or without soldered seams.
- Steel coated with a coloured alloy of zinc and aluminium.
Shingle is the generic term for a roofing material that is in many overlapping sections, regardless of the nature of the material.
- Wood shingle, shingles sawn from bolts of wood such as red cedar which has a life expectancy of up to 30 years. However, young growth red cedar has a short life expectancy and high cost. Also in the eastern United States white cedar and some hardwoods which were very durable roofing found in Colonial Australian andAmerican colonial architecture, its use is now limited to building restoration. All wood shingles benefit by being allowed to breathe (dry out from below).
- Shake (shingle), shingles split from bolts of wood which generally gives a rougher appearance.
- Slate. High cost with a life expectancy of 80 to 400 years. See the article slate industry for an overview including names of quarries. Some of the famous quarries where the highest quality slate comes from that are available in Australia are Bethesda in Wales and areas of Spain.
- Asphalt shingle, made of bitumen embedded in an organic or fiberglass mat, usually covered with colored, man-made ceramic grit. Cheaper than slate or tiles. The cheapness of this particular style of roofing is its of application and removal. The installation is a very streamlined and rapid process. Depending on the size of the roof, and the experience of the crew, it is possible to remove the old shingles and apply the new, on 2-3 houses in one day. Various life span expediencies.
- Rubber shingle, alternative to asphalt shingle, slate, shake or tile. Made primarily of rubber, often recycled tire-derived rubber. Other typical ingredients include binders, UV (ultraviolet light) inhibitors and color. Warranted and designed to last at least 50 years in most cases.
- Asbestos shingles. Very long lifespan, fireproof and low cost but now rarely used because of health concerns.
- Stone slab. Heavy stone slabs (not to be confused with slate) 1–2 inches thick were formerly used as roofing tiles in some regions in England, the Alps, andScandinavia. Stone slabs require a very heavyweight roof structure, but their weight makes them stormproof. An obsolete roofing material, now used commercially only for building restoration.
- Collyweston stone slate
- Solar shingle
- Metal shakes or shingles. Long life. High cost, suitable for roofs of 3/12 pitch or greater. Because of the flexibility of metal, they can be manufactured to lock together, giving durability and reducing assembly time. For a discussion of copper system shingles, see Copper in architecture#Wall cladding.
Stone-coated metal roofing
- Concrete or fibre cement, usually reinforced with fibres of some sort.
- Structural concrete can also be used for flat roof constructions. There are three main categories, precast/prestressed, cast-in-place and shell. There are many types of precast/prestressed concrete roofing. The followings are the most common types.
High cost, life of more than 100 years.
- Imbrex and tegula, style dating back to ancient Greece and Rome.
- Monk and Nun, a style similar to Imbrex and tegula, but basically using two Imbrex tiles.
- Dutch roof tiles, Netherlands
- British Ceramic Tile, United Kingdom
- Mangalore tiles, India
Residential Roofing Options
Not every roofing material can be used on every roof. A flat roof or one with a low slope may demand a surface different from one with a steeper pitch. Materials like slate and tile are very heavy, so the structure of many homes is inadequate to carry the load.
This is the most commonly used of all roof materials, probably because it’s the least expensive and requires a minimum of skill to install. It’s made of a fiberglass medium that’s been impregnated with asphalt and then given a surface of sand-like granules. Two basic configurations are sold: the standard single-thickness variety and thicker, laminated products. The standard type costs roughly half as much, but laminated shingles have an appealing textured appearance and last roughly half as long (typically 25 years or more, versus 15 years plus). Prices begin at about $50 a square, but depending upon the type of shingle chosen and the installation, can cost many times that.
Aluminum, steel, copper, copper-and-asphalt, and lead are all durable—and expensive—roofing surfaces. Lead and the copper/asphalt varieties are typically installed as shingles, but others are manufactured for seamed roofs consisting of vertical lengths of metal that are joined with solder. These roofs start at about $250 per square but often cost two or three times that.
Tile and Cement
The half cylinders of tile roofing are common on Spanish Colonial and Mission styles; cement and some metal roofs imitate tile’s wavy effect. All are expensive, very durable, and tend to be very heavy.
Slate is among the most durable of all roofing materials. Not all slate is the same—some comes from quarries in Vermont, some from Pennsylvania and other states—but the best of it will outlast the fasteners that hold it in place. Hundred-year-old slate, in fact, is often recycled for reinstallation, with the expectation it will last another century. But slate is expensive—typically prices start at about $800 a square—and very heavy.
Wood was the main choice for centuries, and it’s still a good option, though in some areas fire codes forbid its use. Usually made of cedar, redwood, or southern pine, shingles are sawn or split. They have a life expectancy in the 25-year range (like asphalt shingles) but cost an average of twice as much.