Info about Roofing

While roofs have been part of construction for ages, many of us do not necessarily know the first thing about roofing, or the second, or the third...

Here is a little bit of general information about roofing.

(According to Roofing101.com)

Residential Roofing - Installation, Replacement and Repair

Roofing Basics for every Homeowner 

Installing a roof is one of the most critical aspects of building a home.  
This website strives to provide readers with comprehensive information to help new homeowners choose a roof.  

We give details of the most commonly used roof styles and materials, their benefits and disadvantages, and various methods of installation.  

We highlight the type of damage roofs typically sustain and provide advice to help the homeowner decide whether repair or replacement is necessary to correct damage.

Choosing a New Roof

Installing the roof is one of the most  critical aspects of building a home. Most homeowners want a roof that  looks good, is long lasting and requires little maintenance, and falls  within their budget.  

Roofs that are not installed professionally may  provide inadequate insulation for the home or poor protection from the  elements. Without adequate maintenance a roof may require frequent  repairs, and a shorter lifespan means replacement every 10 to 15 years.  

Professional installation of the right style of roof using suitable  materials can save the homeowner a substantial amount in repair and  maintenance costs, create a lower environmental impact and place less of  a demand on energy and natural resources.

Selecting the right roof for a new or renovated home depends on a number of factors:  

The most important factors are the budget available for the roof and the size of the roof area.  
  • Take measurements of the roof and obtain estimates from local contractors based on their recommendations.
  • Ask for quotes on the different types of roofing materials and styles.
  • Research the local climate, as weather conditions can significantly affect the choice of roofing material.
  • Calculate the slope of roof needed by dividing the length of the rise (vertical distance) by the length of the run (horizontal distance). The degree of slope will help determine the most suitable roofing style and type of material.
Roofing Styles

The most common roofing styles for residential homes are the gable, hip, A-frame and flat roof styles. Each style has benefits and disadvantages for the homeowner, and the choice of style must be a factor in selecting the type of roofing material.

Gables and Hips

Gable roofs and hip roofs are the most common roof shapes in the U.S., and both can be built with either a low or a steep pitch. They can be adapted to a range of house shapes and designs, shrug off water and snow well, provide for adequate attic ventilation, and are convenient for installing insulation. The gable is a two-sided roof that slopes down from the main ridge of the building, while a hip roof has four slopes running downwards from the center and side ridges.

A-Frame

The A-frame roof is a steep roof, with two sides that slope down from the center ridge almost to the ground, serving as the upper walls of the home as well as the roof. Based on the Native American “teepee” design, these roofs are found on homes built in the 1960s. Advantages of the A-frame include substantial space for insulation and storage within the upper reaches, as well as easy snow removal. However, this style of roof requires a large quantity of roofing materials and is therefore expensive, and it creates dead space at the corners of each floor level.

Flat Roofs

Flat roofs are economical and do not require much roofing material. They should be pitched slightly to aid drainage and can be adequately waterproofed using built-up layers of roofing, felt, and tar topped with gravel. Homes with flat roofs are commonly found in warmer parts of the country, where their wider overhangs provide shade for the rooms. They are not practical in snowy climates, due to the difficulty of snow removal, and do not allow much space for insulation or heat deflection.

Take-aways

The gable roof is the most basic design and the most practical. It is the least expensive and has few disadvantages compared with the other roof styles. Hips add to the attractiveness, but they also create corners and hollows where leaks can develop. A-frame roofs are expensive but stylish, and flat roofs are frequently impractical.

Choosing a Roofing Contractor

Selecting a professional roofing contractor is important for ensuring quality work that is supported by reliable after-sales service. Follow these steps to find a contractor who complies with the requirements for a hassle-free installation.

Research

Search for contractors who have experience with the local conditions, and short-list three of the companies that seem promising. Interview a representative from each company, and ask questions about the work that the company has done in the area. Determine whether the company has an office in the vicinity, and ask for the full address. Professional contractors are more likely to have business premises instead of working from home; if the office is nearby, the contractor’s response time will be shorter in case of an emergency.

Legal Requirements

Research the requirements for professional licensing, and verify that the contractor is licensed to operate in the state. Some states require contractors to pass examinations as evidence of their qualifications. Find out how long the company has been operating and ask about the warranties available on their work. The contractor should offer a warranty on the workmanship, and the roofing materials should be covered by a manufacturer’s warranty. The manufacturer’s warranty may be valid only if the roof is installed by an authorized contractor. Obtain a hard copy of each of the two documents, and keep them safe for the duration of the warranties.

Insurance

Check whether the company has liability and workers’ compensation insurance. The first ensures that the homeowner is not personally liable for accidental damage to the house. The second protects the homeowner from liability if a worker is injured while working on the property. Ask to see written proof of insurance, and don’t be tempted to accept a lower price from an uninsured contractor.

Referrals

Ask each company for a list of former customers to request referrals. Contact each homeowner personally, and ask whether the work was performed on time and within the budget. Ask about the contractor’s attitude, whether the company operated professionally and if the referrer would recommend the company. Find out if the contractor responded positively and promptly to any after-sales services that were required.

The Contract

Check that all details of the agreement are included in the contract, and verify whether costs such as permit requirements are covered. To avoid being sold an inferior-quality roof, ensure that the contract specifies the brand or type of roofing. List the exact start and end dates, and include penalties for late completion. The contract should also contain a breakdown of costs and a payment schedule, as well as details of insurance and warranties, and it should identify responsibility for clean-up work and costs.

Take-aways

Finding the right contractor to install a roof is as important as choosing the roof style and material. The homeowner needs to be sure that the contractor is operating legally, is insured, and has the means and intention to provide any necessary after-sales services. To avoid misunderstandings, the contract should list every detail of the work, dates and payments.

Installing a New Roof

Maintaining a roof means cleaning it regularly, conducting biannual inspections and ensuring that necessary repairs are performed as soon as possible. Preventative maintenance can stop small, easy-to-fix problems from becoming costly repairs, will prolong the roof’s life span and will add to the home’s investment value.

Cleaning

A dirty roof is unsightly and can reduce the home’s curb appeal and resale value. Moss, algae and mold grow regularly on roof tiles and discolor them; bird droppings, mud and dust will also accumulate. Roofs should be cleaned annually, either by a professional contractor or as part of the maintenance program.
For a DIY clean, use a solution of 50 percent water, 40 percent bleach and 10 percent general purpose household cleaner. Apply the solution using a low-pressure garden sprayer. Leave it for 20 minutes to soak off the dirt before rinsing the roof with clean water. Never use a high-pressure spray to wash the roof, as this can dislodge shingles and cause damage similar to severe weather.

Inspections

Regular roof inspections allow the homeowner to identify potential problems before they become more serious. Inspections should take place at least twice annually, during the spring and the fall, and should include:
  • Checking the interior and exterior of the roof for signs of moisture, worn spots, deterioration or aging of the sealant, changes in insulation quality and substrate firmness;
  • Checking flashing for any loose attachments, missing fasteners, moisture and corrosion, cracked or aging sealant;
  • Checking the roof penetration areas, such as pipes and other items inserted through the roof membrane, for the integrity of the seal around the entry point.

Maintenance Programs

A comprehensive maintenance program provides for two to four scheduled roof inspections each year, in return for one annual payment or a monthly premium. Some programs provide for ad hoc inspections after extreme weather events, while others offer these inspections at an additional cost. Debris removal may be included in the maintenance agreement, because it will be impossible to inspect the roof while debris is present. The contract may include cleaning and minor repairs, or the homeowner may receive a cost estimate for the repairs after the inspection.

Take-aways

Scheduled maintenance and cleaning can preserve the roof and extend its life span, and they help homeowners save money through the early detection of problems. Maintenance programs are a cost-effective method of ensuring that inspections and cleaning take place regularly.

Roof Maintenance

Maintaining a roof means cleaning it regularly, conducting bi-annual inspections and ensuring that repairs needed are performed as soon as possible. Preventative maintenance can stop small, easy-to-fix problems from becoming costly repairs, prolong the roof’s lifespan and add to the home’s investment value.

Cleaning

Moss, algae and mold are culprits that grow regularly on roof tiles and discolor them. Bird droppings, mud and dust accumulate, and a dirty roof is unsightly and can reduce the home’s curb appeal and resale value. Roofs should be cleaned annually, either by a professional contractor or as part of the maintenance program.
For a DIY clean, use a solution of 50 percent water, 40 percent bleach and 10 percent general purpose household cleaner. Apply the solution using a low-pressure garden sprayer. Leave for 20 minutes to soak off the dirt before rinsing with clean water. Never use a high-pressure spray to wash the roof, as this can dislodge shingles and cause damage similar to severe weather.

Inspections

Regular roof inspections can enable the homeowner to identify potential problems before they become worse. Inspections should take place at least twice annually during the Spring and the Fall, and should include:
  • Checking the interior and exterior of the roof for signs of moisture, worn spots, deterioration or aging of sealant, changes in insulation quality and firmness of the substrate;
  • Checking flashing for any loose attachments, missing fasteners, moisture and corrosion, cracks or aging sealant;
  • Checking the roof penetration areas, such as pipes and other items inserted through the roof membrane, for integrity of the seal around the entry point.

Maintenance Programs

A comprehensive maintenance program provides for two to four scheduled roof inspections each year, in return for one annual payment or a monthly premium. Some programs provide for ad hoc inspections after extreme weather events, while others offer these at an additional cost. Removal of debris may be included in the maintenance agreement, because it will be impossible to inspect the roof while debris is present. The contract may include cleaning and minor repairs, or the homeowner may receive a cost estimate for the repairs after the inspection.

Take-aways

Scheduled maintenance and cleaning can preserve the roof and extend its lifespan, and help save money by early detection of problems. Maintenance programs are a cost-effective method of ensuring that inspections and cleaning take place regularly.

Roof Damage

The type of damage a roof sustains is typically caused by moisture or weather. Seasonal changes play a role in the deterioration of roofing materials, and the roof begins aging immediately after it is installed.

Water Damage

Water damage is the most common cause of roof problems. Research has shown that an inadequately ventilated roof area prevents air movement, which increases the moisture content in the air. Moisture causes corrosion, deterioration of insulation materials, and expansion and contraction of the wooden support structure, which impairs the performance of shingles or other roofing materials. The resulting gaps cause the roof to leak, which results in more damage.

Weather Damage and Fatigue

Extreme weather incidents such as severe storms, high winds and heavy rain can dislodge shingles, but even everyday weather has a negative effect on a roof. Summer sunshine reflected off the roof can cause the roof’s temperature to rise, and the arrival of a cold front or a thunderstorm causes it to drop rapidly. The shock of such expansion and contraction places a strain on the support structure as well as the cladding, causing fatigue and deterioration.

Take-aways

Most roof damage is caused by either moisture or weather fatigue. Early detection and prompt repairs are essential to prevent problems from becoming worse and to avoid the costly replacement of insulation materials and decking.

Roof Repairs


A roof is in use from the moment it is installed. Subjected to sun, wind, rain, hail and snow, the roofing materials begin to deteriorate immediately, and rafters and trusses show evidence of wear and tear. The most common roof problem in the U.S. is water damage, either in the form of a leaky section of roof, or in the mold and damp that develop as a result of moisture within the roof cavity.
Repairs should never be postponed, and biannual roof inspections help the homeowner ensure that problems are not aggravated by lack of attention. For homeowners without a roof maintenance program, some roofing contractors will conduct an inspection at no cost, followed by a report and a free, no-obligation quotation for the necessary repairs. Repairs may simply entail replacing a few shingles or a section of metal, or the roofing contractor might recommend a full roof replacement.

Repairing Shingle Roofs

Roofs occasionally develop leaks caused by cracked or missing shingles or shakes, or a blistered and cracked section of a flat roof. Often, the best way to identify a leak in the roof is from water damage on the internal walls. Shingle roofs are simple to repair; first, locate the leak, then isolate the source by marking the damaged, curled or missing shingles, and then replace them. If the leak is close to a joint such as a chimney, breaks in the caulking or flashing may be the culprit. Shingles that are lifting or curling can easily be reattached in warm weather with asphalt roof cement or compound; in cold weather, the shingle must be warmed and softened using a propane torch flame, then straightened before reattaching it.
Shingles that are torn, rotten or missing must be replaced. If an area of roof shows signs of rot, it may be necessary to replace the entire section. Damaged shingles need to be removed carefully, and loose or brittle cement must be scraped out. Protruding nails should be removed, and new shingles should be placed carefully and aligned with the adjacent shingles. Overlapping corners should be fastened into place on top of the new shingles, and any remaining gaps should be filled with caulking or spray foam insulation material.

Repairing Flat and Shake Roofs

To repair a blistered flat roof, the blistered area needs to be cut out, cleaned and dried thoroughly before recoating with roofing cement, tar and gravel. Wooden shake roofs are more complex: the wooden shingles are split using a hammer and a sharp chisel and then removed. The heads of the nails holding the shakes in place may need to be cut down if they cannot be removed, and a new shake must be cut to match the roofing materials. In all cases, the wooden supports should be examined to ensure that there is no water damage within the roof cavity.

Repairing Metal Roofs

A metal roof can be repaired by cleaning and removing the damaged section of metal and covering the area with a section of metal large enough to overlap the hole. Butyl tape or another sealant is inserted under the edges of the new section, which is fasted with metal screws. The edges and screws are sealed with caulking, and a roof membrane may be added to ensure that the whole roof remains waterproof.

Take-aways

Most roof repairs occur as a result of water or weather damage. It is critical to conduct regular roof inspections and to repair any problems as soon as they are identified. Repair work should be thorough, using quality materials designed to withstand weather and moisture for the life span of the original roof.

Replacing a Roof

Roof replacement or remodeling occurs when the damage is too great to repair a section of the roof, the roofing materials are old or outdated, or the homeowner decides to renovate the building. Methods of re-roofing include the “tear-off” and “lay over” methods, and the choice of method depends on the roofing material used originally, the condition of the old roof, the accessibility of the existing roof’s interior and the extent of the damage. In some jurisdictions, roof replacement requires a permit similar to that needed for installing a roof on a new home. Building codes in certain states allow only a single lay-over to be conducted, although for practical purposes a lay-over can be done up to three times.

Tear-Off Method

Depending on the roofing material used, it may not be feasible to lay new shingles over the old. While this is usually the less expensive route, it is not necessarily the best decision. In the tear-off process, the old roof is removed in its entirety. This enables the roofing contractor to examine the inner section of the roof and evaluate the condition of the trusses or rafters. He can also make any necessary flashing repairs and identify condensation or other moisture problems in the attic. For homeowners who select a long-lasting roofing material such as metal, this process provides the opportunity to install new waterproofing underlayment to protect against future leaks, and it allows the contractor to correct any ventilation problems that may result from an old, inferior roof.

Lay-Over Method

This process is best used when a roof is being replaced or remodeled for mainly aesthetic purposes. Provided that the original roof is intact or needs only minor repairs, the wooden supports pass inspection for rot and moisture, and they are deemed strong enough to support the additional weight, a new roofing material may be laid over the old. If the lay-over process is selected,  it is advisable to install a full underlayment over the old roof before adding the new, or existing damage such as rot and moisture could spread to the new roof. During a lay-over installation of a new metal roof, lightweight metal may require wooden boards to be laid over the old roof before attaching the new roof. This is usually performed to even out the appearance of the old roof and to prevent an uneven surface once the new metal roof is in place.

Take-aways

While the lay-over method of replacing a roof is acceptable, it is not always the wisest choice. It may also be subject to building codes, so the homeowner should carefully evaluate the practical aspects of using this method. For a long-lasting roof, the tear-off process is frequently a better prospect.

(According to HomeTips.com)

Roofing Construction Basics

House roof framing and construction diagrams, with important roofing terms, roof shapes and framing types.

Carpenter uses a pneumatic nailer to attach plywood sheathing to the roof rafters—in this case, a series of roof trusses.
Roofs take quite a beating. Fully faced toward the sky, they catch the brunt of weather’s worst. They have to be able to take a licking and keep from leaking. They must be weathertight, secure, durable, attractive, and elastic enough to withstand severe temperature shifts without cracking.

Over the centuries, roof-building techniques have been refined to yield roofs of considerable strength and durability. A wide variety of materials has been developed that will last many years—in some cases, as long as the house. And homeowners have a vast selection of materials, colors, prices, and other features from which to choose.

A contemporary roof, regardless of shape or surface material, consists of a variety of components that include wood framing, sheathing, underlayment, flashing, gutters, and, of course, the shingles or other finished surface. The illustration here shows how these materials go together to make for a sound roof.


The roof deck is made up of sheathing and, in most cases, underlayment, which is called roofing felt.

The type of deck used depends on the finished roofing material. Most call for solid plywood or oriented-strand-board (OSB) panel sheathing; wood shingles and some tile or metal roofs call for spaced-board sheathing.

Roofing felt is sandwiched between the sheathing and the surface material on most roofs. This heavy, fibrous black paper saturated with asphalt helps repel any water that might find its way past the roofing material.

Flashing helps repel water wherever the roof surface is broken by dormers, intersecting roof planes, and protrusions, as well as along the roof’s edges. Flashing is traditionally made from galvanized steel, aluminum, or vinyl.

How Roof Flashing Works

Some parts of roofs and exterior walls are particularly prone to leaks and water damage. These include roof valleys, the intersection between a dormer wall and the roof surface, and chimney and skylight perimeters—nearly anywhere runoff is heavy or where two opposing surfaces meet. These areas require the extra protection that flashing provides.

Although roof flashing is occasionally fabricated from plastic, roofing felt, or rubber, it is usually made of rust- resistant metal—galvanized steel, aluminum, or copper. Galvanized sheet metal is most common, but aluminum and copper find occasional use in specialty situations. Aluminum flashing is very popular for do-it-yourself installation because it’s easy to bend. Copper flashing is usually custom fabricated for use with copper roofs.
Flashing is formed and, in some cases, soldered into various shapes, depending upon the job it must do. Following are the main types of roof flashing:


Chimney flashing is applied around the base of a chimney in several parts—continuous flashing along the bottom, step flashing up the sides, and saddle flashing at the top. Cap flashing, mortared or caulked into the chimney, laps over the top edges of the other flashings to prevent water from running behind them.

Continuous flashing protects the joint between a vertical wall and a sloped roof.

Drip edges prevent water from seeping under roofing along the edges of rakes and eaves. They’re applied under roofing felt along eaves and over roofing felt along rakes.

Skylights often have their own integral flashing. Otherwise, their curbs are flashed with continuous flashing along the base, step flashing up the sides, and saddle flashing across the top.

Step flashing steps up a roof to protect where the roof meets the side walls of dormers, chimneys, and some skylights. It consists of a series of right-angled metal pieces; each section is worked into a course of shingles so that it overlaps the section beneath it. The flashing’s vertical edge is usually tucked under siding or capped with a second counter flashing that is mortared into the chimney or caulked along a skylight so water can’t sneak in behind it.


Valley flashing protects the valleys where two roof planes meet. This W-shaped channel is placed over the top of building felt before the roof’s finishing material is installed.

Vent pipe flashing fits over flues and pipes. It is cone-shaped with a flange at the base, which is worked into the shingles as the roofing is applied.
(According to Wikipedia)

A roof is part of a building envelope. It is the covering on the uppermost part of a building or shelter which provides protection from animals and weather, notably rain or snow, but also heat, wind and sunlight. The word also denotes the framing or structure which supports that covering.[1]

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. In most countries a roof protects primarily against rain. A verandah may be roofed with material that protects against sunlight but admits the other elements. The roof of a garden conservatory protects plants from cold, wind, and rain, but admits light.

Shack made of date palm branches at Neot Semadar, Israel

A roof may also provide additional living space, for example a roof garden.

Etymology

Old English hrof "roof, ceiling, top, summit; heaven, sky," also figuratively, "highest point of something," from Proto-Germanic *khrofam (cf. Dutch roef "deckhouse, cabin, coffin-lid," Middle High German rof "penthouse," Old Norse hrof "boat shed").
There are no apparent connections outside the Germanic family. "English alone has retained the word in a general sense, for which the other languages use forms corresponding to OE. þæc thatch" [OED].

Design elements

The elements in the design of a roof are:
The material of a roof may range from banana leaves, wheaten straw or seagrass to laminated glass, copper (see: copper roofing), aluminium sheeting and pre-cast concrete. In many parts of the world ceramic tiles have been the predominant roofing material for centuries, if not millennia. Other roofing materials include asphalt, coal tar pitch, EPDM rubber, Hypalon, polyurethane foam, PVC, slate, Teflon fabric, TPO, and wood shakes and shingles.
The construction of a roof is determined by its method of support and how the underneath space is bridged and whether or not the roof is pitched. The pitch is the angle at which the roof rises from its lowest to highest point. Most US domestic architecture, except in very dry regions, has roofs that are sloped, or pitched. Although modern construction elements such as drainpipes may remove the need for pitch, roofs are pitched for reasons of tradition and aesthetics. So the pitch is partly dependent upon stylistic factors, and partially to do with practicalities.
Some types of roofing, for example thatch, require a steep pitch in order to be waterproof and durable. Other types of roofing, for example pantiles, are unstable on a steeply pitched roof but provide excellent weather protection at a relatively low angle. In regions where there is little rain, an almost flat roof with a slight run-off provides adequate protection against an occasional downpour. Drainpipes also remove the need for a sloping roof.
A person that specializes in roof construction is called a roofer.
The durability of a roof is a matter of concern because the roof is often the least accessible part of a building for purposes of repair and renewal, while its damage or destruction can have serious effects.

Form


Terminology of some roof parts
Main article: List of roof shapes
The shape of roofs differs greatly from region to region. The main factors which influence the shape of roofs are the climate and the materials available for roof structure and the outer covering.
The basic shapes of roofs are flat, mono-pitched, gabled, hipped, butterfly, arched and domed. There are many variations on these types. Roofs constructed of flat sections that are sloped are referred to as pitched roofs (generally if the angle exceeds 10 degrees).[2] Pitched roofs, including gabled, hipped and skillion roofs, make up the greatest number of domestic roofs. Some roofs follow organic shapes, either by architectural design or because a flexible material such as thatch has been used in the construction.

Parts


Star-roof lifted into the ESO Supernova Planetarium & Visitor Center.[3]
There are two parts to a roof, its supporting structure and its outer skin, or uppermost weatherproof layer. In a minority of buildings, the outer layer is also a self-supporting structure.
The roof structure is generally supported upon walls, although some building styles, for example, geodesic and A-frame, blur the distinction between wall and roof.

Support

Main article: Domestic roof construction

The roof of a library in Sweden
The supporting structure of a roof usually comprises beams that are long and of strong, fairly rigid material such as timber, and since the mid-19th century, cast iron or steel. In countries that use bamboo extensively, the flexibility of the material causes a distinctive curving line to the roof, characteristic of Oriental architecture.
Timber lends itself to a great variety of roof shapes. The timber structure can fulfil an aesthetic as well as practical function, when left exposed to view.
Stone lintels have been used to support roofs since prehistoric times, but cannot bridge large distances. The stone arch came into extensive use in the ancient Roman period and in variant forms could be used to span spaces up to 140 feet (43 m) across. The stone arch or vault, with or without ribs, dominated the roof structures of major architectural works for about 2,000 years, only giving way to iron beams with the Industrial Revolution and the designing of such buildings as Paxton's Crystal Palace, completed 1851.
With continual improvements in steel girders, these became the major structural support for large roofs, and eventually for ordinary houses as well. Another form of girder is the reinforced concrete beam, in which metal rods are encased in concrete, giving it greater strength under tension.

Outer layer


A bark roof in Korea. See also: Birch-bark roof
Main article: List of commercially available roofing material
This part of the roof shows great variation dependent upon availability of material. In vernacular architecture, roofing material is often vegetation, such as thatches, the most durable being sea grass with a life of perhaps 40 years. In many Asian countries bamboo is used both for the supporting structure and the outer layer where split bamboo stems are laid turned alternately and overlapped. In areas with an abundance of timber, wooden shingles and boards are used, while in some countries the bark of certain trees can be peeled off in thick, heavy sheets and used for roofing.
The 20th century saw the manufacture of composition asphalt shingles which can last from a thin 20-year shingle to the thickest which are limited lifetime shingles, the cost depending on the thickness and durability of the shingle. When a layer of shingles wears out, they are usually stripped, along with the underlay and roofing nails, allowing a new layer to be installed. An alternative method is to install another layer directly over the worn layer. While this method is faster, it does not allow the roof sheathing to be inspected and water damage, often associated with worn shingles, to be repaired. Having multiple layers of old shingles under a new layer causes roofing nails to be located further from the sheathing, weakening their hold. The greatest concern with this method is that the weight of the extra material could exceed the dead load capacity of the roof structure and cause collapse. Because of this, jurisdictions which use the International Building Code prohibit the installation of new roofing on top of an existing roof that has two or more applications of any type of roof covering; the existing roofing material must be removed before installing a new roof.[4]
Slate is an ideal, and durable material, while in the Swiss Alps roofs are made from huge slabs of stone, several inches thick. The slate roof is often considered the best type of roofing. A slate roof may last 75 to 150 years, and even longer. However, slate roofs are often expensive to install – in the USA, for example, a slate roof may have the same cost as the rest of the house. Often, the first part of a slate roof to fail is the fixing nails; they corrode, allowing the slates to slip. In the UK, this condition is known as "nail sickness". Because of this problem, fixing nails made of stainless steel or copper are recommended, and even these must be protected from the weather.[5]
Asbestos, usually in bonded corrugated panels, has been used widely in the 20th century as an inexpensive, non-flammable roofing material with excellent insulating properties. Health and legal issues involved in the mining and handling of asbestos products means that it is no longer used as a new roofing material. However, many asbestos roofs continue to exist, particularly in South America and Asia.
Roofs made of cut turf (modern ones known as green roofs, traditional ones as sod roofs) have good insulating properties and are increasingly encouraged as a way of "greening" the Earth. Adobe roofs are roofs of clay, mixed with binding material such as straw or animal hair, and plastered on lathes to form a flat or gently sloped roof, usually in areas of low rainfall.
In areas where clay is plentiful, roofs of baked tiles have been the major form of roofing. The casting and firing of roof tiles is an industry that is often associated with brickworks. While the shape and colour of tiles was once regionally distinctive, now tiles of many shapes and colours are produced commercially, to suit the taste and pocketbook of the purchaser.
Sheet metal in the form of copper and lead has also been used for many hundreds of years. Both are expensive but durable, the vast copper roof of Chartres Cathedral, oxidised to a pale green colour, having been in place for hundreds of years. Lead, which is sometimes used for church roofs, was most commonly used as flashing in valleys and around chimneys on domestic roofs, particularly those of slate. Copper was used for the same purpose.
In the 19th century, iron, electroplated with zinc to improve its resistance to rust, became a light-weight, easily transported, waterproofing material. Its low cost and easy application made it the most accessible commercial roofing, worldwide. Since then, many types of metal roofing have been developed. Steel shingle or standing-seam roofs last about 50 years or more depending on both the method of installation and the moisture barrier (underlayment) used and are between the cost of shingle roofs and slate roofs. In the 20th century a large number of roofing materials were developed, including roofs based on bitumen (already used in previous centuries), on rubber and on a range of synthetics such as thermoplastic and on fibreglass.

Functions

Insulation

Because the purpose of a roof is to protect people and their possessions from climatic elements, the insulating properties of a roof are a consideration in its structure and the choice of roofing material.
Some roofing materials, particularly those of natural fibrous material, such as thatch, have excellent insulating properties. For those that do not, extra insulation is often installed under the outer layer. In developed countries, the majority of dwellings have a ceiling installed under the structural members of the roof. The purpose of a ceiling is to insulate against heat and cold, noise, dirt and often from the droppings and lice of birds who frequently choose roofs as nesting places.
Concrete tiles can be used as insulation. When installed leaving a space between the tiles and the roof surface, it can reduce heating caused by the sun.
Forms of insulation are felt or plastic sheeting, sometimes with a reflective surface, installed directly below the tiles or other material; synthetic foam batting laid above the ceiling and recycled paper products and other such materials that can be inserted or sprayed into roof cavities. So called Cool roofs are becoming increasingly popular, and in some cases are mandated by local codes. Cool roofs are defined as roofs with both high reflectivity and high thermal emittance.
Poorly insulated and ventilated roofing can suffer from problems such as the formation of ice dams around the overhanging eaves in cold weather, causing water from melted snow on upper parts of the roof to penetrate the roofing material. Ice dams occur when heat escapes through the uppermost part of the roof, and the snow at those points melts, refreezing as it drips along the shingles, and collecting in the form of ice at the lower points. This can result in structural damage from stress, including the destruction of gutter and drainage systems.

Drainage

The primary job of most roofs is to keep out water. The large area of a roof repels a lot of water, which must be directed in some suitable way, so that it does not cause damage or inconvenience.
Flat roof of adobe dwellings generally have a very slight slope. In a Middle Eastern country, where the roof may be used for recreation, it is often walled, and drainage holes must be provided to stop water from pooling and seeping through the porous roofing material.
Similar problems, although on a very much larger scale, confront the builders of modern commercial properties which often have flat roofs. Because of the very large nature of such roofs, it is essential that the outer skin be of a highly impermeable material. Most industrial and commercial structures have conventional roofs of low pitch.
In general, the pitch of the roof is proportional to the amount of precipitation. Houses in areas of low rainfall frequently have roofs of low pitch while those in areas of high rainfall and snow, have steep roofs. The longhouses of Papua New Guinea, for example, being roof-dominated architecture, the high roofs sweeping almost to the ground. The high steeply-pitched roofs of Germany and Holland are typical in regions of snowfall. In parts of North America such as Buffalo, USA or Montreal, Canada, there is a required minimum slope of 6 inches in 12 inches, a pitch of 30 degrees.
There are regional building styles which contradict this trend, the stone roofs of the Alpine chalets being usually of gentler incline. These buildings tend to accumulate a large amount of snow on them, which is seen as a factor in their insulation. The pitch of the roof is in part determined by the roofing material available, a pitch of 3/12 or greater slope generally being covered with asphalt shingles, wood shake, corrugated steel, slate or tile.
The water repelled by the roof during a rainstorm is potentially damaging to the building that the roof protects. If it runs down the walls, it may seep into the mortar or through panels. If it lies around the foundations it may cause seepage to the interior, rising damp or dry rot. For this reason most buildings have a system in place to protect the walls of a building from most of the roof water. Overhanging eaves are commonly employed for this purpose. Most modern roofs and many old ones have systems of valleys, gutters, waterspouts, waterheads and drainpipes to remove the water from the vicinity of the building. In many parts of the world, roofwater is collected and stored for domestic use.
Areas prone to heavy snow benefit from a metal roof because their smooth surfaces shed the weight of snow more easily and resist the force of wind better than a wood shingle or a concrete tile roof.

Solar roofs

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.
Solar systems can be integrated with roofs by:
  • integration in the covering of pitched roofs, e.g. solar shingles.
  • mounting on an existing roof, e.g. solar panel on a tile roof.
  • integration in a flat roof membrane using heat welding, e.g. PVC.
  • mounting on a flat roof with a construction and additional weight to prevent uplift from wind.

Gallery of roof shapes

Gallery of significant roofs

Roof components
History
A roofer or roof mechanic is a construction worker who specializes in roof construction. Roofers concentrate on the application of materials that waterproof and/or weatherproof buildings, designed material—as a substrate for the roofing materials to be installed on, the rafters, beams, and trusses are the frame or skeleton for the roof to be built upon. Roofers must be able to work, have good motor skills and possess general carpentry skills.

In the United States and Canada, they're often referred to as roofing contractors. The most common roofing material in the United States is asphalt shingles. In the past, 3-tab shingles were used; nowadays, "architectural" or "dimensional" shingles are becoming very popular.[1]

Depending on the region, other commonly applied roofing materials installed by roofers include concrete tiles, clay tiles, natural or synthetic slate, single-ply (Primarily EPDM or Rubber, PVC, or TPO), rubber shingles (made from recycled tires), glass, metal panels or shingles, wood shakes or shingles, liquid-applied, hot asphalt/rubber, foam, thatch, solar tiles, and specialty roofs like Duro-Last. "Living roof" systems, or rooftop landscapes, have become increasingly common in recent years in both residential and commercial applications.[2][3]

In the United States, regulation of the roofing trade is left up to individual states. In California, for example, the California Contractors State License Board licenses and monitors roofing contractors.[4]

Unlicensed contracting of projects worth over a set threshold may result in stiff fines or even time in prison.[5]

 The United Kingdom has no legislation in place that requires a roofer to have a license to trade, although some do belong to recognized trade organizations.

Types of Roofers

There are 4 main types of roofers: shinglers, who primarily install shingles, shakes, tiles, and other nail-on products on roofs with 5:12 pitches or above; metal roofers, who focus on metal panels; single-ply or "flat" roofers, who focus on roofs such as single-ply or foam roofs; and "hot" roofers, who work using tar-based products. It is not uncommon, however, for companies to have their roofers to multiple styles of roofing, and certain manufactures will only allow specifically selected installers, thus making these 4 types limiting.

(According to NationalHomeImprovement.com)

Roofing involves many different types of shingle designs and materials to create the desired appearance and protection for your home. A little research will help you understand the different types of roofing options you have available for your home. Below are the most common styles and materials.

3 Tab Shingles

Giving a less dimensional effect to your roofs looks, 3 tab shingles traditionally are also thinner which contributes to the less dimensional look. Normally since these shingles ARE thinner, it effects the length of the warranty.





Dimensional Shingles

Also commonly referred to as architectural or laminated shingle, these are a very popular choice for roofing.  These shingles often have 30+ year warranties and because of popularity have many different styles to choose from.

Premium Shingles

Premium shingles may vary from manufacturer to manufacturer but, these are normally shingles with more design and material improvements. Some premium shingle improvements may include being double lamanent, fiberglass reinforced or adhesion. Premium shingles usually have a longer warranty because of these improvements for longevity and durability.

Impact Resistant Roofing Shingles

Like their name says they are more resistant to impact than traditional shingles. Many of these shingles are tested at high wind speeds to ensure the best resistance to hail and other impacts. To be “impact rated” these shingles are tested using the UL 2218 standard, which includes impacts from a steel ball at various locations. These shingles are recommended for homes in areas that storms or higher impact debris is more frequent.

Shakes

While giving a beautiful rustic look, roof shakes are usually a less popular options because of their traditional cedar or wood construction. Today, shakes are a style easily replicated with more durable and long lasting materials like fiberglass. This significantly lowers the maintenance and still delivers the shake appearance.

Tiles

Typically built from clay, tile roofing is great for helping to insulate your home while creating a beautiful appeal. Tile roofing can be incredibly resilient to harsh weather and with recent improvements to combining alternative materials they have also become a lighter alternative. This helps to lighten the weight of the tiles to reduce the need to reinforce your roof’s construction.

(According to Glossary of Roofing Terms - GAF.com)

Algae

Rooftop fungus that can leave dark stains on roofing.

Angled Fasteners

Roofing nails and staples driven into decks at angles not parallel to the deck.

Apron Flashing

Metal flashing used at chimney fronts.

ARMA

Asphalt Roofing Manufacturers Association. Organization of roofing manufacturers.

Asphalt

A bituminous waterproofing agent used in various types of roofing materials.

Asphalt Concrete Primer

Asphalt based primer used to prepare concrete and metal for asphalt sealant.

Asphalt Plastic Cement

Asphalt based sealant material, meeting ASTM D4586 Type I or II. Used to seal and adhere roofing materials. Also called mastic, blackjack, roof tar, bull.

ASTM

The American Society for Testing and Materials. Organization that sets standards for a wide variety of materials, including roofing.

Back Surfacing

Granular material added to shingle’s back to assist in keeping separate during delivery and storage.

Blistering

Bubbles or pimples in roofing materials. Usually moisture related. In shingles blisters are caused by either moisture under the material or moisture trapped inside the material.

Blow-Offs

When shingles are subjected to high winds, and are forced off a roof deck.

Buckling

When a wrinkle or ripple affects shingles or their underlayments. 

 Closed Cut Valley

A shingle valley installation method where one roof plane’s shingles completely cover the other’s. The top layer is cut to match the valley lines.

Cobra®

GAF’s respected brand name for ventilation products.

Counter Flashing

The metal or siding material that is installed over roof-top base flashing systems.

Country Mansion®

GAF’s limited lifetime warranty shingle.

Crickets

A peaked water diverter installed behind chimneys and other large roof projections. Effectively diverts water around projections.

Cupping

When shingles are improperly installed over an existing roof or are over-exposed, they may form a curl or cup. May also be due to a manufacturing defect.


Deck

The substrate over which roofing is applied. Usually plywood, wood boards, or planks.

Deck Armor™

Deck Armor™ - premium breathable roof deck protection. It provides a critical extra layer of protection between your shingles and your roof deck — to help prevent wind-driven rain (or water from other sources) from infiltrating under your shingles and causing damage to your roof structure or to the inside of your home.

Dormer

A raised roof extending out of a larger roof plane.

Drip Edge

An installed lip that keeps shingles up off the deck at edges, and extends shingles out over eaves and gutters, and prevents

Dubl-Coverage Mineral Guard®

Roll roofing material with 19" selvage edge for double coverage over roof deck. 

Eaves

The roof edge from the fascia to the structure’s outside wall. In general terms, the first three feet across a roof is termed the eave.

End Laps

When installing rolled products in roofing, the area where a roll ends on a roof, and is overlapped by the next section of rolled material.
EWA

Engineered Wood Association. Tests and sets standards for all varieties of plywood used in the U.S.

Exposure

The area on any roofing material that is left exposed to the elements. 

Fasteners

Nails or staples used to secure roofing to the deck.

FHA

The Federal Housing Authority sets construction standards throughout the U.S.

Fiberglass Mat

Fibers condensed into strong, resilient mats for use in roofing materials.

Flange

Metal pan extending up or down a roof slope around flashing pieces. Usually at chimneys and plumbing vents

Flashing

Materials used to waterproof a roof around any projections

Flashing Cement

Sealant designed for use around flashing areas, typically thicker than plastic cement.

Gable Roof

Traditional roof style; two peaked roof planes meeting at a ridge line of equal size.

GAFCant

GAF cant strips for deflecting water away from flashing areas. Typically used on low slope roofs.

Golden Pledge®

GAF’s strongest limited warranty for shingles. America’s strongest steep slope warranty.

Grand Sequoia®

GAF shingle with wood shake appearance.

Grand Slate™

GAF shingle with slate appearance.

Granules

Crushed rock that is coated with a ceramic coating and fired, used as top surface on shingles.

Hand-Sealing

The method to assure sealing of shingles on very steep slopes, in high wind areas, and when installing in cold weather.

High Nailing

When shingles are nailed or fastened above the manufacturer’s specified nail location.

Hip Legs

The down-slope ridges on hip roofs.

Hip Roof

A roof with four roof planes coming together at a peak and four separate hip legs. 

Ice Dam

When a snow load melts on a roof and re-freezes at the eave areas. Ice dams force water to "back-up" under shingles and cause leakage.


"L" Flashing

Continuous metal flashing consisting of several feet of metal. Used at horizontal walls, bent to resemble an "L".

Laminated Shingles

Shingles made from two separate pieces that are laminated together such as GAF Timberline® Series, Country Mansion® and Grand Sequoia® Shingles. Also called dimensional shingles and architectural shingles.

Laps

The area where roll roofing or rolled underlayments overlap one another during application (see also side laps and end laps).
Liberty™

Self-adhering low-slope roofing. Liberty™ systems are applied without torches, open flames, hot asphalt, or messy solvent-based adhesives.

Low Slopes

Roof pitches less than 4:12 are considered low sloped roofs. Special installation practices must be used on roofs sloped 2:12-4:12. Shingles can not be installed at slopes less than 2/12.

Mansard
A roof design with a nearly vertical roof plane that ties into a roof plane of less slope at its peak.

Mats
The general term for the base material of shingles and certain rolled products.

Modified bitumen
Rolled roofing membrane with polymer modified asphalt and either polyester or fiberglass reinforcement.

Mortar
Mixture of sand, mortar, limestone and water used in bonding a chimney’s bricks together.

Nail Guide Line

Painted line on laminated shingles, to aid in the proper placement of fasteners.

Nail-Pop

When a nail is not fully driven, it sits up off the roof deck.

Nesting

Installing a second layer of shingles aligning courses with the original roof to avoid shingle cupping.

NRCA

The National Roofing Contractors Association. Respected national organization of roofing contractors.

Open Valley

Valley installation using metal down the valley center.

Organic Mat

Material made from recycled wood pulp and paper.

Organic Shingles

Shingles made from organic (paper) mats.

OSB

Oriented Strand Board. A decking made from wood chips and lamination glues.

Overdriven

The term used for fasteners driven through roofing material with too much force, breaking the material.

Overexposed

Installing shingle courses higher than their intended exposure.

Quarter Sized

Term for the size of hand sealant dabs, size of a U.S. 25¢ piece. 

 Racking

Method of installing shingles in a straight up the roof manner.

Rake Edge

The vertical edge of gable style roof planes.

Release Film

The plastic sheet installed on the back of WeatherWatch® and StormGuard® underlayments. Used for packaging and handling. Remove before installation.

Rigid Vent

Hard plastic ridge vent material.

Roof Louvers

Rooftop rectangular shaped roof vents. Also called box vents, mushroom vents, airhawks, soldier vents.

Roof Plane

A roofing area defined by having four separate edges. One side of a gable, hip or mansard roof.

Sawteeth

The exposed section of double thickness on Timberline® Series shingles - also called dragon teeth. Shaped to imitate wood shake look on the roof.

Self-Sealant

Sealant installed on shingles. After installation, heat and sun will activate sealant to seal the shingles to each other.

Selvage

The non exposed area on rolled roofing. Area without granules. Designed for nail placement and sealant.

Shed Roof

Roof design of a single roof plane. Area does not tie into any other roofs.

Shingle-Mate®

GAF’s shingle underlayment. Breather type with fiberglass backing to reduce wrinkles and buckles.

Side Laps

The area on rolled material where one roll overlaps the rolled material beneath it. Also called selvage edge on rolled roofing.

Side Walls

Where a vertical roof plane meets a vertical wall. The sides of dormers etc.

Soffit Ventilation

Intake ventilation installed under the eaves, or at the roof edge.

GAF Shingle & Accessory Ltd. Warranty

GAF’s standard shingle limited warranty.

Starter Strip

The first course of roofing installed. Usually trimmed from main roof material.

Steep-Slope Roofing

Generally all slopes higher than 4/12 are considered steep slopes.

Stepflashing

Metal flashing pieces installed at sidewalls and chimneys for weatherproofing.

StormGuard®

GAF waterproof underlayment. Film-surfaced rolled underlayment, 1.5 squares coverage per roll. 

Tab

The bottom portion of traditional shingle separated by the shingle cut-outs.

Tear-Off

Removal of existing roofing materials down to the roof deck.

Telegraphing

When shingles reflect the uneven surface beneath them. Ex: Shingles installed over buckled shingles may show some buckles.

Timberline® Series

GAF’s trademark name for laminated wood-shake-style shingles.

TimberTex®

GAF enhanced Hip and Ridge Shingles.

Transitions

When a roof plane ties into another roof plane that has a different pitch or slope. 

Underdriven

Term used to describe a fastener not fully driven flush to the shingles surface.

Underlayments

Asphalt-based rolled materials designed to be installed under main roofing material to serve as added protection.

Valleys

Area where two adjoining sloped roof planes intersect on a roof creating a "V" shaped depression.

Vapor

Term used to describe moisture laden air.

Warm Wall

The finished wall inside of a structure, used in roofing to determine how far up the deck to install waterproof underlayments at eaves.

Warranty

The written promise to the owner of roofing materials for material related problems.

Waterproof Underlayments

Modified bitumen based roofing underlayments. Designed to seal to wood decks and waterproof critical leak areas.

Weather Stopper® Integrated Low-Slope Roofing System™

GAF’s complete roofing system and components.

Weather Stopper System Plus Ltd. Warranty
Plus Limited Warranty

GAF’s next grade of enhanced warranty. Extended coverage for owners.

WeatherWatch®

GAF’s granule-surfaced waterproof underlayment.

Woven Valleys

The method of installing valleys by laying one shingle over the other up the valley center.

(According to Wikipedia)

Flashing refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier (WRB) system.

Entympology & Related Terms

The origin of flash and flashing are uncertain,[1] but may come from the Middle English verb flasshen, 'to sprinkle, splash', related to flask.[2]

Counter-flashing (or cover flashing, cap flashing) is a term used when there are two parallel pieces of flashing employed together[3] such as on a chimney, where the counter-flashing is built into the chimney and overlaps a replaceable piece of base flashing. Strips of lead used for flashing an edge were sometimes called an apron,[4] and the term is still used for the piece of flashing below a chimney. The up-hill side of a chimney may have a small gable-like assembly called a cricket with cricket flashing or on narrow chimneys with no cricket a back flashing or back pan flashing. Flashing may be let into a groove in a wall or chimney called a reglet.

Purpose of Roof Flashing

Before the availability of sheet products for flashing carpenters used creative methods to minimize water penetration such as angling roof shingles away from the joint, placing chimneys at the ridge, and building steps into the sides of chimneys to throw off water. The introduction of manufactured flashing decreased water penetration at obstacles such as chimneys, vent pipes, walls which abut roofs, window and door openings, etc. thus making buildings more durable and reducing indoor mold problems. In builders books, by 1832 Loudons An Encyclopædia of Cottage, Farm, and Villa Architecture and Furniture... gives instruction on installing lead flashing and 1875 Notes on Building Construction gives detailed instruction and is well illustrated with methods still used today.[5]
Flashing may be exposed or concealed. Exposed flashing is usually of a sheet metal and concealed flashing may be metal or a flexible, adhesive backed, material particularly around wall penetrations such as window and door openings.

Roof Flashing Materials

In earlier days, birch bark was occasionally used as a flashing material.[6] Most flashing materials today are metal, plastic, rubber, or impregnated paper.[7]

Metal flashing materials include lead, aluminium, copper,[8] stainless steel, zinc alloy, other architectural metals or a metal with a coating such as galvanized steel, lead-coated copper, anodized aluminum, terne-coated copper, galvalume (aluminum-zinc alloy coated sheet steel), and metals similar to stone-coated metal roofing. Metal flashing should be provided with expansion joints on long runs to prevent deformation of the metal sheets due to expansion and contraction, and should not stain or be stained by adjacent materials or react chemically with them. An important type of potential chemical reaction between metal flashing materials is galvanic corrosion. Copper and lead cannot be used in contact with or even above aluminum, zinc, or coated steel without an increased risk of premature corrosion. Also, Aluminum and zinc flashing cannot be used in contact with pressure treated wood due to rapid corrosion. Aluminum is also damaged by wet mortar and wet plaster. Salt spray in coastal areas may accelerate corrosion. so stainless steel, copper, or coated aluminum are recommended flashing materials near salt water.

Types of flexible flashing products are rubberized asphalt, butyl rubber, polyvinylidene fluoride (sometimes known as kylar or hylar), and acrylic.[9] The different types have different application temperature ranges, material adhesion compatibility, chemical compatibility, levels of volatile organic compounds, resistance to ultraviolet light exposure. No flexible flashing material is designed to remain exposed over the long term as are metal flashing materials.[citation needed] Adhesive backed materials are convenient during installation, but such adhesives are not intended for long-term water-resistance.[citation needed]

Copper is an excellent material for flashing because of its malleability, strength, solderability, workability, high resistance to the caustic effects of mortars and hostile environments, and long service life (see: copper flashing). This enables a roof to be built without weak points. Since flashing is expensive to replace if it fails, copper’s long life is a major cost advantage.[10][11] Cold rolled (to 1/8-hard temper) copper is recommended for most flashing applications. This material offers more resistance than soft copper to the stresses of expansion and contraction. Soft copper can be specified where extreme forming is required, such as in complicated roof shapes. Thermal movement in flashings is prevented or is permitted only at predetermined locations.[12]

"Soft zinc" is a newer, proprietary flashing material. It is a relatively malleable material, making it useful for complex roofing connections. It provides normal soft soldering capabilities and delivers easy folding. Soft zinc is said to be an "environmentally friendly" replacement for lead flashing; like lead, it is recyclable, while avoiding lead-contaminated runoff.[13]

Types

Flashing types are named according to location or shape:
  • Roof flashing is placed around discontinuities or objects which protrude from the roof of a building to deflect water away from seams or joints and in valleys where the runoff is concentrated.
  • Wall flashing may be embedded in a wall to direct water that has penetrated the wall back outside, or it may be applied in a manner intended to prevent the entry of water into the wall. Wall flashing is typically found at interruptions in the wall, such as windows and points of structural support.
  • Sill flashing or sill pan is a concealed flashing placed under windows or door thresholds to prevent water from entering a wall at those points.
  • Roof penetration flashing are used to waterproof pipes, supports, cables, and all roof protrusions. Stainless steel penetration flashings have proven to be the longest lasting and most reliable roof flashing type.
  • Channel flashing is shaped like a U or channel to catch water such as where the edge of a tile roof meets a wall.
  • Through wall flashing – Spans the thickness of the wall and directs water to weep holes.
  • Cap flashing (drip cap) often used above windows and doors
  • Drip edge – A metal used at the edges of a roof
  • Step flashing (soaker, base flashing) – Pieces of flashing material which overlap each other in "steps".
  • Counter flashing (cap flashing) – Covers a base flashing.
  • Pipe flashing – (pipe boot, vent boot, pipe flange) A product used where pipes penetrate roofs.
  • Chimney flashing – A general term for flashing a chimney.
  • Kickout flashing – At the very bottom of a roof/wall intersection, the lowermost step flashing specially formed to deflect water away from the wall.
  • Valley flashing – In the valley of two intersecting roof planes.
A structure incorporating flashing has to be carefully engineered and constructed so that water is directed away from the structure and not inside. Flashing improperly installed can direct water into a building.

Environmental Impact

In the US and UK, at least, lead flashing and fittings are still readily available, despite the environmental concerns associated with bulk use of this heavy metal. The Lead Sheet Association touts its recyclability and extreme durability, 500 years, compared to modern materials that can fail within 20 years.[14]

See Also


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