In equatorial countries thatch is the prevalent local material for roofs, and often walls. There are diverse building techniques from the ancient Hawaiian hale shelter made from the local ti leaves, lauhala or pili grass of fan palms to the Na Bure Fijian home with layered reed walls and sugar cane leaf roofs and the Kikuyu tribal homes in Kenya. The colonisation of indigenous lands by Europeans greatly diminished the use of thatching. Thatch has probably been used to cover roofs in Europe since at least the Neolithic period, when people first began to grow cereals. Wild vegetation, especially water reed (Phragmites australis), was probably used before this but no records or archaeological evidence for this have survived ”.
Early settlers to the New World used thatch as far back as 1565. Native Americans had already been using thatch for generations. When settlers arrived in Jamestown, Virginia in 1607, they found Powhatan Indians living in houses with thatched roofs. The colonists used the same thatch on their own buildings.
In most of Europe and the UK, thatch remained the only roofing material available to the bulk of the population in the countryside, and in many towns and villages, until the late 1800s. The commercial production of Welsh slate had begun in 1820 and the mobility which the canals and then the railways made possible meant that other materials became readily available. The number of thatched properties actually increased in the UK during the mid-1800s as agriculture expanded, but then declined again at the end of the 19th century because of agricultural recession and rural depopulation. Gradually, thatch became a mark of poverty and the number of thatched properties gradually declined, as did the number of professional thatchers.
Thatch has become much more popular in the UK over the past 30 years, and is now a symbol of wealth rather than poverty. There are now approximately 1,000 full time thatchers at work in the UK, and thatching is becoming popular again because of the renewed interest in preserving historic buildings and using more sustainable building materials.
Technology in the farming industry has had a significant impact on the popularity of thatching. The availability of good quality thatching straw declined in England after the introduction of the combine harvester in the late 1930s and 1940s, and the release of short-stemmed wheat varieties. The increasing use of nitrogen fertiliser in the 1960s-70s also weakened straw and reduced its longevity. Since the 1980s, however, there has been a big increase in straw quality as specialist growers have returned to growing older, tall-stemmed, 'heritage' varieties of wheat such as Maris Wigeon, in low input/organic conditions
All of the evidence indicates that water reed was rarely used for thatching outside of East Anglia. It has traditionally been a 'one coat' material applied in a similar way to how it is used in continental Europe - weathered reed is usually stripped and replaced by a new layer. It takes 4-5 acres of well-managed reed bed to produce enough reed to thatch an average house, and large reed beds have been uncommon in most of England since the Anglo-Saxon period. Over 80% of the water reed used in the UK is now imported from Turkey, Eastern Europe and China. Although water reed might last for 50 years or more on a steep roof in a dry climate, modern imported water reed on an average roof in England will not last any longer than good quality wheat straw. The lifespan of a thatched roof is also dependent on the skill of the thatcher, but other factors need to be taken into account, such as climate, quality of the materials used, and the pitch of the roof.
Thatch is fastened together in bundles with a diameter of about two feet. These are then laid on the roof with the butt end facing out and secured to the roof beams, after which they are pegged in place with wooden or steel rods. The thatcher adds the layers on top of each other, finishing with a layer to secure the ridgeline of the roof. This method means thatch roofs are easy to repair, can endure heavy winds and rain and only need a stable supporting structure.
In areas where palms are abundant, palm leaves are used to thatch walls and roofs. Many species of palm trees are called "thatch palm", or have "thatch" as part of their common names. In the southeastern United States, Indian and pioneer houses were often constructed of palmetto-leaf thatch. The chickees of the Seminole and Miccosukee Indians are still thatched with palmetto leaves.
The thickness of the thatch decreases over the years as the surface is gradually eroded. A thatched roof can be thought to be nearing replacement when the horizontal fixings of each course are close to the surface. “A roof is as good as the amount of correctly laid thatch covering the fixings.”
A spray-on fire retardant or pressure impregnated fire retardant is available that can reduce the spread of flame, and lower the radiated heat output of the fire.
On new buildings a solid fire retardant barrier can be applied over the rafters making the thatch sacrificial in case of fire. If fireboards are used, it is essential that a ventilation gap be left between the boarding and the thatch so that the roof can 'breathe', as condensation can be a significant problem in thin, single layer thatch. Condensation is much less of a problem on thick straw roofs, and because they do not need to be ventilated provide much better insulation. In Ireland and the Isle of Man, turf is laid upon the rafters to form a fire barrier and this is called "scraw".
Thatch has some natural properties that are advantageous to its performance. It is naturally weather-resistant,and when properly maintained does not absorb a lot of water. There should not be a significant increase to roof weight due to water retention. A roof pitch of at least 50 degrees allows precipitation to travel quickly down slope so that it runs off the roof before it can penetrate the structure.
Thatch is also a natural insulator, and air pockets within straw thatch insulate a building in both warm and cold weather. A thatched roof will ensure that a building will be cool in summer and warm in winter.
Thatch also has very good resistance to wind damage when applied correctly.
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.
Thatch has fallen out of favour in much of the industrialised world not because of fire, but because thatching has become very expensive and alternative 'hard' materials are cheaper — but this situation is slowly changing. There are almost 100,000 thatched roofs in the UK, and many more are being built every year.
New thatched roofs were forbidden in London by the Normans in the 12th century, and existing roofs had to have their surfaces plastered to reduce the risk of fire. The Great Fire of London in 1666 had nothing to do with thatch. The modern Globe Theatre is one of the few thatched buildings in London (others can be found in the suburb of Kingsbury), but the Globe's modern, water reed thatch is purely for decorative purpose and actually lies over a fully waterproofed roof built with modern materials. The Globe Theatre, opened in 1997, was modeled on the Rose which was destroyed by a fire on a dry June night in 1613 when a burning wad of cloth ejected from a special effects canon during a performance set light to the surface of the thatch.
Category:Building materials Category:Natural materials Category:Energy conservation Category:Sustainable technologies Category:Cereals
br:Plouz ca:Coberta de palla cs:Došek cy:To gwellt da:Stråtag de:Reet es:Tejados de paja fr:Chaume ga:Ceann tuí ko:초가 hi:छप्पर it:Tetto di paglia nl:Rieten dak ja:茅葺 nrm:Gllu pl:Strzecha sv:StråtakThis text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
The World News (WN) Network, has created this privacy statement in order to demonstrate our firm commitment to user privacy. The following discloses our information gathering and dissemination practices for wn.com, as well as e-mail newsletters.
We do not collect personally identifiable information about you, except when you provide it to us. For example, if you submit an inquiry to us or sign up for our newsletter, you may be asked to provide certain information such as your contact details (name, e-mail address, mailing address, etc.).
When you submit your personally identifiable information through wn.com, you are giving your consent to the collection, use and disclosure of your personal information as set forth in this Privacy Policy. If you would prefer that we not collect any personally identifiable information from you, please do not provide us with any such information. We will not sell or rent your personally identifiable information to third parties without your consent, except as otherwise disclosed in this Privacy Policy.
Except as otherwise disclosed in this Privacy Policy, we will use the information you provide us only for the purpose of responding to your inquiry or in connection with the service for which you provided such information. We may forward your contact information and inquiry to our affiliates and other divisions of our company that we feel can best address your inquiry or provide you with the requested service. We may also use the information you provide in aggregate form for internal business purposes, such as generating statistics and developing marketing plans. We may share or transfer such non-personally identifiable information with or to our affiliates, licensees, agents and partners.
We may retain other companies and individuals to perform functions on our behalf. Such third parties may be provided with access to personally identifiable information needed to perform their functions, but may not use such information for any other purpose.
In addition, we may disclose any information, including personally identifiable information, we deem necessary, in our sole discretion, to comply with any applicable law, regulation, legal proceeding or governmental request.
We do not want you to receive unwanted e-mail from us. We try to make it easy to opt-out of any service you have asked to receive. If you sign-up to our e-mail newsletters we do not sell, exchange or give your e-mail address to a third party.
E-mail addresses are collected via the wn.com web site. Users have to physically opt-in to receive the wn.com newsletter and a verification e-mail is sent. wn.com is clearly and conspicuously named at the point of
collection.If you no longer wish to receive our newsletter and promotional communications, you may opt-out of receiving them by following the instructions included in each newsletter or communication or by e-mailing us at michaelw(at)wn.com
The security of your personal information is important to us. We follow generally accepted industry standards to protect the personal information submitted to us, both during registration and once we receive it. No method of transmission over the Internet, or method of electronic storage, is 100 percent secure, however. Therefore, though we strive to use commercially acceptable means to protect your personal information, we cannot guarantee its absolute security.
If we decide to change our e-mail practices, we will post those changes to this privacy statement, the homepage, and other places we think appropriate so that you are aware of what information we collect, how we use it, and under what circumstances, if any, we disclose it.
If we make material changes to our e-mail practices, we will notify you here, by e-mail, and by means of a notice on our home page.
The advertising banners and other forms of advertising appearing on this Web site are sometimes delivered to you, on our behalf, by a third party. In the course of serving advertisements to this site, the third party may place or recognize a unique cookie on your browser. For more information on cookies, you can visit www.cookiecentral.com.
As we continue to develop our business, we might sell certain aspects of our entities or assets. In such transactions, user information, including personally identifiable information, generally is one of the transferred business assets, and by submitting your personal information on Wn.com you agree that your data may be transferred to such parties in these circumstances.