Thatching

Reet (also: Reeth, Reth, Reith, reed, reed, cane, and the like ) refers to the on shore or on marshy terrain growing reed, which is widely used in the dry state for roofing and served in earlier times many similar purposes, such as for embroidery of new dikes with the dike nobility.

The name thatched roof has nationwide enforced for these roofing form, sometimes it is also called pipe roof. A thatched house is also known as Thatched or Reethus.

History

Thatch or reed was one of the first roofing materials of sedentary people; this is mainly due to its properties as a water plant and its local availability. The first thatched roofs were simple Eindach houses.

In the Middle Ages the thatched roof was replaced in the cities by hard roofs due to the fire hazard in densely built-up areas. In the country, however, the Reet maintained a certain importance to the present time. The first documented thatched roofs ( stilt houses on Lake Constance ), there were already around 4000 BC It was easy aufgebundenes thatch, which was pressed with hazelnut sticks as a shaft rod and soaked willow sticks on the roof.

Dissemination

In many areas of Europe, Asia and Africa are known thatched roofs. In many cases, however, these are particularly associated with the North Sea and Baltic Sea area, where you will find fully thatched building or the East Frisian Reeteindeckung Gulfhöfe for example in North Frisia. Also typical for northern Friesland Uthlandfriesische home is traditionally provided with a thatched roof. In some places, such as Kampen on Sylt, there are statutes which require the exclusive use of thatch, which is the so-called " soft roofing". In the neighboring villages Westerland Westerland and there are districts or areas where also only thatched roofs can be built. On the eiderstedt peninsula are the distinctive large farmhouses, Haubarge, traditionally covered with thatch. The thatched or Rohrdachdeckerei is a separate area of ​​business, so there are special thatcher in northern Germany, which only create and repair these roofs.

In the Midlands of England and in Cornwall Thatched roofs are also widespread. Tradition are particularly ornate, built-up ridge caps. A variant is the traditional on the Danish island of Læsø roof made ​​of seaweed.

Construction

A thatched roof can be run as a cold roof ( with ventilation ) traditionally, formerly the thatch or straw roof was constructed without ventilation as a warm roof. The excellent insulating properties of the building material came reeds into play: Due to the low density of reed thatch makes for good summer heat protection and excellent heat insulation in the winter. In the course of modern construction techniques, the thatched roofs, however, have adapted to their base and are now built with rear ventilation (according to DIN 4108 ) as a cold roof. The ventilation dissipates resulting moisture and thus ensures a longer life for the thatched roof.

The correct execution must comply with some requirements and parameters. Thatched roofs should have a roof pitch of 45 °. The high roof pitch is required in order to slide the individual drops of water from stem to stem. In a functioning thatched roof so only the top layer of roofing is moistened. Thatched roofs have a constructive Building a large roof overhang ( Traufüberstand ) of at least 50 cm, as no rain gutter discharges the water, it drips at a sufficient distance from the brickwork and seeps in a gravel bed or is discharged through a chute. The chimney outlet must be at least 0.8 m above the ridge, according Combustion ( FeuVO ).

The ridge of the thatched roof is made varies from region to region. In regions where the heather grows, it will be covered with heather. In the Netherlands, Flanders and France Tonkappenfirste are ( fired in natural red or dove gray damped) usual. In North Frisia is the grass sod ridge is to find and in the Scandinavian countries and the Kappeln / Flensburg hanging Holzer region (oak Rider ), which depend on a seaweed layer.

Processing

A thatched roof can be prepared in three different ways: as screwed, stitched or bound roof. The reed is supplied in bundles laced, distributed to the roof battens and then shifted so that the lower Reethalmenden form an inclined uniform, continuous surface. The root ends of the reed facing the floor. The first layer, the so-called Traufschicht is held under tension by the bonding to the roof. The tension gets the coverage in that the bearing edge at the eaves ( Kniep ) five to seven centimeters higher than the roof batten level. In the bound and screwed roofs a retaining wire (shaft ) is placed on the approximately one meter wide and 10-20 cm layers and pressed by a bolted or bonded wire on the situation. With the knock board, the layers are highly tapped and brought into shape. This will be continued layer by layer until it reaches the roof ridge by the overlapping of the individual layers is based on the binding in the middle of the top layer. The sewn thatch comes from without retaining wire and to process complicated.

Life

A thatched roof will typically last 30 to 50 years, but there are also documented roofs that were over 100 years old. The lifespan of a thatched roof is of different criteria depending on:

• Form and execution details (eg roof pitch, number of dormers, Halmneigung )
• The thatched roof ventilation (ventilation habits of the inhabitants )
• Construction of the roof ( traditionally ventilated or not ventilated )
• Quality of Dachreets used ( installation moisture )
• Position of the thatched roof ( thatched roof location of the site, in the region)
• Care and maintenance of thatched roof ( regular maintenance and repair, for example, by so-called combing )

Settlement cycle

The reed Phragmites australis is home to numerous other species. With progressive life of the roof colonization changes. The following steps show the typical vegetation. This growth sequence can be disrupted by weather conditions and maintenance work. The species composition differs from region to region and depends on the direction and shading also in a single roof.

• During the first year: the beginning of the colonization of air algae, green algae, diatoms and lichens.
• Year 6: Further colonization with leaf lichens and lichens.
• From 10 years: Now the Gabelzahnperlmoos Dicranoweisia cirrata follows.
• From the 15th year: On the existing moss beds possibilities epigeic moss species settle on, depending on the local moisture
• From the 20th year begin flowering plants (herb and shrub species ) replace the Moose.

Metals

Among experts there is currently a lively discussion about whether copper products, can be used, for example, binding wires of copper or quaternary ammonium compounds for the care of a thatched roof in order to prolong the shelf life and thus the lifetime of a thatched roof.

Copper in the first region is said that the released ions through the rain reduce the moss and lichen growth on the roof area. On the other hand the reed has an influence on metals. For example, if a gutter is constructed at the entrance, it should consist of an acid-resistant material. Zinc is eaten away in a few years. Aluminum and copper have proven themselves more.

Reetproblematik today

Currently, Reet is also imported to Germany, because the demand is higher than the domestic supply. Today, about half of the Reets from Romania is imported, also from Ukraine and Hungary; about ten percent come from Turkey and China ( combined with other harvesting periods). In this context, concerns have been raised by the import of pests could be introduced that have no natural enemies and would reduce the durability or life of the roof covering.

Much attention gained reports of mysterious fungal species that have been stylized in the media to " Killer Mushrooms ". Such new mushrooms, supposedly introduced by imports from South-Eastern Europe, and their effects, however, were detected by any tests, and according to some references the source of some of these theories, the manufacturer of an alleged agent against the fungi was.

Research at the University of Greifswald and other participating universities in Northern Germany could find no evidence of such a fungus or pest. The research revealed that only lignin (wood) may be responsible degrading fungi ( white rot fungi ) for the premature aging of thatched roofs, if them a conducive environment is provided by continuous moisture. This environment is created but only by building physical errors.

The Dutch guild Vakfederatie Rietdekkers presumed similar to the cause of the decay of many thatched roofs lie more in non- compliance with the basic principles of the roof structure ( for example, the roof pitch ) and in the use of low-quality reeds, which leads to increased moisture; However, the inferior Reet does not necessarily come from South Eastern Europe to Germany alone - even Reetreste that are used in the Netherlands for lack of quality no use, imported to Germany.

Fire hazard

Thatched roofs are, especially in high summer, fire risk if they are dried out by the sun. But the New Year's Eve fireworks display is a threat, so that the burning of fireworks was strictly forbidden on the North Frisian Islands. A fire spreads, normally within half an hour from a large area; Laced Reetbündel loosen and slip burning from the roof surface so that it can be difficult to escape from the building. The fire departments advise mostly to leave the building during a fire immediately. This problem has been known for centuries, so that is expected, locally even earlier, distributed so-called fire doors from the late 18th century (see also photo " Uthlandfriesisches house" ) These are located on the sides of the house and have their own gable, so that protect them when leaving the building before the burning Reetbündeln. Because of the opposite of a hard roof considerably higher fire risk premiums for fire insurance in traditional thatched houses are higher. A public real fire test at the Fachhochschule Lübeck has shown that the current binding technology with bolted V2A wires and without ventilation on a solid wood roof (Regional House Bay of Lübeck (R ) ) resulted in a burn on the roof surface. The reed does not slip down. The LBO -SH § 34 was subsequently amended accordingly in 2009.

Gallery

Uthlandfriesisches Öömrang Hus on Amrum

Red Haubarg in eiderstedt

Thatched house in the Heath Kampen on Sylt

Thatched reception building of the Berlin U -Bahn station Dahlem-Dorf

Thatched cottage in the Danish Wold

Thatched roof of a cottage in the Holy wine cellar district