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Timber and timber products
Published in Arthur Lyons, Materials for Architects and Builders, 2019
Long straw roofs show the lengths of the individual straws down the roof surface and are also characterised by the use of split hazel rodding around the eaves and gables to secure the thatch. To prevent attack by birds, they are frequently covered in netting. Combed wheat reed and water reed both have a closely packed finish, with the straw ends forming the roof surface. A pitch of about 50° is usual for thatch, with a minimum of 45°, the steeper pitches being more durable. The ridge, which may be a decorative feature, is produced by either wrapping wheat straw over the apex or butting up reeds from both sides of the roof. Traditionally, hazel twigs are used for fixings, although these can be replaced with stainless steel wires. The durability of thatch is significantly affected by the climate. All materials tend to have shorter service lives in warmer locations with high humidity, which encourage the development of fungi. Chemical treatment, consisting of an organic heavy metal compound, may be used, preferably on new thatch, to delay the biological decomposition. Thatch is usually laid to a thickness of between 220 and 400 mm.
Roofings
Published in Michael McEvoy, External Components, 2014
Thatching has the advantage of being adaptable to different plan forms, lightweight, and providing good thermal insulation and sound control. In addition, gutters and downpipes are not required, and the materials make use of a renewable resource (unless synthetic). Its main disadvantage is in relation to fire control; thatch has no classification within the Building Regulations 1991 which consequently require that a thatched roof must be more than 22 m from a boundary. For this reason, insurance companies are reluctant to provide a fire policy for a thatch roof covering. The Thatching Advisory Service Ltd recommend the use of a fire-retardant treatment consisting of a chemical water-based solution which is injected by means of a multi-headed spray lance into the thatch. When the chemical dries, the individual straws or reeds of the thatch remain coated with a deposit of the fire-resistant material. However, weathering causes this deposit to wear off at the top of the ridge and the outer surface of the roof; a better method is to dip the bundles in the retardant prior to thatching. It is also possible to install external sparge pipes at the ridge position which will cause the roof to be sprayed with water in the event of a fire. Other precautions can also be taken, such as providing an underlining of a material having a class 0 spread of flame rating, running electric wiring in conduit to BS 31/4568 or MICC to BS 6207 within roof spaces, locating television aerials and cables on masonry, and ensuring properly constructed and maintained chimneys.
Environmental assessment of buildings in Sudan
Published in Klára Szita Tóthné, Károly Jármai, Katalin Voith, Solutions for Sustainable Development, 2019
The building materials in Sudan are classified into three types: (a) modern materials: i.e. concrete, red bricks with cement mortar, cement bricks and corrugated iron sheets; (b) traditional permanent materials: red bricks combined with mud bricks for wall construction, mud construction for walls and roofing made from sticks, thatch and mud; and (c) traditional materials: i.e. thatch used for roofing and for walls. In first class areas, residential buildings are made of red bricks with clay or cement mortar, reinforced concrete ceilings, and roofs or corrugated iron sheets for roofing (Elkhalifa 2011, NCR 2003).
Demand for improved sanitation in an urban informal settlement in India: role of the local built environment
Published in International Journal of Environmental Health Research, 2019
Finally, four more commonly used explanatory variables were also included. Household size was a discrete measure that was regrouped into three categories: 1–2 people, 3–5 people, and 6 or more, based on its distribution. Presence of any female children was entered as a dichotomous variable – given that ‘toilet insecurity’ may be a gendered phenomenon (O’Reilly 2016), having female children at home was thought to be a potentially useful explanatory variable. The structure of the house was entered based on Indian categories commonly used in the literature as well as by the Indian government. Pucca housing indicates the use of fortified materials for the floors, walls, and roof, such as concrete, whereas Kutccha involves less permanent materials like mud, thatch, or tarpaulin. Semi-pucca entails both types of materials. Based on their distributions, Pucca and Semi-pucca were collapsed into a single group. The house area in square feet had been entered as an ordinal category; based on its distribution it was organized as a dichotomous variable, for less than 200 square feet and more than 200.