- •Б1.Б.3. Иностранный язык (английский) Сборник текстов для бакалавров направление 270800 Строительство
- •Методические указания студентам.
- •2. From the history of human dwellings.
- •1. Where did primitive people look for protection?
- •2. What are the earliest types of human dwellings?
- •3. Why were the houses in town higher than in the country?
- •4. What were the houses in ancient Egypt built of?
- •5. How did the light come into early English houses?
- •3. Building materials in the hot climate zones
- •4. Loads
- •5. Walls
- •6. Heating
- •7. Concrete
- •8. Lime
- •9. Portland cement and sand
- •10. Mixing
- •11. Building stones
- •12. Sandstones and limestones
- •13. Walls and partitions Part I
- •Part II
- •14. Walls of bricks
- •15. Disadvantages of the brick walls
- •16. Concrete walls
- •17. Roofs
- •18. Waterproofness
- •19. Fire resistance
- •20. Concrete structures Part I
- •Part II
- •21. Different methods of heating and ventilation
- •Библиографический список
18. Waterproofness
The attainment of waterproofness of a roof is frequently dependent upon the common sense and good judgment used in working out the details of construction and drainage. Obviously, the roofing or covering itself must be watertight, or able to shed the water. The following five general types of roofing are used:
a. Built-up Bituminous Membranes. — These are usually made of layers of roofing felt or fabric coated with asphalt or tar. A series of layers or plies is built up by lapping successive layers, thus obtaining a large, continuous, waterproof sheet of excellent durability. Frequently, this type of roofing is covered with small gravel while the bituminous material is soft. This is done to provide a surface that will resist wear and will not become too soft and sticky under a hot sun; the gravel does not add to the waterproofness. When such roofings are likely to be walked upon frequently, it is advisable to cover them with tiles laid in asphalt, or with some other suitable material. Such built-up roofing is especially advantageous for flat roofs.
b. Prefabricated "Pilot" or Other Bituminous Roofing Papers. * These are generally low-priced but relatively short-lived. As it is difficult to keep the joints tight, they are not used on flat roofs. These roofings are easily and cheaply applied, but the material is readily damaged by workmen walking on the roof, by wind, branches of trees, and ice.
c. Metalic Sheets. — These may be noncorrodible materials like copper and aluminium, or they may be "tin" or galvanized steel. In some cases, small sheets or strips may be soldered at lapped joints to form continuous membranes of large area; on sloped roofs, the batten type may be used. They should, however, be fastened down securely to prevent vibrating in the wind, or even being ripped off, and they should be provided with frequent contraction joints so that they will not be ruptured by tensile stresses produced by low temperatures. For this, vertical ribs or soldered, upstanding joints are suitable if planned so as to avoid interference with drainage. Nails holding down copper roofing should be copper also in order to render long service.
d. Shingles. These may be made of wood, slate, bituminous material, asbestos-cement, or even terra-cotta tile. Since they are laid with staggered joints and large laps that, of themselves, are not watertight, they are for use on sloping roofs only. Because of the sizes and types of industrial structures, shingles are not used extensively except for minor buildings.
e. Corrugated Sheets. These may be copper, aluminium, galvanized iron or steel, asbestos-protected metal, or transite. Unlike the materials previously described, corrugated roofings need not be laid on some form of sheathing or supporting medium; they are designed to span from one purlin to another. Since the joints between adjacent sheets are lapped but seldom made watertight, these sheets are basically a sort of shingle, and hence should not be used on roofs having a slope of less than about 3:12 unless the laps are cemented. The fastenings must be firm and durable, and the structure should be so designed that workmen can get at the connections to install them properly
In the case of any of the preceding roofings, except corrugated sheets, it is important to provide a strong, stiff support (sheathing) so that deflections under load will not be harmful. For example, if wooden sheathing is used under a built-up bituminous roofing, or even under a sheet-metal one, the boards or planks should be tongued-and-grooved so that*, when a man steps on one board, it will not deflect while its neighbor remains stationary, thereby tending to rupture or loosen the roofing. It is also important to make sure that shrinkage of wooden sheathing, deflections of abutting beams, and movement of expansion joints will not cause the roofing to rip apart.
(3900 signs)
* Prefabricated "Pilot" or Other Bituminous Roofing Papers - готовый кровельный толь “Pilot” или другие сорта толя.
* The boards or planks should be tongued-and-grooved so that - доски или планки должны быть соединены в шпунт, так что...