II. Read the following text
Roofs
A roof is the top covering of a building that sheds rain or snow, keeping the building interior dry. Roofs may be 'pitched', 'domed', 'low slope' or 'flat' in form; however, roofs are rarely truly flat. Flat roofs are commonly found on industrial/commercial type structures while low slope is found on pre-fabricated or steel structures. Pitched roofs are the primary design found on residential homes. The most common type of flat roof for industrial/commercial structures are the conventional built-up-roof assembly and protected roof membrane assembly. The most popular roof membranes are the 4-ply, the 2-ply modified bitumen and the single plies such as the elastomeric and thermal plastic, drains provide run off for rain and snow.
Roof shapes and pitches are often the product of design, material constraints and/or climatic considerations. Roof designs in mild climates or where there is little precipitation tend to exhibit flat roofs and drainage at the exterior wall; an example of residential flat roof is that of the adobe construction in the American Southwest. In northern climates where temperatures drop below freezing we see major .charges in both flat roof and pitch roof design. The need for greater thermal resistance will dictate the type of roof design as well as the waterproofing membrane v specification. In areas that have a high accumulation of snow such as Buffalo USA or Montreal Canada a minimum slope of 4 inches in 12 inches (4/12) of roof surface is required. We often see roof pitches that exceed 45 or 50 degrees. Drainage on cold climate roofs is typically installed at interior locations rather than on the exterior wall as we see in the southern climates. By placing the drains toward the interior freezing of the rainwater leader is avoided. Weight of accumulated snow has been known to cause major damage to structures, freeze thaw cycling plays havoc on the flat roof assembly as well as the pitch roof design. Migrating water during thaw periods enters voids then freezes and expands. Daily repetitions of this cycling effect eventually causes damage to the shingle and/or membrane.
III. Answer the questions.
1 . What is the function of a roof?
2. What types of roofs do you know?
3. Where are flat roofs commonly found?
4. What can you say about pitched roofs?
5. Why is it important to consider the climate conditions in roof design?
IV. Complete the statements.
1 . Roof shapes and pitches depend on ...
2. In northern climates the type of roof design will be influenced by ...
3. A minimum slope of 4 inches in 12 inches (4/12) of roof surface is required in ...
4. Migrating water during thaw periods causes damage to the shingle and membrane as ...
V. Read the following text.
Buildings are designed so they are capable of performing the design requirements. The most important design requirements include the following:
A. Weather resistance - keep out wind, dust and precipitation.
B. Privacy - provide visual screening.
C. Surface - provide the surface for activity.
D. Security - keep out intruders.
E. Fire resistance - prevent fire from the spreading.
F. Structure – resist loads.
G. Thermal insulation - modify the passage of heat.
H. Sound insulation - control sound transmission.
J. Moisture - control the passage of moisture.
VI. A) complete the table
| element | main functions |
| floor external wall internal wall roof |
B) Use the table to make statements like the following:
The function of lowest floor includes providing surfaces for activities.
C) Look at the examples:
- The roof and the external walls are designed to resist loads.
- The external wall acts as a thermal insulator.
- The partition enables the building to provide visual screening.
Now answer these questions:
a) What enables the occupants?
- to keep dry
- to have privacy
- to keep warm
- to be safe from fire
b) What elements are designed?
- to control the noise level
- to support snow loads
- to resist moisture
c) What elements act as?
- a thermal insulator
- a sound insulator
-a filter to separate the internal space from the external environment.
VII. Read the text