Science & Technology in Action

8th Edition

The Building Envelope

CRH

In the case of a house, the building envelope consists of a floor, foundations, walls and a roof; openings are usually provided in the walls for doors, windows and air vents. In this lesson we will look at the materials used to construct the main elements of the building envelope.
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Contains the full lesson along with a supporting toolkit, including teachers’ notes.

Lesson excerpt

A building is a structure designed to protect humans, animals and property from the effects of weather. The building envelope is the outer layer or shell of a building. In the case of a house, it consists of a floor, foundations, walls and a roof; openings are usually provided in the walls for doors, windows and air vents. The building envelope is the barrier between the internal space and the external and so provides shelter from environmental factors such as wind and rain. The structure is self-supporting and sufficiently strong to withstand normal variations of weather and it should provide an internal environment that is different from that outside.

In this lesson we will look at the materials used to construct the main elements of the building envelope — the walls and roof. Among the earliest building materials were mud, stone and wood. Concrete is a more recent invention and its general use for construction of houses dates from the early 1900’s.

Mud
Mud on its own is not very strong but when reinforced with fibrous material, such as straw, it can be used to construct surprisingly large and durable buildings. It is inexpensive, easy to work with and requires little or no specialist equipment. It can be formed into bricks that are then left to dry in the sun, typically for a few weeks. Alternatively mud can be plastered onto a wicker framework (wattle) which holds it in place while it dries and hardens. Mud can also be used to construct roofs if it is formed into a dome, arch or conical shape; vents are usually formed at the top. Mud buildings are common today in many parts of the world; about half the world’s population still live or work in buildings made of clay, mud or mud bricks. Mud buildings were widely used in rural Ireland well into the last century.

Quiz questions

  1. People have been using concrete for over 10,000 years. false
  2. Cement is the same thing as concrete. false
  3. About half the world’s population today live in houses made of clay or mud true
  4. It is possible to construct a roof with mud. true
  5. Wood used in construction is effectively a ‘carbon sink’. true
  6. Compressive strength is measured in pascals or megapascals. true
  7. Lime is made by calcining limestone. true
  8. When concrete sets it turns into calcium carbonate. false
  9. The ancient Romans used Portland cement. false
  10. The chemical formula for calcium carbonate is Ca(OH)2. false

Glossary of terms

clay
tension
partition
calcining
compression

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