Definition and function of foundation JS 3 (BASIC 9) BASIC TECHNOLOGY SECOND TERM WEEK 7
SECOND TERM: E-LEARNING NOTES
JS 3 (BASIC 9)
SUBJECT: BASIC TECHNOLOGY
SCHEME OF WORK
WEEK: SEVEN
DATE:
TOPIC: BUILDING
SUB-TOPICS:
- Definition and function of foundation
- Types and materials for making walls
Content Development (NOTES FOR FIRST LESSON/PERIOD ONE)
sub-Topic I: Definition and function of foundation
Foundation.
The term foundation is the expanded base of a column in addition to the ground or sub-soil which supports the base. The ground or sub soil on which the building stands is the natural foundation, while the expanded base which is constructed of concrete or mansory materials like rocks, stones, bricks is called artificial foundation. The choice of foundation depends on the type of building to be constructed, the load imposed on the building and the type and nature of the soil.
Functions of foundation:
1. To receive the weight of the building.
2. To distribute the weight of the building to the ground effectively.
3. To hold the building firmly to the ground against external forces like wind, storms.
4. To transmit the weight of the building to the sub-soil or ground.
5. To sustain the dead load of the building.
Types of foundation:
1. Strip foundation: This consists of a continuous strip of concrete laid on the trench after excavation. It is usually 225mm thick and used for bungalows, fences etc and on a moderately hard soil.
2. Pad foundation: This type of foundation is an isolated foundation used to support columns. The size of the pad foundation could be reduced by providing steel reinforcement towards the bottom of the foundation running in both directions. It is used for storey building.
3. Raft foundation: This is used where the load bearing capacity of the soil is weak. It is used on sandy, swampy or marshy ground. It consists of reinforcement slab up to 300mm thick. It covers the whole area of the building and usually extends beyond it.
4. Piled foundation: This is used for multistory buildings, for supports in bridges and water logged areas to support the structures. The imposed load is transmitted to suitable materials in a lower stratum by the use of piles.
TYPES OF SOIL AND THEIR PROPERTIES
| S/N | TYPE OF SOIL | PROPERTIES |
| 1 | Sand | The particles are gritly to finger, loose, easily break when dry |
| 2 | Clay | Easily moulded, brittle and tough when dry, sticky when wet. |
| 3 | Gravel | It is loose, easily removed by shovel and homogenous |
| 4 | Silt | Dries quickly, moderately plastic, soft and firm, homogenous |
Excavation for foundation: This is the process of digging the ground to the required depth not less than 750mm. There are two basic methods of excavation.
1. Manual method: This involves the use of digger, shovel, wheelbarrow
2. Mechanical method: This involves the use of mechanically operated machine e.g excavation tractor, mechanical shovel, ditcher etc
EVALUATION
1. What is foundation?
2. Mention three reasons why it is necessary to construct foundation.
3. Under what conditions are the different types of foundation used?
Content Development (NOTES FOR SECOND LESSON/PERIOD TWO)
Sub-Topic II: Types and materials for making walls.
Wall: It is a structural member in building(450mm) used mainly for the enclosure or division of a space within a building. It canbe external wall or load bearing wall built right from the foundation to the roof level, it carries the weight of itself and some other elements e.g roof.
It can be internal cross walls, they are the non-load bearing wall(150mm), it carries only the weight of itself.
Function of a wall:
i. To carry the load and other elements in the building structure.
ii. To divide a space as partition and as a compartment wall.
iii. To protect the structure against weather.
iv. For privacy
v. For security purpose
Walling Materials: They include stone, clay and mud, Timber, Bricks, sand creates blocks etc.
Types of walls: There are many types of walls, depending on the materials used and the method of construction.
i. Block wall ii. Partition wall iii. Sleeper wall iv. Timber wall v. Foundation wall vi. Glass wall vii. Retaining wall viii. Cavity wall ix. Reinforced concrete walls x. Stone wall xi. Bamboo wall xii. Clay or mud wall xiii.Masonry wall.
WALL FINISHES: They are materials used to protect the surface of a wall from weather element. The common wall finishing are Plastering, rendering and painting.
Plastering: This is the type of finishing that is given to the internal wall of a building. Cement and sand are mixed with water in ratio 1:3 with the help of hand Trowel. Two or three layers of plastering are recommended on the surface of a masonry wall.
Rendering: This is the type of finishing that is given to the external wall of a building. This can be done using
i. Mixture of cement, sand and water and applied to the surface of the wall with hand trowel.
ii. Pebble dash: This is done by throwing about 10mm size of gravel on the surface of the external wall.
iii. Spattered dash finish: This is done by spraying about ratio 1:6 (cement and sand ratio) mixture containing colored pigment on the surface of the wall.
Painting: This is a liquid coating applied on the surface of a building wall for the purpose of decoration and protection from the elements of weather.
BONDING: This refers to the arrangement of bricks or blocks in a way that a brick or block rests on at least 2 others so that continuous vertical joint which reduces strength and stability in walls is eliminated.
EVALUATION:
- Mention three functions of a wall.
- Mention four materials for walling
- List five types of wall.
WEEKEND ASSIGNMENT:
Within your locality get the different types of soil and write out their composition, structure and profile
