Lesson Notes By Weeks and Term - Junior Secondary School 2

SUBJECT:  BASIC TECHNOLOGY       

CLASS:  JSS2

DATE:

TERM: 3RD TERM

REFERENCE MATERIALS 

• MELROSE, Basic Science and Technology Book 2
• NERDC, Basic Technology for JSS, Book 2

WEEK EIGHT

TOPIC: SETTING OUT

Anybody wishing to construct a building usually first consult an architect on the need for a building and the type of building wanted. An architectural design is sent to the structural engineer, who determines and specifies the strength and type of building material to be used. The quantity surveyor studies the working drawing of the proposed building determines the cost of materials, labour and workmanship. Finally, a construction company wins the contract for the construction of the building.

SETTING OUT

Building construction start with setting out

Setting out is, therefore, a process of driving wooden pegs into the ground here and there, in a manner that agrees with the dimensions of the building specified on the architect’s drawings.

Setting out is also the process of transferring with high degree of skill and accuracy, the detail of the foundation plan from the drawing sheet on the ground, with pegs, lines and tapes.

Working drawings include following drawings:

1. The floor plan
2. The elevations
3. The sections
4. The detailed drawing
5. The schedules 
6. The electrical plan 
7. The plumbing plan

The following tools are used for setting out 

1. Steel rule
2. Builder’s square
3. Theodolite

When the concrete footing for the foundation has been cast and cured lines for the thickness of the wall are run and plumbed down to the concrete footing and the first course of the concrete block wall is laid.

EVALUATION

1. What is setting out?
2. Mention the tools used for setting out

EXCAVATION

When foundation plan for a building has been transferred on to the site, by way of setting out, excavation begins. For very big structures like stadium or a multi-storey building, the trenches for the column foundation or wall foundation can be mechanically excavated. Holes are mechanically bored where bored piled foundation has been recommended.

TIMBERING

This is the process of supporting the walls of the excavated pit with timber, for the purpose of safety.

CONCRETE AND ITS MATERIALS

Concrete consists of a matrix or binding material (cement), fine aggregate (sand) and coarse aggregate (stone) mixed thoroughly with water. Concrete, therefore, is a composite material in which a binding material mixed with water o solidification binds the inert materials – the particles of well- graded fine and coarse aggregates. Green concrete is used in the construction of footings, foundations, slabs, columns, lintels, beams, steps, and walls. It resists decay moisture and corrosion from acids. REINFORCED concretes are concrete having steel rods or welding wire mesh.

A good concrete should be strong, durable, hard, dense, non-porous, fire resisting and economical.

EVALUATION QUESTIONS

1. Define (a) Excavation (b) Timbering
2. Mention the materials used for making cement.

GENERAL EVALUATION

1. Define the following a) excavation    b)timbering (c) setting out
2. Mention things involve in working drawings.

READING ASSIGNMENT

Read more on setting out (NERDC Basic Tech. for JSS2 page123-126 )

WEEKEND ASSIGNMENT

1. The process of supporting the walls of the excavated pit with timber (a) excavation (b) timbering (c) concrete (d) coarse aggregates
2. Which of the following is not used for setting out right-angled triangles and squaring (a) steel square (b) builder’s square (c) concrete  (d) Theodolite
3. Which of the following is not a required expectation of a good concrete (a) strong and hard (b) durable and fire resisting (c) non-porous and economical (d) weak and poor
4. The process of transferring with high degree of skill and accuracy, the details of the foundation plan from the drawing sheet on to the ground with pegs, lines and tape. (a) Timbering (b) working drawing (c) setting out (d) site preparation
5. Which of the following professional plans and designs a building that satisfies the wishes and needs of the client? (a) Quantity surveyor (b) structural engineer (c) architect (d) plumber

THEORY 

1. Define (a) setting out (b) timbering  (c) excavation
2. State and discuss six (6) working drawings used by building worker.