principles of construction/ foundations/18-19

2.  Aim:
 Introduce learners to selecting foundations.
 Objectives:
 List the different types of foundations used on houses.
 List the foundations used on commercial buildings.
 Describe factors to be considered when selecting foundations.
 Explain how foundations are laid/installed.

3.  There are three main types of foundations used within construction:

4.  There are three main types of foundations used within construction:
• strip and wide strip
• raft
• piled.

5.  Strip foundations are arguably the cheapest form of foundation available to designers
and constructors.
 Strip foundations involve the removal of a strip of land to a set depth and width.
Concrete is then poured into the strip/trench and tamped level.
 Strip foundations can only be used on firm, good bearing strata, and to a depth of no
more than 1.5-2m to be economical.

6. Step 1.
Step 2.
Step 3.
Step 4.

7.  Strip foundation – with reinforcement

8.  Raft foundations are often used where
• For example, if you were to
poke your fingers into sand
they would sink to a certain
depth. However if you were to
hold your hand flat across the
same sand, the sand would
offer more resistance because
the load is applied across a
greater area. This is the
principal of a raft foundation.