Photo AI
A strip foundation is designed to support a 350 mm external wall of a dwelling house - Leaving Cert Construction Studies - Question 4 - 2012
Question 4
A strip foundation is designed to support a 350 mm external wall of a dwelling house. The wall is of concrete block construction with an insulated cavity, as shown i... show full transcript
Worked Solution & Example Answer:A strip foundation is designed to support a 350 mm external wall of a dwelling house - Leaving Cert Construction Studies - Question 4 - 2012
Step 1
width and depth of trench
Answer
The minimum width of the foundation should be three times the thickness of the wall, so in this case it should be at least 1,050 mm for a 350 mm wall. The depth of the trench should be determined by the type of ground and must be at least 600 mm deep to ensure stability. Additionally, the bottom of the trench must be below the frost line to avoid problems associated with freezing.
Step 2
finished level of concrete in foundation
Answer
Wooden or steel pegs are typically driven into the base of the trench to indicate the finished level of concrete. The top of these pegs should project above the base of the trench by a height equivalent to the thickness of the foundation layer. A straight edge or laser level can be used to ensure the tops of the pegs are level.
Step 3
reinforcement of foundation
Answer
Mild steel reinforcing bars should be placed near the bottom of the trench, approximately 75 mm from the bottom for adequate tensile strength. The concrete should be poured, vibrated, and compacted around the reinforcing steel to ensure a strong bond. Additional steel mesh reinforcement may also be incorporated depending on structural requirements.
Step 4
Step 5
Discuss two environmental reasons why a strip foundation is the preferred foundation type for the external wall of the house.
Answer
-
Uses less concrete than raft foundation: Strip foundations typically require less material compared to other foundation types, making them more resource-efficient.
-
Environmentally sustainable: Because they use less energy in materials and construction processes, strip foundations represent a more sustainable choice. They also reduce the overall carbon footprint in terms of building projects.