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The sketch shows one corner of a strip foundation for the external wall of a dwelling house - Leaving Cert Construction Studies - Question 4 - 2018
Question 4
The sketch shows one corner of a strip foundation for the external wall of a dwelling house. The external wall is to be a 400 mm concrete block wall with a full-fill... show full transcript
Worked Solution & Example Answer:The sketch shows one corner of a strip foundation for the external wall of a dwelling house - Leaving Cert Construction Studies - Question 4 - 2018
Step 1
Discuss one environmental reason why a strip foundation is considered the most suitable foundation for this house.
Answer
A strip foundation is considered environmentally beneficial as it minimizes ground disturbance. This method requires only minimal excavation, which helps preserve the natural landscape and reduces the carbon footprint associated with extensive machinery use. Additionally, by using less concrete and materials in construction, strip foundations have a reduced environmental impact compared to more complex foundations.
Step 2
Using notes and freehand sketches describe how to set out the foundation trench under the following headings: profiles.
Answer
The profiles for the foundation trench consist of two upright members connected by a horizontal cross rail. The setting out of the foundation is carried out to ensure that the foundation aligns correctly with the building's dimensions. The datum point is established and secured to ensure accuracy. A level is used to maintain consistent height, and a laser or optical level may be employed for increased precision.
Step 3
Using notes and freehand sketches describe how to set out the foundation trench under the following headings: width and depth of trench.
Answer
The trench width is typically marked based on the wall specifications. For instance, if the wall width is 400 mm, the trench is generally set to accommodate this while allowing for a minimum depth, which is usually around 500 mm. The depth of the trench also depends on the type of soil and frost line considerations to prevent structural issues.
Step 4
Using notes and freehand sketches describe how to set out the foundation trench under the following headings: position of wall on strip foundation.
Answer
The wall should be positioned centrally on the strip foundation to ensure even load distribution. Lines are stretched from the profiles to establish the correct placement. It’s crucial to check the position with respect to the foundation’s dimensions to maintain structural integrity. The wall's width should be verified before finalizing its location.
Step 5
Using notes and freehand sketches, show how to determine the top surface of the foundation prior to placing the concrete to ensure that the foundation is level throughout.
Answer
To determine the top surface of the foundation, a series of pegs should be placed around the perimeter of the trench at the desired height. A leveling instrument is utilized to ensure that points A and B are at the same required level. After establishing these reference points, a string line can be used to align additional pegs, ensuring that the top surface will be consistent across the entire foundation area. This method guarantees a level surface before concrete placement.