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Discuss, using notes and freehand sketches, three functional requirements of an external wall suitable for a new dwelling house - Leaving Cert Construction Studies - Question 4 - 2017
Question 4
Discuss, using notes and freehand sketches, three functional requirements of an external wall suitable for a new dwelling house. (b) When specifying a high performa... show full transcript
Worked Solution & Example Answer:Discuss, using notes and freehand sketches, three functional requirements of an external wall suitable for a new dwelling house - Leaving Cert Construction Studies - Question 4 - 2017
Step 1
Discuss, using notes and freehand sketches, three functional requirements of an external wall suitable for a new dwelling house.
Answer
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Thermal Insulation: An external wall must minimize heat loss in winter and maintain a cool environment in summer. This is achieved through materials with high thermal resistance, such as insulated concrete forms or dense timber frames. Adequate insulation, such as cavity wall insulation, must be included to reduce thermal bridging and improve energy efficiency.
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Moisture Control: The wall should prevent moisture ingress from rain or humidity, protecting the internal environment and structure. Solutions involve the use of moisture-resistant materials, proper flashing, and drainage systems to filter moisture away from the building fabric.
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Structural Integrity and Robustness: The wall must provide structural support, resisting external loads and forces such as wind, snow, and seismic activities. This can be ensured through adequate wall thickness, reinforcement, and the use of strong building materials.
Step 2
When specifying a high performance external wall for a new house, a choice is to be made between: - a rendered cavity wall of concrete block construction or - a wall of timber frame construction with a rainscreen of cedar cladding, as shown or - a rendered wall of timber frame and hemp-lime construction.
Answer
1. Rendered Cavity Wall of Concrete Block Construction
- Components:
- Inner block layer
- Cavity space for thermal insulation
- Outer rendered layer
- Typical Dimensions:
- Blocks: 440mm x 215mm x 100mm
- Cavity: 50mm
2. Timber Frame Construction with Rainscreen of Cedar Cladding
- Components:
- Timber stud frame
- Insulation within the frame
- Rainscreen of cedar cladding
- Weather-resistant barrier
- Typical Dimensions:
- Timber studs: 90mm x 45mm
- Cedar boards: 25mm x 150mm
Step 3
Discuss the construction of each wall type selected under the following headings: - environmental considerations - ease of construction.
Answer
Rendered Cavity Wall of Concrete Block Construction
Environmental Considerations:
- Positives: Durable materials resist moisture and require less maintenance, thus reducing resources over time. Concrete blocks also utilize raw materials efficiently.
- Negatives: Heavy material may have a high carbon footprint during transport and assembly. Proper handling is necessary to limit material waste.
Ease of Construction:
- Straightforward assembly with available skilled labor. Standard sizes of blocks facilitate quick construction.
- Requires careful planning for insulation placement and moisture barriers.
Timber Frame Construction with Rainscreen of Cedar Cladding
Environmental Considerations:
- Positives: Utilizing sustainable timber reduces carbon emissions. The design allows for effective rainwater management, minimizing surface runoff.
- Negatives: Timber requires regular maintenance and can be susceptible to decay if poorly managed.
Ease of Construction:
- Faster construction time due to lightweight materials. Standard timber sizes and prefabricated elements simplify the assembly process. However, requires skilled labor for precise installation and finishing.