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Discuss in detail, using notes and freehand sketches, three functional requirements of a roof suitable for a dwelling house - Leaving Cert Construction Studies - Question 2 - 2011
Question 2
Discuss in detail, using notes and freehand sketches, three functional requirements of a roof suitable for a dwelling house. Using notes and freehand sketches, show... show full transcript
Worked Solution & Example Answer:Discuss in detail, using notes and freehand sketches, three functional requirements of a roof suitable for a dwelling house - Leaving Cert Construction Studies - Question 2 - 2011
Step 1
Discuss in detail, using notes and freehand sketches, three functional requirements of a roof suitable for a dwelling house.
Answer
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Weather Resistance: A suitable roof must be able to protect the building from various weather conditions, including rain, snow, wind, and sun. This prevents water ingress and ensures the longevity of the structural elements beneath.
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Structural Stability: The roof must be designed to support all imposed loads, including dead loads (the weight of the roof structure itself) and live loads (such as snow accumulation). The design should follow engineering principles to ensure it can hold these loads safely.
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Durability: The roof structure should be long-lasting with low maintenance needs. Using high-quality materials, proper insulation, and protective coatings can enhance durability and reduce the need for repairs over time.
Step 2
Using notes and freehand sketches, show two different types of pitched roof structure suitable for a dwelling house having an internal span of 6.0 metres and one internal load-bearing wall.
Answer
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Traditional Cut Roof / Purlin Roof:
- Description: This roof type includes rafters and purlins providing support while facilitating ventilation.
- Dimensions:
- Rafter: 200 x 50 mm
- Strut: 125 x 50 mm
- Purlin: 175 x 75 mm
- Structural Stability: The purlin supports the roof load, while the strut aids in transferring loads to the load-bearing wall.
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Prefabricated Roof (W Truss):
- Description: This type employs a truss system based on the principle of triangulation, ensuring stability under loads.
- Dimensions:
- Rafter: 170 x 45 mm
- Compression Web: 120 x 45 mm
- Tension Web: 120 x 45 mm
- Structural Stability: The triangulated design distributes loads effectively, maintaining rigidity and preventing deformation under stress.
Step 3
Recommend a preferred roof structure for a dwelling house and give two reasons in support of your recommendation.
Answer
I recommend the Prefabricated Trussed Roof for a dwelling house.
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Efficiency in Construction: This type of roof is fast and easy to erect, reducing labor time and making it less dependent on weather conditions during construction.
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Structural Integrity: The prefabricated approach ensures precise manufacturing, providing optimal strength and minimizing the risks associated with on-site construction errors. The load distribution mechanisms inherent in the design contribute to its resilience.