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The sketch shows portion of the roof and external wall of a single-storey dwelling house - Leaving Cert Construction Studies - Question 1 - 2014
Question 1
The sketch shows portion of the roof and external wall of a single-storey dwelling house. The house has an internal span of 6.0 metres. The external wall is of timbe... show full transcript
Worked Solution & Example Answer:The sketch shows portion of the roof and external wall of a single-storey dwelling house - Leaving Cert Construction Studies - Question 1 - 2014
Step 1
To a scale of 1:10, draw a vertical section through one external wall and one rafter length.
Answer
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Setup the Drawing: Begin by establishing the scale of 1:10 on your drawing surface. This will allow you to accurately depict the dimensions of the section.
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External Wall Details: Draw the external wall showing the rendered concrete block outer leaf, the timber frame inner leaf (200 mm), and the 60 mm insulated service cavity. Include accurate dimensions for all elements.
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Rafter Length: Create a rafter representation showing the prefabricated trussed rafters pitched at 30 degrees. Detail the intersection with the external wall.
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Ceiling Joists: Illustrate the ceiling joists, making sure to reference the 400 mm distance below them as specified. Ensure the connection to the wall is evident.
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Eaves and Ventilation Path: Indicate the eaves and add details for the ventilation path leading to the roof. It's essential to show how air flows and where ventilation components are positioned.
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Three Courses of Slate: At the eaves, depict three courses of slate with proper lapping to illustrate waterproofing. Label the courses and show how they rest on the underlying structure.
Step 2
Indicate clearly the design detailing to ensure airtightness at the junction of the ceiling and the external wall.
Answer
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Sealing the Junction: Ensure that there are airtight materials used at the junction, such as continuous vapour barriers between the ceiling and external wall.
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Use of Insulation: Incorporate insulation materials that are sealed around the junction to prevent air leakage. For example, using 12 mm OSB or plywood with taped joints can enhance airtightness.
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Gasket Material: Apply gasket or compressible materials to fill gaps around the junction effectively. This should be done to combat air movement and improve energy efficiency.
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Skim Finishing: Upon completing the structural work, maintain a skim finish along the joint to cover any irregularities that may allow air to escape.
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Inspection Points: Designate areas for inspection to ensure that the airtight features have been substantiated during construction. This allows for adjustments and testing post-installation.