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A front porch with a flat roof projects 1.5 metres from the external wall of a house, as shown - Leaving Cert Construction Studies - Question 1 - 2016
Question 1
A front porch with a flat roof projects 1.5 metres from the external wall of a house, as shown. The roof of the porch is insulated, and is covered with layers of bit... show full transcript
Worked Solution & Example Answer:A front porch with a flat roof projects 1.5 metres from the external wall of a house, as shown - Leaving Cert Construction Studies - Question 1 - 2016
Step 1
(a) To a scale of 1:5, draw a vertical section through the porch
Answer
To draw the vertical section through the porch:
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Outline the Structure:
- Start by sketching the external wall of the house to the left, then project 1.5 meters outward to illustrate the porch roof. Mark the depth of the porch and extend the external wall up to the flat roof level.
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Draw the Porch Roof:
- Indicate the flat roof above the porch with the specified bituminous felt layers. Use lines to represent each layer, ensuring to denote the plywood decking and joists beneath.
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Include Window Details:
- Position the triple-glazed window on the porch wall, ensuring it's accurately sized relative to the porch dimensions. Add a thermal break in the window frame.
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Construction Details:
- Show the roof joists and their connection to the insulated plasterboard. Indicate how the insulation fits within the cavity of the wall.
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Dimensions:
- Include four critical dimensions, such as the height of the window from the floor, the height of the roof above the external wall, and the vertical distance from the bottom of the window to the bottom of the porch.
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Labeling:
- Clearly label each part of the structure including the wall, roof, window, and insulation details.
Step 2
(b) Show on your drawing the design detailing to prevent the ingress of water
Answer
To prevent the ingress of water at the junction:
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Flashing Details:
- Indicate a lead flashing that extends from the edge of the flat roof down to the external wall. This will direct water away from the junction.
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Vapor Control Layer:
- Include a vapor control layer under the asphalt and on top of the insulation, ensuring it overlaps the top of the wall.
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Slope and Drainage:
- Sketch a slight slope on the flat roof towards the drainage point to encourage water runoff away from the junction.
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Sealant Application:
- Show sealant being applied around the perimeter of the flashing and along the wall junction to create a watertight seal.
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Installation of Gutters:
- Include gutters or drip edges as a secondary measure to collect and channel runoff water away from the junction.