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The sketch shows portion of the eaves of a flat roof - Leaving Cert Construction Studies - Question 5 - 2018
Question 5
The sketch shows portion of the eaves of a flat roof. The roof is covered with layers of bituminous felt, on a 20 mm plywood deck, on battens, on sloping firring pie... show full transcript
Worked Solution & Example Answer:The sketch shows portion of the eaves of a flat roof - Leaving Cert Construction Studies - Question 5 - 2018
Step 1
Draw a vertical section through the eaves of the flat roof and through the external wall.
Answer
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Begin with the base, illustrating the 400 mm concrete block wall and the external rendered finish. Ensure to detail the full-fill insulated cavity within the wall.
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Above the wall, draw the 100 mm wallplate, ensuring it's tied to the blockwork with wallplate straps.
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For the roof structure, depict the 200 mm x 50 mm roof joists supported on the wallplate, showing the layout every 500 mm apart.
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Include the 18 mm plywood decking on top of the roof joists, along with 3 layers of bituminous felt, indicating the waterproofing system.
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Represent the batten system (50 mm x 50 mm) and the sloping firring pieces that create a slope of 1:40 for drainage.
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Indicate a breathable roofing membrane over the plywood decking, and detail the insulated plasterboard ceiling below the joists, with a thickness of 12.5 mm.
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Make sure to annotate three typical dimensions on the drawing, ensuring readability and clarity.
Step 2
On your drawing show how the flat roof is ventilated at the eaves.
Answer
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Integrate vents into the soffit of the design to allow air to flow into the flat roof space.
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Show cross battens along the eaves that will enable air circulation freely beneath the roof construction.
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Ensure to label the ventilation system clearly, indicating how airflow will enter through the soffit and over the insulation layer.