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The sketch shows a dwelling house with a traditional slated cut roof - Leaving Cert Construction Studies - Question 1 - 2020
Question 1
The sketch shows a dwelling house with a traditional slated cut roof. The roof has a pitch of 30° and flush eaves as shown. The internal span of the house is 6.0 met... show full transcript
Worked Solution & Example Answer:The sketch shows a dwelling house with a traditional slated cut roof - Leaving Cert Construction Studies - Question 1 - 2020
Step 1
To a scale of 1:10, draw a vertical section through one half of the roof structure from just below eaves up to ridge.
Answer
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Start by drawing the outline of the house walls. Ensure the external wall dimensions include a total thickness of 215 mm.
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Next, add a rafter at a pitch of 30°. For a 6.0 m internal span, calculate the height using basic trigonometry as follows:
= 3.0 \times 0.577 \approx 1.732 m$$ -
Include key details visible in the section: the insulated plasterboard fixed to the underside of the ceiling, the service cavity of 50 mm, and the external insulation.
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Draw the three courses of slate starting from the bottom edge of the roof structure ensuring to show the overlap of slates and how they are fixed.
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Label all components clearly, including wall and roof dimensions such as: 600 mm up to the ceiling joists, dimensions of the rafters, and eaves details.
Step 2
On your drawing, show the typical design detailing to ensure ventilation of the roof structure.
Answer
- Indicate the location of ventilation openings at the eaves level, showing how the airflow will enter the roof space. Typically, these can be proprietary vents or openings in the fascia.
- Draw vertical ventilation channels allowing airflow from the eaves to the ridge. This is essential to avoid condensation issues.
- At the ridge, show the installation of a ridge vent that allows hot air to escape.
- Illustrate the breathable membrane underneath the roof tiles to facilitate air flow, ensuring proper detailing at junctions with insulation material to avoid bridging.
- Label all ventilation components clearly including dimensions of the vents and the ridge opening.