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The roof of a new house, as shown, is a traditional cut roof and has a pitch of 45 degrees - Leaving Cert Construction Studies - Question 7 - 2015
Question 7
The roof of a new house, as shown, is a traditional cut roof and has a pitch of 45 degrees. The house has an internal width of 6.0 metres and the roof is highly insu... show full transcript
Worked Solution & Example Answer:The roof of a new house, as shown, is a traditional cut roof and has a pitch of 45 degrees - Leaving Cert Construction Studies - Question 7 - 2015
Step 1
To a scale of 1:10, draw a vertical section through one half of the roof structure from eaves up to ridge, showing one external wall and one rafter length.
Answer
To begin, set the drawing scale to 1:10. Start from the eaves and draw a vertical section of the cut roof, illustrating the following elements:
- Rafters: Include 225 mm x 40 mm timber rafters at a 45-degree angle.
- Wall: Draw the 400 mm concrete block wall, ensuring it is correctly positioned to support the rafters.
- Insulation: Detail the insulated plasterboard beneath the rafters and the 200 mm insulation above it.
- Floor Joists: Depict the 225 mm x 40 mm floor joists lying flat across the top of the wall, supported centrally.
- Slate Roof: Represent three layers of slates at the roof eaves.
- Dimensions: Include dimensions using hatching or textual annotations for at least four key structures, such as the height from floor to ridge, width of the wall, height of the eaves, and thickness of insulation.
Remember to maintain clarity and ensure that each component is accurately represented.
Step 2
Include on your drawing, best practice design detailing to ensure ventilation of the roof structure.
Answer
For effective roof ventilation, incorporate the following details in your drawing:
- Vents: At the eaves and ridge, indicate the installation of continuous vents to allow air circulation. These should facilitate the entry of fresh air at the eaves and the expulsion of warm, moist air at the ridge.
- Breather Membrane: Depict a breather membrane that wraps around the rafters, ensuring moisture does not accumulate. This membrane must be appropriately taped at seams.
- Air Space: Clearly show the air space between the insulation and the roof covering. This gap promotes airflow and minimizes condensation.
- Soffit Ventilation: Add soffit vents to allow cool air to flow into the roof space, promoting a balanced ventilation system.
- Insulation Layout: Ensure insulation is placed in a manner that does not block the airflow, specifically at points near the eaves.
By following these best practices, you can effectively illustrate a roof design that minimizes moisture-related issues.