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A two-storey house, as shown in the drawing, is of timber frame construction with a rendered concrete block outer leaf - Leaving Cert Construction Studies - Question 9 - 2013
Question 9
A two-storey house, as shown in the drawing, is of timber frame construction with a rendered concrete block outer leaf. The chimney is also of rendered concrete bloc... show full transcript
Worked Solution & Example Answer:A two-storey house, as shown in the drawing, is of timber frame construction with a rendered concrete block outer leaf - Leaving Cert Construction Studies - Question 9 - 2013
Step 1
Select any three locations from those circled on the drawing and show, using notes and freehand sketches, the typical design detailing which will prevent the penetration of dampness at each location.
Answer
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Location 1: Lead Back Gutter Welded Under Slate
- Lead is wrapped around the chimney to prevent moisture penetration.
- Roof membrane is carried under battens and secured to the chimney using proprietary tape.
- Cover flashing is applied at the back of the chimney to overlap the lead gutter.
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Location 2: Weather Strip at Top of Window
- A stepped damp-proof course (DPC) ensures moisture does not penetrate to the inside leaf.
- An anti-capillary groove is integrated at the sash opening.
- Mastic sealant is applied around the window to prevent driven rain from reaching the inner leaf.
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Location 3: Cavity Wall with Inner Leaf
- The cill is wrapped in DPC to prevent moisture from the cavity.
- A second layer of DPC is incorporated into the cill design.
- Mastic sealant is applied around the window opening to ensure airtight sealing.
Step 2
Select any two junctions and specify a damp-proofing material suitable for each junction. Discuss the advantages of each material for the specified junction.
Answer
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Junction 1: Chimney to Roof
- Material: Lead
- Widely used around chimneys and is flexible, accommodating moderate movement without compromising effectiveness.
- Resistant to corrosion, ensuring longevity and durability in preventing dampness.
- Material: Lead
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Junction 2: Wall to Roof Junction
- Material: Flexible Plastic DPC
- Readily available and typically more cost-effective.
- It effectively prevents moisture ingress and can easily be shaped to fit various junction designs.
- Material: Flexible Plastic DPC
Step 3
Discuss in detail the importance of ensuring that moisture does not penetrate to the inner leaf of a wall of timber frame construction.
Answer
Preventing moisture penetration is critical for several reasons:
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Ensures Prolonged Life of Timber Frame
- Moisture can lead to rotting, adversely affecting the structural integrity of timber, which may compromise safety.
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Avoids Damp Issues
- If internal walls become damp, it can result in mold growth, which poses health risks to occupants.
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Preservation of Insulation Properties
- Dampness can reduce the effectiveness of insulation materials, resulting in increased energy costs.
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Sealing Techniques
- Proper sealing and detailing at junctions ensure that all brickwork is pointed correctly and utilize breather membranes to effectively manage moisture.
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Construction Best Practices
- Keeping damp materials like masonry away from wooden elements is essential, as well as maintaining airtight seals to prevent moisture accumulation.