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The external wall of a house built in the 1960s is of 215 mm single-leaf hollow block construction - Leaving Cert Construction Studies - Question 2 - 2018
Question 2
The external wall of a house built in the 1960s is of 215 mm single-leaf hollow block construction. The wall is plastered on both sides, as shown. It is proposed to ... show full transcript
Worked Solution & Example Answer:The external wall of a house built in the 1960s is of 215 mm single-leaf hollow block construction - Leaving Cert Construction Studies - Question 2 - 2018
Step 1
Using notes and freehand sketches show one suitable method of applying an external insulation system to the wall. Specify the typical thickness of the insulation.
Answer
One suitable method for applying expanded polystyrene insulation involves a few key steps:
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Installation of the Track: A stainless-steel track is fixed to the external wall at DPC level.
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Placement of the Insulation Boards: The first row of insulation boards (B) is put in place resting on the track. Next, insulation boards are fixed in a staggered pattern to improve thermal integrity.
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Fixing the Boards: The boards are fixed using a special proprietary adhesive (C).
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Number of Fixings: The fixings must be evenly distributed, typically being drilled into the insulation and placed at a required spacing.
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Thickness of Insulation: The minimum thickness of insulation used is 200 mm.
Step 2
On your sketch show clearly the steps to be followed in applying a surface finish to the insulation. Specify the materials to be used for the surface finish.
Answer
The steps to apply a surface finish to the insulation are as follows:
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Filling the Fixing Heads: The heads of the fixings are filled with a base coat of material.
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Applying Base Coat: A base coat of acrylic plaster (S) is applied to the surface of the insulation.
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Applying Reinforcement Mesh: A reinforcing mesh (B) is applied to the wet plaster to enhance durability.
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Preparation for Final Coat: The next coat (C) is applied as a preparation for the final coat.
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Final Coat Application: The final acrylic coat (D) is then applied, which may use a steel trowel for a smooth finish.
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Material Options: Various proprietary finishes are available, including options with a brick effect, offering aesthetic versatility. Maintenance for these finishes usually lasts for 10-15 years.
Step 3
Discuss one advantage and one disadvantage of applying an external system of insulation to the walls of a house.
Answer
Advantage: One significant advantage of applying an external insulation system is that it reduces heat loss through external walls. This leads to lower energy bills and improved energy efficiency ratings for the house.
Disadvantage: On the other hand, a notable disadvantage is the expense associated with adding insulation to the house. Additional costs may arise from changes required to window sills and dealing with maintenance elements such as ensuring that there are no moisture issues.