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The owner of a house built in the 1960s intends to improve the thermal insulation levels by insulating the external walls and the attic space - Leaving Cert Construction Studies - Question 2 - 2010
Question 2
The owner of a house built in the 1960s intends to improve the thermal insulation levels by insulating the external walls and the attic space. The external wall is a... show full transcript
Worked Solution & Example Answer:The owner of a house built in the 1960s intends to improve the thermal insulation levels by insulating the external walls and the attic space - Leaving Cert Construction Studies - Question 2 - 2010
Step 1
Using notes and neat freehand sketches, describe the procedures to be followed when injecting the insulation into the cavity. Specify the type of insulation to be used.
Answer
To inject insulation into the cavity:
- Prepare the Wall: Begin by drilling holes of 22mm diameter at specified intervals (800mm horizontally and 1350mm vertically) into the wall, ensuring there is an access point for the insulation to be injected.
- Create Access Points: Drill extra holes beneath window cells and above door heads to ensure proper filling of the cavity.
- Inject Insulation Beads: Use insulation in the form of polystyrene beads. A professional should perform the injection to ensure the whole cavity is filled.
- Pump the Beads: A light, constant pressure should be applied as the beads are pumped into the cavity. This assists in achieving a uniform fill.
- Finish Holes: After pumping, the holes are sealed and blended with the external finish to maintain aesthetic appearance.
The insulation type used in this process is polystyrene beads.
Step 2
Discuss one advantage and one disadvantage of this method of cavity insulation.
Answer
Advantage: One key advantage of injecting insulation into the cavity is that it significantly reduces heat loss through the walls. This leads to a warmer house, contributing to a higher U-value and lower energy bills for occupants.
Disadvantage: A notable disadvantage is that the cavity may become bridged, which can cause problems in exposed sites. Additionally, damp may travel across the filled cavity, leading to potential moisture issues.
Step 3
Using notes and neat freehand sketches, show how the attic is to be insulated and include the insulation to the water storage tank. Specify the insulation material for the attic and give its typical thickness.
Answer
To insulate the attic:
- Insulation Quilt: Place a quilt (fibreglass) between and over the joists, ensuring proper coverage.
- Layering: Use 100mm of insulation between the joists, with an additional 200-300mm placed at right angles to the joists to enhance thermal efficiency.
- Vapour Barrier: Install a vapour barrier on the warm side of the attic space to prevent moisture ingress.
- Other Insulation Options: Consider using sheep wool, rock wool, or insulated board types for varying insulation needs.
For insulating the water storage tank:
- The tank should be insulated on the sides and top. The insulation should not be placed under the tank to avoid damp issues.
- Typical insulation used could be polystyrene board.
- The insulation thickness for the attic is typically around 100mm for the quilt, with additional thickness for benefits.