Consider the following statements regarding Cavity Walls 1. The primary purpose of a cavity wall is to prevent dampness from the outer face reaching the inner face. 2. The cavity provides better thermal insulation compared to a solid wall of the same thickness. 3. The width of the cavity is usually kept between 10 mm and 20 mm. Which of the statements given above are correct?
- A1 and 2 onlyCorrect
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3
Solution
Concept
Cavity Wall Construction and Properties
Formula
N/A
Step-by-step solution
1. Evaluate each statement regarding cavity wall construction and properties. 2. Identify that statements 1 and 2 are true, while statement 3 is false as standard cavity width is 50 mm to 100 mm. 3. Select Option (a) as the correct choice.
Explanation
Statements 1 and 2 are correct. A cavity wall has an air gap between two leaves, which stops moisture from transferring from the outside to the inside wall, making it effective against dampness. Additionally, the air trapped inside the cavity acts as a thermal insulator, keeping the building warmer in winter and cooler in summer compared to a solid wall. Statement 3 is incorrect because the typical cavity width is between 50 mm and 100 mm, not 10 mm to 20 mm.
Shortcut
To remember the rules for Cavity Walls, use the mnemonic "DIT" (Dampness, Insulation, Thickness): - Dampness: Primary purpose is to block moisture from reaching the inner face. - Insulation: Trapped air gap provides superior thermal insulation. - Thickness: Standard cavity width is 50 to 100 mm (not 10 to 20 mm).
Common mistake
A common mistake is selecting Option D by assuming that all three statements are correct and overlooking the specific numerical dimensions for the cavity width. Students often confuse the standard cavity width (typically 50 mm to 100 mm) with a much narrower gap of 10 mm to 20 mm. Another mistake is selecting Option B or C by misjudging the primary functional requirements of dampness prevention and thermal insulation in cavity wall construction.
Correct answer: A) 1 and 2 only