Why should the kraft paper or standard foil vapor diffusion-retarder facings on blanket insulation be covered?

The correct answer emphasizes the need to cover kraft paper or foil vapor diffusion-retarder facings primarily due to fire safety concerns. The kraft paper and standard foil used as facings on insulation material can pose a fire hazard if exposed. In the event of a fire, these materials can ignite and contribute to the spread of flames. Covering them with a non-combustible material helps mitigate this risk and enhances overall safety within the structure.

Handling insulation in this manner is crucial for ensuring fire-resistant construction practices. In many building codes, the requirement for covering such exposed materials is to promote safety by reducing potential ignition sources. While thermal efficiency and structural support are important factors in building design, they do not specifically address the immediate dangers posed by exposed vapor retarders in relation to fire hazards. Therefore, focusing on the necessity to cover these facings with non-combustible materials is vital for maintaining fire safety in residential and commercial structures.