What is the process called that prevents the passage of water vapor through walls under slight pressure?

The process that prevents the passage of water vapor through walls under slight pressure is known as damp-proofing. This technique is specifically designed to resist moisture and protect building materials from the damaging effects of water vapor that can penetrate through foundation walls and other structures. Damp-proofing involves applying a barrier, such as a liquid sealant or a membrane, to surfaces that may be exposed to damp conditions.

This process is particularly relevant in areas where groundwater may apply pressure to walls, potentially allowing moisture to seep through. By effectively creating a barrier against moisture vapor, damp-proofing helps maintain the integrity of structures and enhances the overall durability of the building.

In contrast, waterproofing refers to more robust protection against water intrusion, often used in locations with high water exposure. Sealing is a more generalized term that can refer to various materials or methods used to close gaps or resist flow, and insulating primarily focuses on thermal resistance rather than moisture control. Understanding these distinctions helps clarify why damp-proofing is the precise term for managing water vapor passage in this context.