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He consults regularly on building code and industry standards. [1] Widely known for his "Perfect Wall" concept, Lstiburek identified four key control layers within the building envelope (bulk water, air, thermal and vapor) critical to a building's behavior, long-term performance, and viability. He is a proponent of understanding the concepts ...
The dampness results in vaporization where water vapor is transmitted into the building's interiors. Water vapor may enter the building through supply air ducts in building slabs and circulated by warm forced air. Water vapor can also enter a building through leaky return air ducts in homes with crawlspaces. [4]: 185–187
using an diffusion tight vapor barrier (vapor check) on the warm side of the insulation, i.e., inside the assembly on a heated building and outside on a cooled building. [4] Vapor barriers can be problematic because they difficult to install perfectly and also reduce the ability of a cavity to dry out when it does get wet.
In construction, a building or structure is waterproofed with the use of membranes and coatings to protect contents and structural integrity. The waterproofing of the building envelope in construction specifications is listed under 07 - Thermal and Moisture Protection within MasterFormat 2004, by the Construction Specifications Institute, and includes roofing and waterproofing materials.
Waterproof is defined by the ASTM as a treatment that resists the passage of water under pressure. [1] Generally, damp proofing keeps exterior moisture from entering a building; vapor barriers, a separate category, keep interior moisture from getting into walls.
Water vapor can also be indirect evidence supporting the presence of extraterrestrial liquid water in the case of some planetary mass objects. Water vapor, which reacts to temperature changes, is referred to as a 'feedback', because it amplifies the effect of forces that initially cause the warming. Therefore, it is a greenhouse gas. [2]
Ventilation in a structure is also needed for removing water vapor produced by respiration, burning, and cooking, and for removing odors. If water vapor is permitted to accumulate, it may damage the structure, insulation, or finishes. [citation needed] When operating, an air conditioner usually removes excess moisture from the air.
A vapor barrier is not typically intended to retard the migration of air. This is the function of air barriers. [8] Air is mixed with water vapor. When air moves from location to location due to an air pressure difference, the vapor moves with it. This is a type of migration of water vapor.