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A vapor barrier on the warm side of the envelope must be combined with a venting path on the cold side of the insulation. This is because no vapor barrier is perfect, and because water may get into the structure, typically from rain. In general, the better the vapor barrier and the drier the conditions, the less venting is required. [7]
Open-cell foam is porous, allowing water vapor and liquid water to penetrate the insulation. Closed-cell foam is non-porous, and not moisture-penetrable, thereby effectively forming a semi-permeable vapor barrier. (N.B., vapor barriers are usually required by the Building Codes, regardless of the type of insulation used.
In order to achieve these objectives, all building enclosure systems must include a solid structure, a drainage plane, an air barrier, a thermal barrier, and may include a vapor barrier. Moisture control (e.g. damp proofing) is essential in all climates, but cold climates and hot-humid climates are especially demanding. [8]
Concrete normally allows moisture to pass through so a vertical vapor barrier is needed. Barriers may be a coating or membrane applied to the exterior of the concrete. The coating may be asphalt, asphalt emulsion, a thinned asphalt called cutback asphalt, or an elastomer. [9] Membranes are rubberized asphalt or EPDM rubber. Rubberized products ...
Housewrap functions as a weather-resistant barrier, preventing rain or other forms of moisture from getting into the wall assembly while allowing water vapor to pass to the exterior. If moisture from either direction is allowed to build up within stud or cavity walls, mold and rot can set in and fiberglass or cellulose insulation will lose its ...
Waterproofing with two component system. In buildings using earth sheltering, too much humidity can be a potential problem, so waterproofing is critical. Water seepage can lead to mold growth, causing significant damage and air quality issues. Properly waterproofing foundation walls is required to prevent deterioration and seepage.
Processing equipment is used to regulate pressures and heat in a uniform and consistent manner. There are two main processing methods which correspond to the materials used for the SIP core. When manufacturing a panel with a polystyrene core both pressure and heat are required to ensure the bonding glue has penetrated and set completely.
In March, 2008, the city of Portland, Oregon, granted a waiver of the requirement for a vapor barrier or retarder when using cellulose insulation. [11] This appeal cited industry guidance that the combination of an exterior vapor retarder (as required by code) and an interior one could trap moisture in the wall, leading to damage.