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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]
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.
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.
It is important to realise a single R-value or U-value does not take into account the quality of construction or local environmental factors for each building. Construction quality issues can include inadequate vapor barriers and problems with draft-proofing. In addition, the properties and density of the insulation material itself are critical.
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 ...
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.
A structural insulated panel, or structural insulating panel, (SIP), is a form of sandwich panel used as a building material in the construction industry. SIP is a sandwich structured composite, consisting of an insulating layer of rigid core sandwiched between two layers of structural board.
Fire walls usually extend the full length of a building, from foundation to roof. [3] Fire barriers and fire partitions: They are similar to fire walls in operation; however, their height is limited to a single floor, from the slab of one floor to the underside of the next. [4] Coatings, e.g. to fireproof wood. [5] [6]