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Disaster Advice Glossary
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Disaster recovery and restoration can be veiled in mystery to the many who have not undertaken specific training. This glossary explains technical terms to assist both report writing and the understanding of those technical terms so often misunderstood.
Definition
| Aerate: |
To expose to air and flush out. An example would be a humidified building that needs aeration of the indoor air with dryer dehumidified air; or a building that sustained a smoke-soot damage that will benefit through aerati |
| Aeration: |
In water damage restorative drying the process by which dryer air is artificially introduced into wet building materials and contents, allowing some building materials and contents to dry faster. See Air Movement, Air Dynamics, Acceleration Velocity, Advection, Turbidity |
| Air Movement |
Restorative Drying Note: In wet building drying the ability to move (force) large amounts of dryer air across wet surfaces, allowing liquid water to become moisture vapour, which is then exhausted or dehumidified. See Advection, Aeration, Airmover, Dynamic Pressure, Turbidity, Air Currents. |
| Boundary Layer: |
Associated with water damaged buildings, the boundary layer is the very thin layer of water immediately next to a solid body that flows more slowly than the rest of the fluid. Restorative Drying Note: The boundary layer is that layer of a wet porous floor where water continues to have surface tension. The boundary layer will inhibit evaporation from the surface of the porous material unless it is completely adsorbed by the hard surface, removed through suctioning, wicked-off through aeration or when complete evaporation takes place. |
| Crawl Space: |
a) The lower space of a raised foundation - between the ground and the first floor of a building. In a crawl space building code requires a minimum 18" aeration access from the ground and the floor joists. b) Any unfinished interior access and limited space between floors, containing ventilation, ducting, pipes, cables, or wiring of the building. C) A lower elevation of a building that has not been excavated deep enough for a basement. |
| Odour Counteractant: |
A process by which odor is reduced or eliminated. Some odours can be reduced through aeration or oxidation. Other odours require the cleaning and removal (sanitizing/deodorization) for the odour counteractant to be effective. Chemical odour counteractants (COCs) are meant to penetrate, dissolve and absorb the odor molecule, resulting in the neutralization of the odour. |
| Sheer Wall or Sheer Panel: |
A secondary support wall material attached to building framing, usually made of 4' x 8' sheets of plywood that complies with local building codes. Construction Note: Shear wall materials are designed and engineered to reduce the shear-stress on a building due in part to load factors, usually from the second and third floor weight loads effecting a wood frame building. In California, shear walls are being added in new construction for increased stress due to earthquakes. Mitigation Note: In water damage mitigation, sheer walls increase the need for additional problem investigation and problem solving when shear walls are present. Shear walls trap in the standing water and moisture vapor, not allowing the excess increased vapor pressure to escape within a reasonable period of time before fungi starts to grow. Wet shear walls cavities will not easily divulge that the interior wall cavities are wet and damp, since the face of the drywall may actually indicate is dry. Wet shear wall, wall cavities will not dry out on their own before mold starts to grow. After removal of the base coving, drill weep holes and aeration holes in drywall and through the shear wall, into the wall cavity. Force in dehumidified air into the wall cavity and monitor the wall cavity drydown. |
| Soil Aeration: |
Soil Air means the below-ground air that is trapped or available in the spaces between soil particles. Engineering Note: Decomposition of organic matter in the soil can cause high concentrations of carbon dioxide in soil air. Carbon dioxide combines with water vapor to form carbonic acid, thereby increasing the acidity of the ground. Soil air is often a result of anaerobic and aerobic conditions in the soil, and can vary depending on weather, atmospheric conditions, ground pressure, soil type, water/moisture and other influences. See Soil-Gas. |
| Soil Mitigation: |
The process by which contaminated soil is either removed or treated. In a black water sewage flood damaged substructure of a building where the sewage has come in contact with the soil or ground, soil remediation is the removal of sewage solids, effluents and waste water from the contaminated soil under buildings, then either treating the soil through aeration and detergents followed by capillary drying and/or the removal of the top layer of sewage saturated soil. |
| Vapour Transfer: |
The ability of a vapor, such as water vapor, to transfer from one surface or atmosphere to another. Education Note: Water vapour is a gas, and it can diffuse and pass through porous building materials easily. Water vapour can also pass through a solid building material, depending upon the difference in vapour pressure between the two sides of the solid material and the permeability of the material. Water vapour moves through solid materials at a rate proportionate to the difference in vapour pressure on either side of the material. The greater the vapour pressure on one side of a material, the faster the other side will be affected. Mitigation Note: In water damage mitigation, especially when it comes to wet wall drying, reducing the vapour pressure between wet walls or a wall cavity, greatly influences the vapour pressure and its permeability factor. For example, after drilling weep holes and aeration holes (usually 3/8" to 2") in size, drilled below the base board but above the mud sill or sill plate, allowing for forced dehumidified air to enter and pressurize the wall cavity. The increased dry air vapour pressure will increase the vapour transfer rate which the wet wall material will become dry faster. See Permeability Factor, Shear Walls. |
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