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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.


The Disaster Advice Glossary and its contents are the protected copyright of Disaster Advice

Vacuum Sampling

The collection of surface matter through a vacuum. Vacuum collection devises can be special upright HEPA vacuums to small cassettes attached to a vacuum pump. After collection the vacuumed material is either field identified under a microscope or in a laboratory. See Air Sampling Adsorbent Sampling Bulk Material Sampling Soil Sampling Surface Sampling Swab Sampling Tape Lift Sampling Water Sampling Wipe Sampling



An independent confirmation method determining that the services provided by the contractor were completed as agreed.


Validation Sampling

A laboratory verification method substantiating that the water mould bacteria or chemical mitigation services provided by the contractor left no harmful effects behind. See Clearance Sampling


Valley Fever

Valley Fever is also known as San Joaquin valley fever desert fever or desert bumps. The disease is called Coccidioidomycosis caused by the fungi Coccidioides immitis and not to be confused with the fungus disease Cryptococcus neoformans associated with pigeon feces. Valley fever was first identified in the San Joaquin valley in Central California. Valley fever is caused by a soilborne fungi that has resulted in farm and construction workers dying from inhalation of the fungi into their lungs. The fungi over recent years has come south through what is called the lower Sonora region of California into Los Angeles. Health and Safety Note Valley fever is mentioned because during the recent southern California earthquake of 1994 much of the valley floor became exposed to the disturbance of airborne clouds including spores. California Contractor Note Emergency response and restoration contractors



The act of estimating or appraising. A process of valuing estimating or determining a value of a material or object. Valuation may take into account depreciation based on age or wear and tear.


Value Protection Clause

In insurance terminology a value protection clause in an insurance policy may be provided when there is an increase in the limit of insurance applying to a specific coverage which reflect changes in costs of construction and personal property values. Any such increase will typically be made on the renewal date of the policy or on the anniversary date of 3-year policies paid annually.



Vapour in the strict sense is a gas. Moisture vapour is simply moisture in a gaseous form. Vapour has weight and mass which is measurable.


Vapour Barrier

One of several acceptable material membranes used to prevent moisture and moisture vapour in transferring or penetrating through a vapour barrier. The membrane may be a 15 to 60mm thick plastic placed under the concrete slab or an asphalt treated material.


Vapour Emissions from Concrete

Moisture vapour emission is a quantity of vapour or equivalent liquid water emanating from a concrete slab over a period of time. Although vapor emission is influenced to some degree by temperature and humidity differentials the most important influence is the quality of the concrete as measured by permeability and porosity. The effect of vapour pressure on vapor emission is negligible.


Vapour Pressure and Vapour Emissions

Moisture vapour pressure from concrete is the direct relationship between the moisture content in concrete and pressures forced on to the concrete. Vapour emissions is the result of escaping vapour from a material into air. Vapour pressure and vapour emission are related only to the extent that we are talking about the same vapor and the fact that each may be influenced by some of the same variables. Vapour emissions of water in the atmosphere is governed by and is directly related to temperature and humidity.


Vapour Pressure as Back Pressure In Concrete

A misnomer and common conception that concrete appears to represent itself as having or producing a vapor back-pressure. Education Note Vapour pressure rises and falls according to the two variables of temperature and humidity. Vapour pressure is %u0022not%u0022 capable of accumulating or producing a %u0022build-up of trapped vapor pressure%u0022 The term %u0022back pressure%u0022 as it relates to vapor pressure in concrete probably came about in an attempt to explain the higher volume of moisture accumulation that may occur in the uppermost layer of concrete after covering it with a low-permeable or non-permeable flooring material or sealer. Moisture that collects in this fashion is usually due to improper concrete curing which has resulted in a surface with demonstrable higher permeability and porosity than the interior section of the concrete. The higher permeability and porosity of the surface allows a %u0022reservoir effect%u0022 to occur which will temporarily result in higher than normal vapour emission measurement after the floor covering is removed. The vapour pressure readings will return to %u0022normal%u0022 when the stored moisture is allowed to be expelled.


Vapour Pressure Charts

The in an atmosphere vapour pressure charts are of temperature and humidity that calculate vapour pressure of moisture in pounds per square inch PSI.


Vapour Pressure in Floors

Vapour pressure is roughly defined as the pressure caused by the energy of moving molecules of the vapour measured as vapour pressure.


Vapour Pressure in Floors over Concrete

The amount of moisture as vapor pressure that emits through force from a substrate. Education Note As it relates to floors over a concrete substrate the vapor originates from moisture within the concrete itself. Vapour pressure of water in the atmosphere is governed by and is directly related to temperature and humidity. Vapour pressure from the floor is offset sometimes overcome by vapour pressure within the space above the floor with a net pressure differential. Vapour pressure in a floor or concrete is a force per unit are independent of atmospheric surroundings of a room except for temperature and relative humidity.


Vapour Pressure Osmosis

The diffusion or spreading of water through a membrane until they are mixed. Osmotic pressure is the pressure produced by the tendency of a relatively pure fluid to pass through a semipermeable membrane into a relatively impure solution. Education Note In the case of floors the %u0022fluid%u0022 is water the %u0022semipermeable membrane%u0022 is concrete and the %u0022relatively impure solution%u0022 is moisture plus dissolved salts in the concrete. Although osmotic conditions are capable of creating problems that will become quickly apparent usually within a couple of weeks there is no evidence to support osmotic pressure as a primary cause of a floor failure. Water condensing under a flooring material from vapor emission is %u0022pure%u0022 and creates osmotic pressure as it is inclined to move toward %u0022impure%u0022 moisture in the concrete containing dissolved salts. The most extreme pressure to be expected in concrete is probably on the order of 8 to 10 p.s.i. The pressure created by osmotic pressure is relatively low and it will not normally disturb cured adhesives or damage concrete. See Moisture Related Flooring Failures


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%u0022 to 2%u0022 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


Vapourization of Fire Department Water

During a building fire event the fire department uses large amounts of water from fire hoses to reduce and eliminate the flame and the flammable source. Contractor Note The heat from a fire in an enclosed atmosphere will allow a stream or spray fog of water to expand up to 1700 times its mass from the waters original dispersion size. This results in liquid water to turn into steam water droplets then the droplets are changed into a moisture vapour state. With extremely hot-heat water from a fire hose immediately goes to the vapour state. With heat vapourized water and cooler building material surfaces the building materials absorb the water vapour rapidly and often the water vapour is actually forced into porous cells of the building matrix through advection and conduction. Dehumidification of a wet building from a hot-fire is complicated by the radical dispersion of vapourized moisture molecules in building materials along with the atmospheric stresses brought about from heated forces of increased air volume. See Absorption Advection


Veneer Covering

A thin sheet of wood or composite material that was made to look like wood which is laminated on to the surface of a desk cabinet counter shelf for example. Education Note Veneer coverings can be sensitive to moisture and temperature and they may delaminate from the surface to which they are attached.



An opening which air is allowed to pass through freely. Vents are part of a buildings natural air intake and exhaust system. Vents are common to basements crawlspaces plumbing attic and roof.


Ventilation for Acceptable Indoor Air Quality

Ventilation for Acceptable Indoor Air Quality are the design engineering installation and maintenance of a heating ventilation and air-conditioning system as found in ASHRAE Standard 62-1989. The Ventilation for Acceptable Indoor Air Quality design requirements recommend 15 cubic feet of air per minute CFM per person of fresh outdoor air into buildings.


Ventilation Systems

The engineered designed and mechanical system of a building. Ventilation systems bring in fresh filtered air and they take out exhaust used air. Energy efficient buildings have return air systems that allow filtered building air before it is sent back to the occupied building air space.



One of several methods acceptable to exhaust and get rid of gases vapors and airborne pollutants from a work space. One of the easiest methods is the use of exhaust fans pointed downwind from the outside air stream. A mechanical system of a building which allows the building to bring in fresh air and exhaust contaminated air.


Venturi Air Scrubber

An air pollution control device that removes particulates vapours acid mists and gases from polluted air streams. The venturi effect is created at the throat of the narrow section of the duct called the venturi throat. The velocity of low air pressure increases in the duct as pressure builds towards the venturi throat and picks more up velocity as it passes the specially designed throat resulting in higher collection efficiency of pollutants.


Venturi Effect

The increase of air velocity of a stream of air through a constriction or duct.


Vertical Window Framing

The plumb straight and true framing of the rough window area that allows a window assembly to be installed properly.


VHS Vertical and Horizontal Spread

The VHS model considers a worst-case scenario and makes assumptions about the potential of further lateral and horizontal damage due to a contamination. The VHS model for water and sewage damages in a contaminated building for example results in a technician to consider potential unknown or hidden damage as part of the damage assessment and survey. The VHS model can be adopted to other damaged environments such as a fire damaged building or high-rise where smoke soot and water may have migrated. VHS in this case has been adopted from EPAs VHS model for hazardous environments.



Viable means alive. The alive cells and spores of bacteria and protozoa fungi and yeasts that are alive and sometimes dormant which can be grown and reproduced in a laboratory. See Culturable Non-Culturable Non-Viable


Viable Fungi Colours

When fungi and molds are alive they are multi-colored from red pink to orange. Some common examples are Black Color Fungi - Alternaria Chaetomium Ulocladium and Stachybotrys. Stachybotrys produces a very deep black to dark purple color. Green Color Fungi - Aspergillus and Penicillium species. When these species sporulate they turn a velvety green. The mycelia growth itself is typically white. White Color Fungi - Fusarium yeasts and mycelia growth indicating the start of mould growth or young non-sporulating growth such as identified on Acremonium Aspergillus and Penicillium during their youth growth cycle and before maturity.


Video Documentation

The real-time documentation and 3-dimensional view of the environment or situation involving a claim or event. See Inventory


Video Inspection

An electronic photographic representation or documentation of a claim or damage to a property through the use of video cameras. Video documentation allows for a 3-D presentation to be completed with voice to explain the content of the video.


Vinyl Flooring

A resilient flooring system that is made in sheets or tiles. Vinyl flooring is composed of vinyl plastics binders mineral fillers color patterns and a scratch resistant coating.


Visible Fungi Contamination

Visible fungi means that fungi which is observed on surfaces by the eye. For visible fungi to become noticeable to the average person millions of spores must be present in a collection. A surface area the size of a quarter can support tens to a hundred million fungal spores depending on spore type and size.



Empty spaces in a building that are designed for no particular purpose such as an enclosed walled off area under the steps leading to another floor. See Pockets of Saturation



In water damaged buildings volatile describes water which evaporates or vapourizes in the air rapidly and at high temperatures.


Volatile Organic Compounds VOCs

A category of organic compounds with a relatively high vapour pressure which a majority are air contaminates. VOCs are carbon-hydrogen bonded compounds hydrocarbons but they also may be aldehydes chlorinated hydrocarbons ketones and other hydrocarbon-based compounds. VOCs are in paint carpet adhesives binders household cleaners film and materials that make up most of today manufactured furniture. Excessive VOC exposure to some sensitized individuals produces an immediate health response and reaction to the VOC resulting in skin irritation nausea depression reactions to the central nervous system and/or an increased risk of cancer.



The tendency or ability of a liquid to vapourize. Such liquids as gasoline and alcohol because of their well-known tendency to evaporate quickly are called volatile liquids.


Volume of Air

The amount of air in a given air space. See Air



FEMAs coastal flood designation for portions of the 100-year floodplain subject to a storm-driven velocity of waves of three feet or more in height.


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