Controlling Condensation Creates Healthier Buildings
Metal buildings can be difficult places to insulate and condition, and condensation in metal buildings is a big problem. The Icyene Foam Insulation System can solve these issues. Let's investigate further.
Understanding and Controlling Condensation
Too often, condensation prevention is not given adequate attention in the construction process. The following is an attempt to explain condensation in general and in metal buildings, what the consequences of condensation are, and how Icynene foam insulation can solve the problem that fiberglass has failed at.
What is Condensation
The air we breath is made of many gasses. One of these is water vapor, which is just water in a gaseous form. When air contacts an object at a temperature where water vapor changes to a liquid, it is known as the dewpoint temperature. This is Condensation. The amount of water air can hold depends on its temperature. The dew point temperature is the temperature at which air con no longer retain its water in a gaseous state. This temperature where liquid water begins to form is called the dewpoint temperature. The ration of water vapor in the air compared to the maximum amount of air it can hold at a given temperature is called "relative humidity". When air is absolutely dry its relative humidity is 0%. When air has reached the dewpoint, its relative humidity is 100%. The higher the relative humidity the greater the water content in the air at that temperature.
Air and water move from area of high pressure to low pressure. Each component in air is driven by the pressure of each component. If air is exposed to changing temperatures, the aire will be driven from the area with higher pressure to the area with lower pressuer. This is the natural phenomenon that moves water through the air or any other porous material.
Where does the moisture come from?
Moisture comes from many places and process. Gas source heaters give of a lot of moisture in the combustion process. These gasses are very hot and can hold large quantities of water. The temperature of air coming out of a propane space heater can be over 350 degrees farenheit. When this air combines whith the ambient air, it cools off and the amount of moisture that the air can hold will decrease until the air contacts anything colder than the dewpoint of that air. This is extremely common in metal buildings. The condensation will occur on purlins, pipes, metal roof and wall panels. We humans also give off a lot of water though breathing, and perspiration.
Even before a building is fully completed, there can be significant amounts of moisture introduced into the building. Excavated earth contains a significant amount of moisture. As the soil is exposed to the ambient air, the moisture will be given off. If the building is closed, this moisture will stay within the building. As soon as the temperature drops below the dewpoint of that air/water mixture, condensation will form. New concrete is another source of large amounts of moisture. If the building is closed and concrete is poured, a way must be provided for moisture to be vented to the atmosphere. Concret slabs can take years to cure. The first year is the worst, hundrends of gallons of water used to mix the concrete are evaporating and getting trapped inside the building. Ventilation should always be considered as a preventive measure during the construction schedule. Wood can also carry large quantities of water.
Effects of Condensation
Now that we know the process that creates condensation, we can look at the effects of condensation on building materials. For the metal building industry, the most common materials are corrugated steel and fiberglass insulation. Most metal is treated against corrosion and rust. Rust degrades the integrity of the metal in the building, resulting in deterioration and a shortened life expectancy. The surface treatments applied to metals help to prevent oxidation. However, during construction screws are driven though the treatments leaving them with vulnerabilities. The best practice would be to prevent the causes of rust, ELIMINATE CONDENSATION in metal buildings.
The insulating material most commonly used in metal buildings is the fiberglass blanket. Water in its liquid form is a good conductor of heat. The presence of water vapor or condensed water in fiberglass insulations will increase its thermal conductivity because of the higher conductivity of water. Fiberglass can not stop the condensation process because it is not an air barrier. So condensation is enevitable with fiberglass. Once fiber glass is wet it takes a long time to dry and it the added weight of the water will cause sagging of the batts creating an even larger airspace between the insulation and the substrate.
One way to control condensation is through the use of effective continuous vapor barriers. Vapor barriers are used to limit the migration of moisture onto the metal sheathing. In the metal building industry, this is typically accomplished through the use of different types of facings on the fiberglass insulation. Vapor barriers do not stop vapor transmission, but they serve to reduce its movements. Because moisture travels from areas of higher vapor pressures to lower vapor pressures, the vapor barrier should always be placed at the point of the highest vapor pressure. Fiberglass batts rarely if ever form an effective continuous vapor barrier. When installing the batts they must be mechanically fastened with staples, nails, or screws all of which disrupt the vapor barrier and render it useless. Once the moisture is introduced into the fiberglass blanket, moisture is trapped between the steel skin and the vapor barrier. As the temperature changes inside the blanket, the water will go through a cyclic life of water vapor and condensed water. This creates the potential for mold, mildew, and other fungi. The only way that the moisture can be removed is if the temperature conditions are held long enough for the water to escape the blanket, either through the vapor barrier or openings in the barriers.
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Note: The objective of this page is to help people looking to build metal buildings, and the metal building industry to better understand the effects of condensation in metal buildings. The information included is believed to be reliable. However, the ultimate responsibility to prevent and eliminate condensation falls to the design of the building. Please send questions to email@example.com
Icynene is sprayed in place to form an effective continuous air and vapor barrier. It expands in seconds to encapsulate the metal roof, purlins, and pipes. Since we are not allowing the moisure to reach the metal substrate we are eliminating the possibilty for condensation. Let Insulation For Life effectively insulate your metal building in the Dallas area with the Icynene spray in place foam insulation system.