Condensation Control

The condensation process occurs when warmer moist air comes in contact with cold surfaces such as framing members, windows and other thermally conductive accessories, or the colder region within the insulation itself (if moisture has penetrated the vapor retarder). Warm air, having the ability to contain more moisture than cold air, loses that ability when it comes in contact with cooler surfaces or regions. When this happens, excessive moisture in the air is released in the form of condensation. If this moisture collects in the insulation, the insulating value is decreased.

In dealing with condensation, air may be considered to be a mixture of two gases-dry air and water vapor. One thousand cubic feet of air at 75°F can hold up to 1.4 pints of water. At 45°F, it can hold only 0.5 pints.

Relative Humidity is a percentage measurement of the amount of water vapor present in the air in relation to the amount it is capable of holding at that temperature. Therefore, 50% Relative Humidity would mean that the air is carrying only one-half of the total amount of moisture that it could be holding at that particular temperature. Cold outside air is usually much drier than warm inside air. Therefore, you can lower the Relative Humidity by bringing in outside air to mix with and dilute the moist inside air. At 100% Relative Humidity, the air is "saturated."

The temperature at which the air is saturated and can no longer hold additional moisture is called the dew point temperature. Whenever air temperature drops below its dew point, excess moisture will be released in the form of condensation. Condensation problems are most likely to occur in climates where temperatures frequently dip to 35°F or colder over an extended period of time.

Facings

In addition to acting as a decorative protection barrier, facings serve an integral part of the overall insulation system. Facings provide vapor barriers, light reflectivity and structural strength. In some cases, a reinforcement of fiberglass scrim is used for extra rigidity and greater impact resistance.

The effectiveness of a vapor barrier depends on three primary factors:

1) Location within the insulated section

2) Permeance

3) Proper installation

Surface Air Film Coefficient (F)

The amount of heat flow in BTU's per square foot per hour between an exposed surface of a material and the adjacent air. It is the measure of the conductance of heat through the air film that clings to all surfaces.

Pre Engineered Metal Buildings

Deciding to use a pre-engineered metal building is a wise choice. But, there is important information you will need to provide to the manufacturer in order to have your new steel building to be designed to precise specifications. Understanding your building needs and restrictions can help when you consult with a steel building manufacturer.

A few questions you need to ask yourself once you decide to buy a metal building system. What are my size limitations? What will the building be used for? What special building requirements are needed?

Why the answers to these questions are so critical is that they expose precisely what kind of pre-engineered building system will satisfy your needs. Metal church buildings have very different structural demands than those of mini storage buildings. If investing money into a pre engineered metal building system it only makes sense to research all options.

Perplexed about where to start? Contact a manufacturer; they will ask you the right questions to get what information they need to suitably determine your building needs. They can also help you review your requirements to equip your structure with the appropriate interior and exterior features.

Thermal Conductance (C-Value)

A measure of the amount of heat that passes through materials of any thickness.