Calculated Thermal Values

Basically it is the reciprocal of the calculated U-Value. By definition it is the summation of all the R-Values for each of the building's components. This method of calculation does not consider the thermal short circuit effect of structural members, fastener population or the compression of the insulation at its structural members. It should also be noted that this type of calculation often indicates heat loss values for building envelopes that are lower than those actually found in the finished structure.

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.

Steel Storage Buildings

Some people might not fully appreciate their need for a steel storage building. Think about all the prized possessions, and family heirlooms you are storing in the garage or attic - or even worse - paying high storage fees. There is a far more economical way to store all of your possessions.

Whether you are looking to build a storage building for commercial or business use or a simple steel storage building for personal use - you cannot make a wiser choice than with a steel building system. The sturdy metal frame system makes steel storage buildings structurally superior. Pre-engineered steel buildings offer reliable protection to your investments.

As with all products, not every manufacturer utilizes high quality materials. Look for a company that explains its materials and its use. Be sure to ask questions about steel storage buildings before you buy, any manufacturer will be happy to address any concerns.

Recommended Installation Methods of Insulation

Roof insulation rolls are cut to lengths that will cover the distance from eave to eave, leaving a one-foot overhang on each side of the building.

1) Start at the end of the building and temporarily secure one end of the roll by attaching the insulation to the eave strut with double-faced tape.

2) Pull the insulation across the purlins with the vapor barrier toward the building interior. Double-faced tape attached to the opposite end of the insulation will keep tension on the roof roll while the metal panels are being attached over the insulation.

3) Install the next roll in the same manner, making sure the rolls are stretched tight, aligned properly and closely butted.

4) Fasten tabs using one of the methods described on the following page. Any rips or tears must be covered with matching facing tape to ensure a tight vapor seal.

5) Trim excess insulation flush to prevent it from acting as a wick and moving water into the building.

Perm Rating

The perm rating, or permeance, is a measure of the amount of water that passes through one square foot of material per hour. The lower the perm rating, the more effective the barrier. A facing material with a perm rating of 0.1 or less is considered excellent. Anything with a rating above 1.0 is not considered a vapor barrier.