Insulating Against Radiant Heat

Traditional forms of mass insulation, like fiberglass, are effective in preventing heat transfer by conduction and convection, but they less effect on radiant heat. Between 80 and 90% of the radiant heat striking fiberglass will pass through or be "emitted". Radiant transfer typically has as much impact on the temperature in a building as conduction and convection. For more information on radiant barrier facings click here.

Installation and Selection of Insulation

We provide the highest quality products available. However, proper installation and selection is imperative for maximum effectiveness. Please refer to installation instructions to ensure correct procedures are used. Facings that have been torn or punctured are no longer capable of blocking water vapor and may eventually do more harm than good. Be sure to quickly patch any holes in the vapor barrier.

When selecting a facing, special consideration should be given to its reflective quality. A facing with high reflectivity reduces the need for high light levels in work areas. This results in reduced energy costs and increased productivity.

Although the fiberglass insulation itself is not affected by cold weather, the facing is. Colder temperatures can cause cold crack, a situation where the facing becomes brittle and if handled can crack. Bay Insulation recommends that vinyl faced fiberglass products never be installed in temperatures below 40 degrees.

Controlling Condensation

Two things must be present for condensation to occur: warm moist air and cool surface temperatures below the dew point. The proper control of these two factors can minimize condensation.

In metal buildings, we are concerned with two different areas or locations: visible condensation which occurs on exposed surfaces below dew point temperatures, and concealed condensation which occurs when moisture has passed through the vapor retarder and into interior roof and/or wall cavities and then condenses on a surface below dew point temperature.

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.

Overall Heat Transmission Coefficient (U-Value)

A unit used to express heat passage through a complete building section, including air films. U-Values serve as a basis for determining transmitted heat loss. The lower the U-Value, the higher the insulation value.