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Insulation Overview

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

Facings as Vapor Barriers

The main function of facings is to act as a vapor barrier to minimize the rate and volume of water vapor flow. This helps prevent moisture from accumulating in the insulation blanket and the structure, ensuring consistent thermal values and lower heating and cooling costs.

The effectiveness of a vapor barrier depends on:

  • Location within the insulated section
  • Permeance
  • Proper installation

Facings intended to serve as vapor barriers should be installed on the inner, heated surface of the insulation, where vapor pressure is highest. This helps prevent vapor from reaching cooler air and condensing.

Vapor barriers prevent vapor from reaching cooler air and condensing.

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; any rating above 1.0 is not considered a vapor barrier.

Installation and Selection

Proper selection and installation of facings is imperative for maximum effectiveness. Please refer to our installation instructions for correct procedures. Facings that have been torn or punctured are no longer capable of blocking water vapor..Be sure to quickly patch any holes in the vapor barrier.

When selecting a facing, special consideration should be given to reflective quality. A facing with high reflectivity reduces the need for artificial light in work areas, which reduces energy costs and may increase productivity.

Facing Temperature Limits

While the fiberglass insulation itself is not affected by cold weather, the facing is. Cold temperatures can cause cold crack, which means the facing has become brittle and, if handled, can crack. Bay Insulation recommends that vinyl-faced fiberglass products only be installed in temperatures above 40 degrees.

Need more information? Please see the detailed specifications on the wide range of available facings below.

Popular Facings


Specialty Facings


Specialty Facings II