The facing material of metal building insulation plays several important roles, and you should carefully consider your choice. Different facings vary in three key qualities: workability, permeability, and durability.
of a facing refers to the temperature conditions required for installation. Cold causes some vinyl facings to become brittle, and these may crack or split during installation or shipping
(which means we cannot sell it for delivery to colder areas in Winter). Not only does this kind of damage look bad, but it will seriously degrade the facing's ability to do its job as a vapor barrier. The comparison table at the bottom of the page lists the minimum temperature at which various materials can be safely installed.
(water vapor transmission rate) of a facing refers to the rate at which water vapor will pass through it. As described on the main insulation
page, metal buildings need a good vapor barrier. The effectiveness of various materials is measured in "perms," and lower numbers mean greater resistance to moisture. For example, a 1.0 perm barrier will transfer up to 50 gallons of water a week into a 50,000 sq. ft. building while a .09 perm material will transfer only about 5 gallons (materials with a perm rating above 1.0 are considered ineffective). Most facings are layered with different materials, and the better ones usually incorporate polypropylene or some other essentially waterproof material (see the comparison table below for more info).
(mullen bursting strength) of a facing indicates how well it stands up to physical stress without ripping or tearing, which is important because the facing is usually left exposed on the interior of a metal building. The least durable facings are made of one layer of unreinforced vinyl, which can be punctured or damaged by only light contact. Reinforced facings have a layer of "scrim" or mesh of fiberglass, nylon, or some combination of materials that help prevent the facing from tearing. When choosing facings, you should consider where and how the insulation will be used. For example, roof insulation will probably receive less stress than exposed wall insulation, which may be bumped or scratched frequently (see comparison table below).