Fiberglass batts must be installed perfectly
to provide maximum R-value. The void or
empty space around the electrical outlet
box is a common mistake during installation.
Fiberglass batt insulation was invented by the Owens Corning Corporation back in 1938. For many years, it's been the dominant type of insulation used just about everywhere in a typical house - floors, walls, ceilings and attics. The keys to this popularity include low cost, a variety of thicknesses and widths to accommodate different application requirements, fairly easy installation, and widespread availability.
Today, the batt insulation category includes not just fiberglass, but also insulation batts made from recycled cotton and mineral wool. R-values for these different batt insulation are as follows:
|Fiberglass batts||R-3 to R-3.8 per in.|
|Mineral wool batts||R-4 to R-4.3 per in.|
|Cotton batts||R-3.7 per in|
Batt insulation can be unfaced or faced with a variety of materials, including kraft paper, foil-faced kraft paper and plastic. The faced side of the batt should always be oriented toward the conditioned space, rather that toward the exterior of the building.
Careful installation is critical
The main disadvantage with batts is that careful installation is required to eliminate energy-wasting airspaces or voids. It's very difficult to complete a fiberglass insulating job without leaving a few gaps in coverage, and even a small void can diminish overall R-value by 50%. Also, batt insulation loses R-value when it's compressed, overly "fluffed" or wet. And even when it's perfectly installed, batt insulation won't stop air leaks, so spaces must be air-sealed before batt insulation is installed.
Fortunately, existing batt insulation can often simply be left in place while new insulation is installed over or around it. Specially formulated Injection Foam insulation can be placed in wall cavities, flowing around existing batts and offering the dual benefits of air sealing and improved R-value. In the attic, loose-fill fiberglass or cellulose insulation can be blown over existing fiberglass batts after air-sealing the attic.
With a comprehensive insulation evaluation, Dr Energy Saver can help you identify if batt insulation is right for your home. Contact Dr. Energy Saver today for a free insulation consultation and estimate.
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