| Home Energy Savings -- Installing Fiberglass Insulation |
From "Home Energy Savings" episode HES-103 |
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In this segment, the techniques are shown for installing fiberglass insulation in an attic. This is a fairly straightforward job for the do-it-yourselfer. The basic tools and safety equipment needed for the job are shown in figure A. Materials: Boards to navigate attic space Fiberglass insulation Tape measure Utility knife 4' straightedge Stapler Putty knife Rubber gloves Protective clothing and safety gear: Loose-fitting, long-sleeved shirt Long pants Hat or cap OSHA-approved safety goggles Disposable mask, rated for fiberglass Duct tape Safety Alert: When installing fiberglass insulation, there are safety precautions that should be observed. Fiberglass can release tiny fibers, which can be harmful if breathed into the lungs and which may irritate the skin. For work gloves, use standard rubber gloves since the fibers won't stick to the rubber and can be washed away easily. Wear a loose-fitting long-sleeved shirt, and use duct tape to seal the gap between glove and sleeve (figure B). Wear long pants, and wear a hat or cap. Kneepads are a good idea, as well, since you may be kneeling on the attic flooring or rafters. Use OSHA-approved safety goggles (figure C) -- not just glasses -- in order to completely protect the eyes from fiberglass dust. Wear a disposable particle mask (figure D) that's rated for fiberglass. An ordinary dust mask does not offer sufficient protection. Safety Alert: In an unfinished attic, place boards or plywood sheets across the joists so that you can safely walk in the attic. In our demonstration John Koplos, insulation specialist with Owens Corning, recommended adding R-25 insulation to the R-19 insulation in place in the attic -- resulting in a final R-rating of R-44. Laying new insulation over existing insulation is acceptable -- as long as an unfaced, no-vapor-barrier insulation is used. (In our demonstration, the blanket insulation used had a plastic wrap, making it easier to install. The wrap had perforations to ensure that it would not act as a vapor barrier, however.) Installing vapor-barrier insulation over existing insulation is one of the most common mistakes made by do-it-yourselfers when insulating attics. Another common mistake is using an insulation that is not suitable for the cavity in which it is being installed. If insulation that's too thick is compressed into a smaller cavity, the R-value of the insulation will be diminished.
Steps: - Lay down boards or plywood sheeting to help you be able to walk safely in the attic space.
- Determine the area of the space to be covered by measuring the width and length of the surfaces to be insulated (figure E). Multiplying those two numbers will result in the total square footage of the area you'll be insulating. Compare this measurement to the recommended amount needed in your attic. The necessary R-value for your attic will depend upon the manufacturer and style of insulation you choose. Check with the manufacturer's instructions on the packaging to determine how much insulation you'll need to achieve the desired R-value. In our demonstration, the width of the attic was 35', and the length was 20', yielding an area of 700 square feet.
- Once you've determined the amount and type of insulation needed, and the insulation has been purchased, begin staging the rolls in the attic. Place rolls around the perimeter of the attic for easier access during the installation.
- When laying insulation, it's a common mistake to cover up the soffit vents. Soffits are part of your overall ventilation scheme, and covering them blocks essential air flow in the attic. To prevent that from happening, use soffit baffles. Soffit baffles are stapled right to the bottom side of the roof planking (figure F), between the rafters and above the soffit vents.
- Begin laying in the insulation, starting at an area furthest from the attic access (figure G).
- In our demonstration, the new insulation was rolled out over the existing insulation, perpendicular to the joists (figure H).
- As you roll out the insulation, cut it to length using a utility knife.
- Tip: When you reach the end of a line, pull the insulation back slightly, then place it on a joist so that you have a solid surface to cut on. Using a straightedge as a guide, make your cut (figure I).
- After making your first cut, use the remaining portion of the roll and work back in the other direction. When you reach the end of that roll, butt a new roll up to the cut piece and finish the run.
- When you reach the perimeter, cut the end of the roll to fit. Using this technique results in the best use of the insulation and reduces wasted material.
- Tip: Lay the rows snugly together to prevent undesirable gaps or spacing.
- When you run into an obstacle like a cross-brace or pipe, cut a notch in the insulation roll to fit around the obstacle (figure J), then continue with the run.
- Areas around the perimeter of some attics can be rather tight and confining ( figure K). Just keep rolling out the insulation, but don't compress or squeeze it into tight spots, as this can decrease the insulation value.
- Safety Alert: If your home has recessed lighting in the ceilings, keep insulation at least 3" from the lighting fixtures (figure L) unless the fixtures are IC-rated (insulation-contact rated). Contact with a nonrated fixture could cause the fixture to overheat, causing a fire in surrounding materials. Fiberglass insulation is noncombustible, but surrounding materials such as wood, drywall or paint could catch fire.
Some new forms of fiberglass insulation (such as the type that was installed in our demonstration) is made using an "anti-itch" formulation, making it less likely to irritate the skin than regular fiberglass insulation.
In the segment that follows, blown-in cellulose insulation -- an eco-friendly alternative to fiberglass -- is installed in an attic.
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Owens Corning fiberglass insulation
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