Insulation: Fiberglass vs. Cellulose

Insulation: Fiberglass vs. Cellulose

Check the insulation in your ceilings, walls, attic, floors and crawl spaces to see if it meets recommended levels. Adding insulation in the attic is the easiest and most cost effective way to insulate your home. Remember, the higher the R-value, the better your home will resist losing heat. If your home has less than R-22, you should consider adding more insulation.

Proper ventilation provides moisture control and reduces summer cooling bills. Attic vents ensure proper airflow.
Do not block vents with insulation, and keep insulation at least three inches away from lighting fixtures or other heat-producing equipment unless it is marked "I.C."
If you do add insulation to your home, always follow the product instructions and wear proper protective gear.
Home insulation: What you need to know

Are you thinking about checking your home insulation but aren't sure where to start? It may be best to have a professional contractor do the job for you.

Nevertheless, you can start the process yourself, which will help when a contractor comes to look at your house. The process is important. The U.S. Department of Energy (DOE) estimates that you can reduce your heating and cooling needs by as much as 30 percent by investing just a few hundred dollars in proper insulation and weatherization products.

Here are some tips that will help you decide how good your insulation is in your house. First, understand that air infiltrates in and out of your home through every hole, nook and cranny. Here are the leading sources of home air leaks:

floors, walls, ceilings - 31 percent
ducts - 15 percent
fireplace - 14 percent
plumbing - 13 percent
doors - 11 percent
windows - 10 percent
fans and vents - 4 percent
electric outlets - 2 percent

You will need to check the insulation in your attic, ceilings, exterior and basement walls, floors, and crawl spaces to see if it meets the levels recommended for your area. Insulation is measured in R-values — the higher the R-value, the better your walls and roofs will resist the transfer of heat. Correct R-values are based on local climate conditions.

Insulation usually comes in four types — batts, rolls, loose-fill and rigid foam boards. Batts are made to fit between the studs in your walls or between the joists of your ceilings or floors. Rolls or blankets can be laid over the floor in the attic while loose-fill insulation is blown into the attic or walls with a special machine. Rigid foam boards are made to be used in confined spaces such as exterior walls, basements, foundation and stem walls, concrete slabs and cathedral ceilings.

The easiest and most cost-effective way to insulate your home is to add insulation in the attic. Do you have enough now? Measure the thickness of the insulation (if you have any!). If there is less than "R-19" (six inches of fiberglass or rock wool or five inches of cellulose), then you could probably benefit with more attic insulation.

The Zip Code Insulation Program will tell you the most economic insulation level for your new or existing house. This interactive program can be accessed at The Department of Energy and the Oak Ridge National Laboratory developed it. Check it out!

There is a great deal more to know about insulating your home. Hopefully, however, you now know enough to get started and will be able to discuss your needs with a professional contractor. Remember, too, that your local electric cooperative is always glad to help you implement energy conservation measures. Your co-op loves to help save you money!

Crawl Space InsulationCrawl space insulation will reduce the amount of heat your home loses through the floor. It can be a very effective energy-saving measure in cold climates. Crawl space insulation can be installed directly beneath your home's floors, or at the perimeter of the crawl space on the inside of the foundation walls.

Fiberglass batts are often used for insulating floors, with wire or wood strips used to hold the batts in place. Wide fiberglass blankets can also be used to insulate crawl space foundation walls, though they are prone to moisture damage in this application. The best choice for insulating interior foundation walls is foam insulation that is installed either in rigid sheets, or in a professionally applied spray application.

When installing foam insulation, some building jurisdictions may require protection by a fire barrier such as drywall that faces toward the crawl space. It's also a good idea to install a heavy plastic ground-moisture barrier that covers any bare ground in the crawl space. This will prevent moisture from rising out of the ground and damaging the home or saturating the insulation. Check with your local building authorities to confirm any such requirements.

Whether you insulate the floor or foundation wall, you should insulate the rim joist at the same time. The rim joist pockets, formed where the floor meets the foundation, are a large source of heat loss and air leaks. Again, fiberglass is most commonly used here, but moisture often migrates behind the fiberglass and condenses on the cold rim joist, causing damage from mold or rot. Sprayed foam insulation in the rim-joist area is now a common choice, and provides both insulation and air sealing at this critical building junction.

Attic Insulation

You can lose a lot of energy through your home's attic if you don't have sufficient insulation. If your existing attic insulation is less than 6 inches thick, or rated at less than R-20, it's probably a worthwhile project to add more. You should add insulation to total 12 to 20 inches, or at least R-35 to R-50.

Loose-fill fiberglass or cellulose insulation is the best materials for insulating attics. If you are handy and don't mind getting dirty, you can install the insulation yourself. You can rent small insulation-blowing machines from many lumber yards or rental companies, and you should be able to finish the job in a day. Professional installation is usually a good value, however, and ranges from 35¢ to 80¢ per square foot.

Before you insulate your attic, take some important preparatory steps:

Confirm that you don't have any roof leaks that can damage your home and reduce the effectiveness of your insulation. Fix these before you insulate.
Inspect the wiring in the attic. It should be modern plastic-sheathed electrical cable. If you have knob-and-tube wiring or older cable with a fabric sheath, rewire the attic before installing the insulation. Be sure that any electrical boxes have covers. You may need to call a licensed electrician for this work.
Seal any air leaks in the attic, since these can account for a large portion of your home's heat loss. Air leaks are often located around the chimney, plumbing vents, light fixtures, and wherever the ceiling has been dropped such as in kitchens and bathrooms.
Build a dam around your attic hatch so that insulation doesn't fall into the home when you open the hatch. An insulation dam can be made of plywood, cardboard, or foam insulation board. When you are working in the attic, step only on the wooden framing. Your home's drywall or plaster ceiling is not made to walk upon, and won't support your weight.
Insulating your home is one of the best ways to reduce your electric bill and improve your comfort. Fiberglass and blown cellulose are the most commonly used insulation fibers, but it's important to know which is the best option for your home.Fiberglass insulation is purchased as blankets or loose fill. Blankets usually come in rolls, and are installed in walls, floors, and attics. They often have a paper or foil face that helps slow moisture movement. If you install fiberglass blankets in your wall cavities, pay close attention when cutting them to size. Cut them carefully around electrical boxes and wires. A sloppy fit can negate much of the insulating value of fiberglass blankets.

Fiberglass loose fill is installed in attics and wall cavities. It is a good material in moist, humid climates since it absorbs very little water. It's also a good material for retrofitting the wall cavities in metal-skinned mobile homes. Its low density puts less pressure on the ceiling or underbelly, reducing the potential for damage to the structure. Fiberglass loose fill is usually installed by professional insulators. It's easy to over-fluff this material, reducing its density and encouraging heat-robbing air currents. Be sure your insulator installs it at the manufacturer's recommended density.

Cellulose insulation is purchased as a loose-fill material, and is always installed with an insulation blower. It's made from recycled paper that is treated with a flame retardant and rodent deterrent. It can be purchased at lumber yards and the blower can be rented so you can install it yourself. Densely packed cellulose creates a better air seal than fiberglass because its small fibers pack into corners, crevices, and small air leaks. Because of this, cellulose is frequently used in older homes. Cellulose is also slightly cheaper than fiberglass.

You shouldn't install cellulose insulation if you live in a very humid climate since it absorbs moisture easily. This will tend to wash out the fire retardant, decreasing its fire resistance and possibly corroding metal siding, wiring, or roofing.

If you have questions about which insulation is right for you, consult a professional insulator and enjoy a more comfortable home in all seasons.