Insulation 101

Heating costs are going through the roof—literally. Heating and cooling costs account for between 50% and 70% of all energy costs in the average home. Given these unnerving statistics, it only makes sense to try to maximize the value of the energy you use. That means properly insulating your home.

Then and Now

Insulation wasn't always a popular idea. It’s not uncommon to see a postwar home with little or no insulation at all. But of course, that was in the days before you had to take out a home equity loan in order to pay your monthly gas bill. These days, experts recommend using a lot more insulation than in years past. By upgrading your insulation, you can realize significant savings, and now you might even qualify for government assistance to help pay for it. There are some relatively new tax credits that can save you money; check with your local government or a qualified tax accountant to see if you qualify.

The Advantages of Insulation

Everyone knows that adding insulation to your home can cut your home heating bills, but there are other benefits as well. When a home is well insulated, the temperature doesn’t fluctuate as rapidly as in a poorly insulated one, and it’s easier to maintain a comfortable temperature. What’s more, increased temperature stability means reduced wear and tear on your HVAC system, which helps prolong its life, and lowers operating costs to boot. And don’t forget that better insulation keeps homes cooler in summer as well as warmer in winter.

Good, Better, Best

Insulation is rated by something called an R-value, which indicates the degree of resistance a material has to heat flow. The higher the R-value, the greater the resistance that material has. The US department of energy (DOE) recommends an R-value of R-49 for the attics of homes in most states. If you live in the very southernmost regions of Florida, Texas, or California, you can get by with a mere R-38. Most regional building codes for new construction call for R-19 in walls and floors, but the more the merrier, of course. Typical 5-in. spacings between exterior walls and interior drywall allow for up to R-30 in most cases.

Types of Insulation

The 3 main types of insulation are blankets, blown-in, and rigid insulation. Here’s a handy thumbnail sketch of all of them.

  • Blown-In

This is the easiest to install, and the best overall choice for upgrading the insulation in existing homes. Basically, one of a variety of materials—such as cellulose, rock wool, polyurethane foam, or fiberglass—is fed into a mechanical blower, and the material is blown into cavities and voids in attic spaces. It is not necessary to remove flooring or plaster, and can be done in just a matter of hours. Cellulose, made of recycled newspaper that has been treated with a flame retardant, is perhaps the most popular of these choices.

  • Blanket Insulation

This type is primarily used in new construction, where it can be inserted into walls, floors and ceilings before these areas are covered with finish materials. The material comes in batts, or rolls, made of either rock wool or fiberglass. This type is also a popular choice for insulating attics, as it can be easily installed between the studs by non-professionals.

  • Rigid Insulation:

Rigid insulation is made of panels of either expanded polystyrene foam (EPS) or extruded polystyrene foam (XPS), which are cut to size and then glued in place.  EPS is the beady white stuff that is also used in some packing materials. XPS is tougher, and is typically pink or blue. At approximately R-5 per inch, they both have roughly the same insulating value, but XPS foam is pricier due to its greater strength. This form of insulation is commonly used on basement interior walls or exterior sheathing, including exterior foundations. This is a very high-quality form of insulation because of its ability to create an unbroken layer of insulation.

Some commercial construction uses structurally integrated paneling (SIPS), with built-in XPS. This material is stronger, with better insulating properties than stick-built construction with add-on insulation, again because of the lack of air gaps. Though change percolates slowly through the residential construction industry, SIPS are gradually becoming available for residential use, not just commercial use.

The drawback to this type of insulation—and it’s a big one—is that it is flammable, and can cause a fire hazard if it is not encased in drywall or another fire-resistant covering. If EPS or XPS insulation catches fire, it can add to the fire and create noxious smoke.

Places to Insulate

Here’s a list of the primary places to add insulation in your home.

  • Attics

Heat rises, so insulating your attic is a no-brainer. Make sure you install at least the federally recommended minimum amount of insulation for your part of the country, which is likely to be at least R-49.

  • Crawlspaces

If you’ve ever padded barefoot across a chilly tile floor, you might consider insulating your crawlspace. Laying some batts between the joists can make your home more comfortable, and cut down on your energy bills.

  • Garages

Garages are great candidates for insulation, as they frequently have exposed studs, and filling the walls in with blanket insulation is a snap. If you spend any time working noisily in your garage, your family reaps the added side benefit of better soundproofing, as well.

  • Non-Insulated, Above-Ground Basement Walls

If the floor of your dwelling isn’t well-insulated and well-sealed (e.g., along the baseboards), a huge amount of energy can be lost—often only because the basement walls were left rough and unfinished.

  • Exterior Walls

Adding insulation to exterior walls is trickier than most other areas, as they are usually already finished. And, few interior walls are good candidates for blown-in insulation as they must be completely hollow for that method to work well. Still, if you have a wall that is always icy cold to the touch in winter, it might well be worth taking it down to the studs. After removing the drywall, be sure to patch any rips, holes, or gouges in the vapor barrier, then add a thick layer of insulation, and hang a fresh layer of drywall over it to save on energy and make your home a more comfortable place to be.

Fight the Draft

By laying all of that great insulation, you’ve addressed conduction heat loss, but you might still have problems with heat loss caused by air leaks and drafts. If you have lots of insulating material, but you haven’t sealed the air leaks, then drafts can whirl around and right past your nice new insulation—and then it won’t make much of a difference. The only way to have a truly energy-efficient home is to address both problems at once. That means identifying and sealing any drafts with caulk and weather stripping, to keep the heat where it belongs—inside your home.

A Penny Saved…

Better Insulation is perhaps not the prettiest upgrade you can do to your home. However, upgrading insulation can do for you what a lot of other, more glamorous upgrades cannot: Save you money, month after month, year after year. And you can take that to the bank.

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Author: Robert Bundy