Let's learn a little terminology so that we can understand how to rate insulation and now it works.

What is R-Value?

Think of "R"  as standing for resistance. The R-value is a measure of how well a material resists the passage of heat. The higher the R-value, the more effective insulation. Insulation should always be judged by R-value rather then in terms of inches. Different types of material can and often do have a different R-value even though they are the same thickness.

I have heard of U-value, is this the same thing?

No, U-value is how we measure the thermal transmittance through a material. In the case of windows, we want to know how much heat (in the summer) is getting throw the window....or how much cold (in the winter) is coming through. The lower the U-value, the better the window.

How much Insulation do I need?

Well it depends on what part of the country you live. In North Carolina, R-19 is sufficient for the floor, in Minnesota you need at least R-38. You can check your local / state building codes to determine your insulation requirement.

What materials are available to insulate my house and which one is the best?

The basic categories are; batts and blankets, loose-fill, blown-in, plastic foam, rigid boards and reflective insulation.

Batts and blankets are the most common to homeowners. The main insulating material is mineral fiber-- either fiberglass or rock wool fibers.

Batts are sold as pre-cut strips and blankets as continuous rolls. Both are sold in widths that match conventional wall-stud and ceiling-rafter spacings, typically 16 inches on center. They are sold both with and without kraft or reflective foil/ vapor-retarder facings. (A vapor barrier is faced toward the warm-in-winter side)


Loose-fill insulations, meant to be poured, stuffed or blown in place, are made from several materials: glass and rock wool fibers, cellulose fibers, and expanded vermiculite and perlite. The latter two are primarily used in foundation walls.


Cellulose insulation is made from recycled paper (mostly newspaper) and wood fiber that has been treated with a fire retardant. It's used in both attics and walls. There is less liklihood of air pockets and cellulose typically have a higher R-value and better fire resistency.

 Effectiveness  of any insulation is directly related to its proper installation,  it's usually best to have this done by a pro.

Foamed or sprayed-in-place insulation (typically polyurethane) is installed by professionals who have special equipment for monitoring the mix and application. It provides very high R-values, doesn't shrink or settle once in place, blocks drafts caused by air infiltration because it conforms to every nook and cranny and offers a barrier to moisture. Sprayed-in-place types are designed for new construction and can be used in walls, beamed ceilings and around the foundation's perimeter. They are relatively expensive. NOTE: Urea-formaldehyde foam-in-place insulation should not be used because of potentially dangerous vapor emission. Do not use foam insulation around windows, they often will expand causing the window jambs to be displaced making it very difficult to open up your widow sash.

Rigid foam board insulations are made from a number of different materials: asphalt-impregnated fiber board, polystyrene, polyurethane and polyisocyanurate. Rigid panels are generally used in new construction (or re-siding and re-roofing) where they may be installed as wall or roof sheathing. They are also used beneath interior walls or around foundations. Because they are classified as combustible, they cannot be left exposed indoors. The panels may have foil facings on one or both sides to reflect heat.
 

We do not recommend using rigid board insulation on exterior walls, especially with vinyl siding, because of its lack of structural integrity. You can often look down the side of a wall and see the "wave effect" that these "rigid panels" will produce. You will hear siding companies brag about re-siding an older home and giving it a better insulation value. This is very misleading to say the least. Rigid insulation offers very little R-value to a home. It is nothing more then a scheme to justify some outrageous siding price.

If your house needs to be insulated then don't rely on a rigid insulated panel to meet your needs. See chart to the right.

Reflective insulations, made from aluminum foil, are most effective in hot climates at blocking radiant heat. Effectiveness depends on whether the foil is simply a flat sheet, used to block heat transfer through roofs, or a barrier that has multiple layers separated by air spaces, appropriate for reducing heat gain through roofs, ceilings, walls and floors.

Can I do this myself?

Yes, however proper installation determines its effective R-value. With the exception of small jobs, Insulation companies can typically provide and install insulation cheaper then Do-It-Yourselfers. Any savings are fairly minimal and quite frankly not worth the time.

As you can see, rigid board (fiberboard sheathing) is a joke. Most of the sheathing is 1/2", which give you a R-0.66 value.

Sprayed in cellulose insulation in one of our homes.

We use Safe Insulation, visit their website for more information.

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