Cost & Performance of Home Insulation Options

Is your home ready for the blustery winds and frigid temperatures of winter? If you’ve spent one too many chilly winters at home, maybe it’s time to think about adding more home insulation.

Insulation serves a few purposes. It helps block the transfer of heat from a warm area to a cool one. This means in summer, it keeps heat outside. In winter, it keeps heated air inside your home. Insulation also helps block drafts. And installed correctly, it helps prevent the buildup of condensation, which happens when cool air meets warm air. (Read: Home Insulation for Comfort and Lower Energy Costs)

Here are a few insulation facts that can help you choose which product is best for your home:

Fiberglass Batt Home Insulation is Tried and True

Materials Cost: $70 – $100 per 200 sq. ft.

If you’re familiar with any home insulation products at all, chances are it’s fiberglass batts. Some brands are pink, some are white, and others are brown. But they all come in the form of rolled blankets or batts that can fill cavities in walls and between ceiling and floor joists. The R-value of fiberglass can be substantial. In a 2-x-4 wall, the U.S. Department of Energy says fiberglass can offer between R-13 and R-15. Between 2-x-6 joists, fiberglass insulation can add up to R-21.

Homeowners first need to determine the best home insulation they can afford. Most home owners can manage do-it-yourself-installation of fiberglass, especially when adding an extra layer in an attic. Just unroll, shake out very gently to fluff up the fibers, and lay in place.

There is one very important rule to know about fiberglass batts, and that’s where the vapor barrier goes. Some batts are faced or covered with paper on one side, and others are unfaced with no paper on either side. The paper is not a covering that’s supposed to face out. It’s a vapor barrier that should always be turned toward the living space to prevent moisture from getting into the insulation.

On an attic floor, this means the first layer of insulation should have the paper side facing down and the raw fiberglass side facing up. On the walls, ceiling, and floor in any other room, the paper should face the interior of the room.

Unfaced batts are bare, and have no vapor barrier on either side. If you want to add a new layer of insulation on top of an existing layer in your attic, choose unfaced batts. Adding a second vapor barrier would encourage condensation in the attic, and can cause a lot of problems for years to come.

Blown-in Loose Home Insulation Fills Voids

Materials Cost: $50 – $70 per 200 sq. ft.

It’s not necessarily a DIY job, but blown-in insulation gives you a lot of freedom. This is a great product for areas that are difficult to reach, where you need a thicker insulation layer, where corners are awkward, or any place where carrying and rolling out a batt is not preferable or feasible.

Blown-in home insulation, which is often treated cellulose, rock wool, or fiberglass, comes in compressed blocks. Installation requires a blower machine. Chunks of insulation are broken off and dropped into the machine, where they are fluffed up and blown through a large, flexible hose.

This is usually a 2-person job, with one operating the machine and the other handling the hose and application. You can rent one of these machines if you’re handy and would like to try it yourself. It's not recommended because you can easily blow in too much insulation which will cause other problems. For example, in the attic you can block the soffit vents which you need for ventilation, to rid the attic of moisture.

Sprayed-in Foam Insulation Covers Completely

Materials Cost: $200 – $300 per 300 sq. ft.

If you’re in the construction phase with your home, or if you need a major insulation overhaul and don’t mind damage to the walls and ceiling, sprayed-in foam insulation covers better than anything else. Known as “Icynene,” this home insulation acts as its own vapor barrier, blocking all air from passing through. To learn more about the different types of spray foam insulation, open and closed cell, review this EPA information on spray polyurethane foam products.

Sprayed-in insulation starts out as two chemicals, which are mixed together as they’re sprayed. What begins as a thin layer of foam rapidly expands to fill or overfill the cavity, depending on your needs. Because of the thickness, foam has the potential to give the highest R-value. It’s rated at approximately 6.2 for every inch of thickness.

In a new-construction home, the foam is sprayed between joists and studs, where it expands. Once the foam hardens, the excess is shaved or trimmed off, leaving the insulation as a perfect fit.

Because of the inherent vapor barrier quality, there is a widespread debate on whether it’s appropriate for an attic ceiling. In theory, foam could allow condensation to form underneath the shingles, where the damage could go unnoticed until the damage is extensive. But in practice, the foam seals the area so effectively, condensation may never have a chance to form at all.

Rigid Foam Board Insulation Adds Comfort

Materials Cost: $100 – $135 per 200 sq. ft.

Rigid foam board insulation isn’t intended as a sole layer of insulation. The R-value isn’t high enough. The material offers the same potential R-value as sprayed-in foam, but the sheets are usually about 1/2 to 1 inch thick.

This material is very effective for insulating underneath siding, inside basement walls, and in certain other areas that will vary depending on the construction of your home. Rigid foam board is one of the most expensive options, but anyone can install it. The panels are lightweight, the edges are tongue-and-groove to interlock, and they fasten with special screws that have a large plastic washer.

Insulation is one of the best investments that you can make. It helps reduce heating costs in winter, cooling costs in summer, and it makes your home more comfortable. If you’re not sure whether your home needs more insulation, it’s time to perform a home energy audit. (Read: Home Insulation Doesn't Work by Itself) It’s simple, and the results can help save you money now and for years to come.

*Average insulation costs sourced at Homewyse.com.