By Glenda Taylor and Bob Vila | Updated Oct 5, 2020 5:09 PM

Layering on sweaters is one way to stay warm in a poorly insulated house, but while you’re bundling up, your furnace is still working overtime to ward off the chill and your home’s water pipes could be at risk of freezing and breaking. Today’s building codes require a minimum amount of insulation in walls and attics, but older homes were often under-insulated, so for many owners of such homes, the answer is blown-in insulation: tiny pieces of material (think confetti) that is literally blown into your walls and above your ceiling via a long hose. Keep reading to find out if blown-in insulation might be your solution to comfier conditions and lower energy bills.

During new construction, batt insulation—thick strips of spun fiberglass or a paper-based product—is cut to fit between wall studs and ceiling joists before wallboard is put up to increase insulation values. Installing batts in most existing homes, however, is rarely feasible, as drywall would have to be torn down, a messy, expensive, time-consuming proposition. Blown-in insulation can be added to attics and walls without the hassle. What’s more, this type of insulation can also seal small gaps and spaces as it settles, filling these sneaky spots where cold air would otherwise come in. And in addition to creating an insulating blanket, blown-in insulation helps reduce sound transfer between the outdoors and the indoors, so unwanted street noise will also be softened.

RELATED: 7 Places That Could Use More Insulation—and Why

To install blown-in insulation in existing walls, holes are drilled at the top of each stud space (usually on the exterior), and material is blown in via a long, flexible hose. The hole is then sealed with a plug that matches the siding. While the plugs are closely matched to the color of the siding, if the siding is brick or stucco, the plugs are often noticeable.

Another disadvantage to blowing insulation into wall spaces is that an obstruction in the wall—such as a drainpipe, an outlet box, or any other type of unseen barrier (for example, a cross-board between studs the builder might have added for stability)—can keep the insulation from filling the entire stud space, leaving a void with no insulation.

After a few years, blown-in insulation tends to settle downward by a few inches, which slightly reduces its overall thermal resistance (known as R-value), because it leaves a small section at the top of the stud space uninsulated. Blowing in additional insulation is an option, but most homeowners forego this step because it’s such a small area.

The three most common types of blown-in insulation are loose-fill fiberglass, cellulose, and rock wool—each with its own pros and cons. Minimum suggested insulation values vary by geographic zones, and you can find the recommended values for your region on this Energy Star map. The higher the thermal resistance (R-value), the greater the insulating effect. Not all types of blown-in insulation offer the same thermal value, but in most cases, even adding a little insulation is better than not adding any at all.

For all of the above types of insulation, hiring a professional installer will add approximately $15 per square foot in labor fees. (See below to learn about taking this on as a DIY project.) Federal tax incentives for insulating a home expired in 2011, but some homeowners can still take advantage of state tax credits, which can help offset the cost of insulating. Check the Department of Energy’s DSIRE web site to see if you can benefit from tax credits.

Bags of both cellulose and loose-fill fiberglass insulation are readily available at most lumberyards and home improvement stores. Rock wool insulation, however, may need to be ordered (from the same stores), because it’s more of a specialty item. In addition to the insulation, you’ll need a blower if you intend to install it yourself. Some stores will loan you a blower free of charge if you purchase 10 or more bags of insulation; if not, you can rent a blower from a construction rental store for about $65 to $80 per day.

Blowing insulation into walls is best left to the pros because it involves drilling into stud spaces that may contain electrical wiring and pipes. However, blowing insulation into an attic can be a DIY task. It doesn’t require any special skills but will require you to crouch under low, sloping attic rafters in order to distribute the insulation evenly. Follow the instructions printed on each bag of insulation and on the blower, as well as the tips below to help you safely and successfully complete an attic-insulating project.

Disclosure: BobVila.com participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for publishers to earn fees by linking to Amazon.com and affiliated sites.

Copyright © 2022 Acton Media Inc. All rights reserved.