Learn about the materials, methods, and costs of this insulation solution so you can keep your home comfortable and your utility bills low.
Today’s building codes require a minimum amount of insulation in walls and attics, but older homes were often under-insulated, so the answer for some homeowners maybe blown-in insulation. Blown-in insulation consists of tiny pieces of material (think confetti) that are literally blown into walls and attics via a long hose. Keep reading to find out if blown-in insulation might be your solution to comfier conditions and lower energy bills.
1. Blown-in insulation fills between existing wall studs and ceiling joists quickly and easily.
The batt insulation is a thick piece of fiberglass or paper-based insulation that is cut to fit between wall studs and ceiling joists during new construction in order to increase the insulation value of the room. It is rarely feasible to install batt insulation in existing homes, since drywall will have to be torn down, a messy, time-consuming, and expensive process. Using blown-in insulation to add to attics and walls is much simpler, less hassle, and less expensive than installing batt insulation in existing homes.
The best thing about this type of insulation is that it can seal small gaps and spaces when it settles, filling these sneaky spots where cold air would otherwise come in, and sealing them up as it settles. Furthermore, blown insulation helps reduce sound transfer between the outdoors and the interior, so unwanted street noise is also reduced by softening the sound of blown insulation, in addition to serving as an insulating blanket.
2. Blown-in wall insulation presents some aesthetic problems, is not working well in cavities and tends to get splashed onto walls and furniture.
A hole is drilled at the top of every stud space (usually on the exterior) in order to install the blown-in insulation in existing walls, and then the insulation material is blown in using a long, flexible hose. When the hole has been filled in, it is sealed with a plug that matches the siding colour. Although the plugs are usually close to matching the siding colour, when the siding is brick or stucco, it is often noticeable to see the plugs.
Another disadvantage of blown-in insulation for walls is that an obstruction in the wall space—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.
When blown in insulation is installed for a few years, it tends to settle downward by a few inches, which causes a small area at the top of the stud spaces to be uninsulated, which in turn slightly reduces its overall thermal resistance (R-value). It is possible to add more insulation to the walls, but most homeowners choose not to do so as it is such a small area.
Consult with a professional insulation contractor
Some jobs are better suited to be handled by experts. Compare insulation quotes from local insulation companies and find the best quote that meets your needs.
3 types of blown-in insulation
What is blown-in insulation made of, anyway? 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 R-value of blown-insulation, the greater the insulating effect.
No matter what type of blown-in insulation you choose to use, not all types of blown-in insulation offer the same thermal performance, but in most cases, adding even a small amount of insulation is better than not adding any at all.
In order to manufacture this light-as-air insulation, glass is heated to a liquid, and then spun into fine fibers. After that, it is turned into a loose-fill insulation. It is estimated that loose-fill fiberglass will provide an average thermal value of 5 per inch when blown into attics and wall spaces. The higher the number, the greater the insulating effect. The thickness would need to be around seven inches thick.
5 inches of fiber glass blown-in insulation to match the insulating value of a batt of R-19 insulation (R-19 is a common batt value).One bag of loose-fill fiberglass will provide a thermal value of R-19 over a106.6-square-foot area.
- Cellulose: For eco-minded homeowners, cellulose is often the insulation of choice, because it’s made from finely shredded recycled cardboard or newspaper. This is the most common type of blown-in insulation on the market, and it’s chemically treated to resist mold and fire.
A downside to cellulose is that if it gets wet (from a leaky roof or pipe), it can lose its fluffiness and become soggy and compacted, which reduces its R-value. Cellulose insulation has an average thermal value of R-3.7, so you’d need just over five inches to equal anR-19 batt. A bag of cellulose will cover 36.7 square feet at a thermal value ofR-19.
This type of blown-in insulation is a product of blast furnace slag, a by-product of the firing of iron and iron ore. This kind of insulation is also referred to as mineral wool. In order to create an airy product similar to raw sheep’s wool, the slag is heated, combined with other minerals, and spun into a product with a thermal rating of R-
3 per inch, but a single bag will only cover 60 square feet at a thermal value equal to R-19. Due to its excellent fire resistance, rock wool is often called for in areas subject to fire codes, such as a connecting wall between a house and an attached garage, or in the floor between a garage and a FROG room (finished room over garage).
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 DIYproject.) 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 blown-in insulation costs.
Check the Department of Energy’s DSIRE website to see if you can benefit from tax credits.
4. Blown-in insulation can be purchased from lumberyards and home improvement centers.
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.
5. DIY blown-in insulation can be installed in the attic, but leave he walls to a pro.
As with all home projects, it’s only natural to wonder, “Can I do blown-in insulation myself?” 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.
There is no special skill required for this job, but you will need to crawl under low, sloped attic rafters in order to evenly distribute the insulation, and you will have to crouch under them. To ensure you are able to successfully and safely complete your attic insulation project, follow the instructions on each bag of insulation as well as the instructions on the blower.
- Recruit a helper. Someone needs to load the bags of insulation into the blower, which will remain on the floor below, while the other person distributes the insulation via a long hose.
- Don protective gear. Blowing in insulation is a messy prospect and you’ll need to wear adjust mask, protective eyewear, gloves, and old clothing that you can toss out when you’re done.
- Never stand on joists. If you stand on joists in the attic and lose your balance, your foot will go right through the drywall ceiling below. Don’t risk injury and damage to your home. Instead, position two pieces of about two-by-three-foot plywood across the joists to give you a stable standing area.
As you work you can stand on one piece of plywood as you reposition the other piece of plywood.
It is important to box off electrical boxes and recessed can lights, because insulation prevents the heat generated by the lights from dissipating. The insulation must be kept away from recessed can lights because insulation prevents the heat from dissipating. An excessive amount of heat in a recessed can light will result in a premature burnout of the light bulb.
It also presents as light fire risk because some older can lights can become very hot and ignite cellulose insulation (it’s fire-resistant, not fireproof); there’s less of a risk with fiberglass insulation, which will only melt if it gets too hot. Use scrap plywood or wallboard to build a box around each recessed light, leaving a minimum space of three inches between the light and the box.
You’ll also want to box-out around any electrical junction boxes that might be in the attic, just to ensure that an electrician won’t have to go digging around in the insulation to find them in the future.
- Use battery-operated lights to see into dark corners. Today’s LED headlamps are great for directing bright light into the dark corners of an attic, but if you don’t have one, use a portable battery-operated work light to see what you’re doing.6. Usually, blown in insulation can be effective for a while, but it depends on which type of material you use.
Though it is along-term solution for most homes, will blown-in insulation need to be replaced at some point down the road? Broadly speaking, blown-in insulation lasts anywhere from 20 years to a house’s lifetime. Under ideal conditions (e.g.,professional installation, little or no water damage, minimal settling), this insulation material will maintain most of its thermal resistance for decades.
Fiberglass insulation commonly lasts for around 80 to 100 years, but it should be checked for signs of damage around 15 years after installation. Rock wool, meanwhile, is particularly moisture-resistant and the least likely among blown-in insulation materials to require replacement across a home’s lifespan, lasting up to 100 years.
Although it’s the most eco-friendly blown-insulation option of the three, cellulose insulation only lasts for 20 to 30 years on average because of its recycled makeup and low moisture resistance. Like fiberglass insulation, homeowners should begin checking cellulose insulation in the attic for noticeable degradation around 15 years after having it installed.
7. You can remove blown-in insulation from the attic by brushing or vacuuming, but a professional may be required.
Justas DIY blown-in insulation installation is possible, it’s also feasible to remove blown-in insulation from your attic on your own—with the right tools and protective equipment. Contractors typically use large industrial vacuums for blown-in insulation removal, but it is possible to suck out all the insulation from an attic with a high-capacity wet/dry shop vacuum or HEPA vacuum.
You’ll just have to bag the vacuum’s contents more frequently until the attic trusses are clear of the insulation. Otherwise, you can rent an industrial vacuum to make the job easier or hire a professional to do the work for you (the latter will be necessary either way when removing blown-in insulation from walls).
Before you vacuum insulation out of the attic, first protect yourself: Wear long sleeves, pants, gloves, and a respirator to avoid skin or lung damage, and use a headlamp or work light so you can see what you’re doing. As is the case when you’re installing it, it’s also recommended to work with a partner when removing blown-in insulation.
If all of the insulation has been extracted from the attic, contact your local waste management authority for recommendations on how to properly dispose of your specific type of insulation, as well as instructions on how to properly dispose of your insulation.
8. Sandwiched dormers and gables are difficult to insulate.
How much does blown-in insulation cost? It depends on how it’s installed. Labor’s an important factor; contractors generally charge between $40 and $70 per hour. Labor costs are essentially unavoidable when installing blown-in insulation in walls, but that hourly fee can be ignored by DIYers who insulate their attics themselves.
As blowing machines normally cost around $100 to $200 per day, the DIY approach comes with its own costs, though, as blowing machines are normally rented on a daily basis.
Among the three options you have for blown-in insulation, fiberglass, rock wool, and cellulose are the most affordable options, with prices ranging between $0.50 and $10 per square foot, including labor. There are also rock wool products at around $1.40 to $10, and cellulose at around $2.00 to $2.30. It isn’t just materials that affect price, since the required R-values for insulation in attics and walls vary depending on the local building codes.
Attics(R-30 to R-60) often need greater thermal resistance than walls (R-13 to R-23).Coupled with the large surface area of most attics, this makes blowing insulation into the attic more expensive than blown-in wall insulation.
A trusted local insulation expert can help you find the right insulation expert and compare multiple quotes, so you can choose the best option for your project.
