Blown-In Insulation near you

Cellulose is recycled paper fiber treated with fire retardants; blown fiberglass is spun glass fiber. In an open attic they behave similarly enough that installers usually pick by habit and local price. In a closed wall cavity the target densities differ substantially, and DOE's guideline puts both numbers in writing: 3.25 to 4.0 pounds per cubic foot for cellulose, 1.6 pounds per cubic foot for blown fiberglass. A dense-pack job done below its target density will settle and leave a gap at the top of every cavity, and nobody will see it.

Cellulose carries a federal safety standard that fiberglass does not. CPSC's interim consumer product safety standard at 16 CFR part 1209 prescribes flame resistance and corrosiveness requirements for cellulose insulation that is a consumer product, and applies both to material sold to consumers for their own installation and to material distributed for installation by professionals. The standard applies to cellulose insulation manufactured after October 15, 1979. The residential code picks this up directly: Seattle's adopted residential code requires cellulosic fiber loose-fill insulation to comply with CPSC 16 CFR parts 1209 and 1404, and requires each package to be clearly labeled accordingly.

The code also sets a floor for anything left exposed on an attic floor, requiring exposed insulation materials installed there to have a critical radiant flux of not less than 0.12 watt per square centimeter, tested in accordance with ASTM E970.

This is a small federal requirement that almost nobody knows about and that tells you something about the crew. CPSC's rule at 16 CFR part 1404 requires manufacturers of cellulose insulation to label every container with a caution notice, and the label text ends with a line addressed to the person doing the work: Request to Installer: Remove this label and give it to the consumer at completion of job. If you have cellulose blown in and are handed nothing, ask.

The warning itself is about heat, and it explains two of the most common causes of attic fires after an insulation job. The required label tells the reader to keep cellulose insulation at least three inches away from the sides of recessed light fixtures and not to place insulation over such fixtures so as to entrap heat, to keep the insulation away from exhaust flues of furnaces, water heaters, space heaters or other heat-producing devices, and to use a barrier to permanently maintain clearance around these areas. It also directs the reader to check with local building or fire officials for guidance on installation and barrier requirements.

CPSC's own explanation of why the rule exists is worth knowing: the Commission determined that fires can occur where cellulose insulation is improperly installed too close to the sides or over the top of recessed electrical light fixtures, or too close to exhaust flues, and that these fires may result in serious injuries or deaths, even where the insulation itself complies with the flammability standard. A compliant product installed carelessly is still a hazard.

The FTC's rule on the labeling and advertising of home insulation, at 16 CFR part 460, puts specific obligations on installers, and it is the cheapest quality check available to a homeowner. Section 460.17 requires an installer to give customers a contract or receipt for the insulation installed, and for loose-fill the receipt must show the coverage area, the initial installed thickness, the minimum settled thickness, the R-value, and the number of bags used. For insulation other than loose-fill and reflective products, it must show the coverage area, thickness and R-value. The receipt must be dated and signed by the installer.

The rule also closes two arithmetic loopholes that inflate what a job appears to deliver. Where insulation is installed in more than one part of the house, the data for each part must be shown, and the rule states you may not add up the coverage areas or R-values for different parts of the house. And it says plainly: do not multiply the R-value for one inch by the number of inches you installed. A quoted R-value that was reached that way is not a tested figure.

There is a step before purchase as well. Section 460.15 requires an installer to have fact sheets for the products they sell, and, before customers agree to buy, to show them the fact sheet for the type of insulation they want. Those fact sheets carry the manufacturer's coverage chart, which for loose-fill must show the minimum settled thickness, initial installed thickness, maximum net coverage area, number of bags per 1,000 square feet and minimum weight per square foot at the listed R-values. Comparing the bag count on your receipt against that chart is the single most useful thing a homeowner can do after the truck leaves.

DOE's Building America guideline describes the one-hole dense-pack method as the best practice for retrofitting insulation into the closed wall cavities of an existing home, and the sequencing is what separates a good job from a decorative one.

Some walls should not be filled, and a contractor who never says so is not inspecting. DOE's guideline is explicit that if a house has live knob and tube wiring, insulation should not be added to wall cavities, and suggests either insulating over the exterior of the sheathing with new cladding installed over it, or waiting until the electrical system is being upgraded. It also notes the National Electrical Code limits loose-fill insulation in cavities containing that old wiring.

Moisture is the second disqualifier. DOE's field inspection step says that if the condition of the facade, the sheathing, the door and window framing or the interior wall finish indicates moisture problems, do not proceed with the insulation retrofit until the issues have been identified and repaired. It also warns that dense-packing compresses insulation in a confined space, so cracks and other evidence of weakness in wall finishes must be addressed first, because further damage can occur at those weak points.

Older houses carry two more flags. DOE's guidance tells retrofit professionals to assume lead paint is present in any home built before 1978, and to comply with EPA's renovation requirements where more than 6 square feet of interior or 20 square feet of exterior painted surface will be disturbed. It also notes that some loose-fill attic insulation may contain asbestos mined with the vermiculite used as insulation, which is a reason to stop and have material assessed rather than to blow new insulation over it.

Loose-fill on an open attic floor is the cheapest R-value in residential construction. It is measured by depth against a target R-value, it can be topped up later, it is easy to inspect with a ruler, and it does almost nothing for air leakage on its own, because air moves through fiber insulation rather than being stopped by it.

Dense-pack in a closed wall cavity is a different proposition. It is harder to inspect, it cannot be topped up, it requires drilling and patching, and it does meaningfully reduce air movement within the cavity when the density is actually achieved. That conditional is the whole job: the difference between a wall packed to 3.5 pounds per cubic foot and one blown loose is invisible from the outside and permanent.

This is why the verification steps matter more for walls than for attics. Ask whether a thermographic scan is included after the work, ask what density the crew is targeting and how they confirm it, and ask for the bag count on the receipt that the FTC rule requires anyway.

Quotes move on the area being covered and the target R-value or density, on whether the work is an open attic floor or a closed wall cavity, on access and whether exterior siding or interior finish has to be opened and restored, on how much air sealing and how many barriers around flues and recessed fixtures are needed first, on whether existing material stays or is removed, on the number of drilled holes a walls job needs once blocking is mapped, and on whether thermographic verification and a blower door test are included.

Two documents settle most disputes before they start. Ask to see the manufacturer's fact sheet for the product before you agree, as section 460.15 requires, and then check the finished receipt against it for coverage area, initial installed thickness, minimum settled thickness, R-value and bag count. If the receipt is missing, so is your only record of what you bought.

LokalMatch is the front end of the search. Post the job once, insulation contractors working in your area see it, and interested ones contact you directly. Pros pay for requests; homeowners use it free. LokalMatch does not install anything, does not set prices and does not endorse any company, so licensing, insurance and the paperwork above stay with you.