Cellulose Insulation Allston MA
Designer / Architect, Remodeler
2007 Guildmaster, 2008 Guildmaster with Distinction, 2009 Guildmaster, 2010 Guildmaster with Distinction
Designer / Architect, Remodeler
2009 Guildmaster, 2010 Guildmaster
Custom Builder, Designer / Architect, Remodeler
Boston Society of Architects, National Association of the Remodeling Industry, National Kitchen and Bath Association
CSA Home Services
Custom Builder, Designer / Architect, Remodeler, Specialty Contractor
2009 CotY Awards, Build It Green, Eastern Massachusetts Chaper of NARI, NARI Certified Remodeler, NARI Green Certified Professional (GCP), National Association of the Remodeling Industry
Remodeler, Designer / Architect
2009 Guildmaster, 2010 Guildmaster with Distinction
2006 CotY Award, 2008 CotY Awards, Builders Association of Greater Boston, Eastern Massachusetts Chaper of NARI, NAHB Remodelers, National Association of Home Builders, National Association of the Remodeling Industry, National Kitchen and Bath Association, Rotary International
Designer / Architect, Remodeler
2007 Guildmaster with Distinction
More than 90 percent of the new homes built in the United States are insulated with fiberglass, but there are several other options for homeowners who want to improve energy efficiency and cut heating costs. One contender that offers several important benefits is cellulose insulation.
Although costs vary by location and even among applicators in an area, cellulose is generally priced competitively with fiberglass and is less expensive than foamed-in-place applications. Although its R-value is approximately 3.5 per inch of thickness - only slightly better than fiberglass - it is an attractive insulation alternative for a number of reasons.
It's Green. For one thing, cellulose is green. It's made of 80 percent post-consumer recycled newsprint. The fiber is chemically treated with nontoxic borate compounds to resist fire, insects and mold. The Cellulose Insulation Manufacturers Association claims that insulating a 1,500-square-foot house with cellulose will recycle as much newspaper as an individual will consume in 40 years. If all new homes were insulated with cellulose, we could remove 3.2 million tons of newsprint from the nation's waste stream each year.
It's Safe. Cellulose insulation is made of paper, but the chemical treatment provides permanent fire resistance. The fiberglass industry has warned that cellulose could burn, but independent testing confirms that cellulose is safe, and it's approved by all building codes. In fact, many professionals consider cellulose to be more fire-safe than fiberglass. This is based on the fact that cellulose fibers are more tightly packed in framing cavities, which prevents the spread of fire by choking combustion air.
It Stops Air Leakage. Perhaps most importantly, cellulose is a superb air-blocker. Air leakage through cracks, voids and gaps in the building envelope is responsible for approximately one-third of an average home's heat loss. Tightly packed cellulose provides a thermally efficient, cost-effective and comfortable solution.
According to the fiberglass industry, tests demonstrate that air leakage can be controlled with dedicated air-barrier systems. This is true. Install perfectly continuous sheathing, caulks, gaskets and sealants, and you will block air leaks effectively with fiberglass or cellulose.
The fact is, densely packed cellulose blocks air better than fiberglass, which relies on trapped air for its insulation value. Cellulose is made from wood fiber, and the cellular structure of wood is naturally more resistant to the conduction of heat. When dedicated air-barrier systems are not installed perfectly (which they seldom are), cellulose wins.
While cellulose has its benefits, it has some drawbacks as well. Wet insulation of any stripe is bad, but cellulose is hygroscopic - it's able to soak up and retain liquid water. Undetected leaks can wet cellulose, causing it to sag within framing cavities. Water leaks can compress the blanket of fiber and in extreme cases can create a void space, degrading the insulation's thermal value.
Another concern is that the chemicals used to protect cellulose from fire make it potentially corrosive in wet environments. Tests conducted by the Oak Ridge National Laboratory show the chemicals used to treat cellulose can corrode metal fasteners, plumbing pipes and electrical wires if they are in contact with wet, treated cellulose for an extended time.
The Dry-Blown Variety
Cellulose comes in two basic varieties: dry fiber, which is blown into open attics and enclosed cavities; and damp fiber, which is sprayed into open wall cavities.
Dry cellulose fiber is blown through a hose into open attics or into enclosed wall, floor or cathedral-roof framing cavities. It can be installed in new or existing structures and is popular in retrofit applications because existing wall finishes do not have to be removed to install the insulation. In addition, it is favored in attic applications because you can blow unrestricted depths of fiber to achieve deep coverage with very little labor.
Blown cellulose is installed with special equipment. DIY-savvy homeowners might be able to install blown cellulose in open attics, but not in walls or cathedral roofs. You can rent blowing machines from rental centers and building material dealers that sell cellulose insulation, but in general, this is a job for pros.
Two people are required to run the equipment. One person feeds dry fiber into a hopper, breaking up clumps of cellulose as it is passes into the blowing system. The other person operates the hose attached to the blower.
The ratio of air to fiber is adjustable, and with some experimenting the right balance is struck. This is a dusty job that requires a mask.
To blow fiber into open attic, a 3-inch-diameter flexible hose is typically used. If an attic floor is in place, the installers should remove some of the boards or drill holes at strategic locations, so the hose can be inserted into the cavities. If the floor cavities are already filled with insulation, blow an additional layer of cellulose directly over the floor sheathing to improve the level of protection.
Blowing fiber into enclosed wall or cathedral framing cavities requires a different process. A smaller 1- or 2-inch-diameter fill tube is attached to the end of the larger hose. The fill tube is inserted into enclosed cavities through a series of strategically placed holes. The general idea is to drill a series of 2-inch holes horizontally across the structural surface so the holes are centered in each framing cavity. One or more holes per framing bay are required, depending on the length of the framing cavity and the applicator's fill technique.
Although walls and cathedral roofs can be filled from the inside, typically they are filled from the outside. Pieces of siding or roofing are removed, holes drilled and insulation fill tubes inserted. Air pressure is cranked up for cavity-fill applications to provide a more densely packed injection called dense-pack cellulose.
The narrow fill tube is inserted into the holes and pushed to within a foot of the far end of the enclosed cavity. When the packed insulation becomes dense enough to stall the blower, the hose is backed out a bit and filling resumes. The process is repeated until the framing cavity is filled.
The injected fiber compacts tightly around wires, plumbing and other penetrations, providing an airtight insulating blanket with a slightly elevated R-value approaching R-4 per inch. Once the filling is complete, the holes are plugged, and the siding and roof covering are patched or reinstalled.
Before cellulose can be blown into framing for new construction, walls must be enclosed with fiber-reinforced plastic sheeting or drywall. The plastic sheeting doubles as a vapor barrier.
If you have a home that was insulated years ago with inadequate levels of insulation, you are not out of luck. Skilled cellulose professionals can snake fill tubes into a wall already filled with fiberglass batts. The installer fills the cavities in a way that crushes the existing insulation without balling up the batts. The goal on any application is to ensure complete coverage installed at a density that will not settle over time.
The Damp-Sprayed Variety
While blown cellulose is a great option for attics and retrofit applications where the dry fiber can be supported by an attic floor or enclosed wall cavity, damp-sprayed cellulose provides an effective solution for open wall cavities in new construction.
Dampened cellulose is a sticky material. It is sprayed directly into open wall cavities between the studs, right against the exterior sheathing, where it stays put. That's because while blown insulation is dry, sprayed cellulose is dampened with water. Sometimes a little adhesive is blended into the mix. It provides a solid, airtight wall cavity.
Much like its dry-blown counterpart, sprayed cellulose fiber is applied with a machine through a 2.5-inch hose. A water hose with a high-pressure nozzle resembling a pressure washer is attached to the end of the fill hose. It sprays the fiber with a mist of water as it is fired from the hose. The spray dampens the surface of the wall cavity to provide a sticky contact bond between the framing materials and the insulating fiber.
The damp fiber is applied until the wall cavities are overfilled. The walls are then scraped flat using a rotating brush called a scrubber to match the exact thickness of the wall framing.
The flow of water is adjusted by the applicator to establish an important balance. The fiber must be damp enough to stick to the wall permanently, yet not wet enough to cause moisture problems.
Adding moisture to the wall cavity is a touchy subject - one the fiberglass industry likes to promote as dangerous to structural and human health. The truth is, a bad application can be dangerous and ineffective. An inexperienced applicator can introduce an unsafe level of water into a wall system, which can result in mold, mildew and rot.
On the other hand, skilled applicators achieve an effective and safe balance of moisture and fiber, and provide a superb insulation system. A target of approximately 30 percent moisture content by weight is appropriate. Freshly sprayed cellulose should feel damp, but you should not be able to squeeze water out of it.
As the sprayed cellulose insulation dries, it stiffens and is very resistant to settling. Sprayed walls should be left open until the moisture content of the fiber drops below 25 percent. This normally requires a two-day drying period, depending on climate. The installer should check the moisture content using a moisture meter.
The good and bad news about sprayed cellulose is that an entire house can be insulated in one day, but it will be a very messy day. The inside of the house will resemble a combination of winter blizzard and coastal fog. Prior to installation, windows, doors and electrical boxes must be protected with plastic sheeting and tape. Blowing fibers can irritate the respiratory tract and eyes, so goggles and a protective mask are a must. The sea of waste fiber must be vacuumed and shoveled continuously.
Spraying damp cellulose during freezing conditions is rough on equipment, and drying time can drag to a crawl. Also, while priced competitively, damp-spray cellulose will cost a few hundred dollars more than installing fiberglass batt insulation. But the upside is worthy. Coverage is complete. There are no voids in the walls. All wire and plumbing penetrations are automatically and completely sealed.
A professionally installed application is airtight, comfortable, energy efficient and safe. On the whole, homeowners report a less drafty, more comfortable living experience. As a bonus, many people think the superior airtightness and absorptive qualities of sprayed cellulose provide a quieter indoor environment. And that's icing on the cake.
In addition to being a member of Smart HomeOwner's Editorial Advisory Board, Paul Fisette is an associate professor and director of the building materials and wood technology program at the University of Massachusetts, Amherst.