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Blown-in Dense-Packed Cellulose Insulation for the Roof

The roof of the new addition is being insulated to retain all the heat generated from the radiant heating system. Paul Johnson of Alpine Insulators reviews the installation process. The first step involves installing netting that is breathable so air can escape once the cellulose is installed. The netting is fire-retardant and stapled in place to hold dense-packed cellulose in place. Bales of cellulose are emptied into a machine located in an on-site truck that shreds the cellulose before pumping it at high pressure into the cavities of the roof. In this case, the insulation cost about $2.25 a square foot. Cellulose is a great thermal insulator and sound attenuator. In the interior partion wall where the bathroom will be located, cellulose will be installed directly against the drywall. Bill Hulstrunk of National Fiber reviews some of the properties of cellulose insulation, which has been around since about 1920 and used extensively since 1970 in both new and existing construction. Borates are added to make the cellulose fire-retardant, and mold and insect resistant. Because of the added borates, a propane torch can be put to the cellulose without igniting it. In a field test, a penny can be put on top of the cellulose and melted without the heat penetrating the material. These borates are naturally occurring and the cellulose itself is made of 83 percent recycled content, making this type of insulation an environmentally conscious, "green" choice. The cellulose in this house is being used in an unvented application. Because the material is packed very tightly, it reduces the chance that warm, moist air will penetrate the cavity and create mold growth.

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Blown-in Dense-Packed Cellulose Insulation for the Roof

computer-generated transcript - may not be 100% accurate

" And inside the house we've been busy insulating that new roof to keep all the heat in. Howard chose to use a natural product as well."

" Well first step is. Installing some netting. This is a cross linked polypropylene netting the most important feature of this is that it's renewable -- when we. Blow in at high pressure the cellulose because the air can come out and escape sort can be packed very densely. This -- fire retardant netting. The statement from the very tight manner. So that we can sort of we can't get a maximum."

" Cellulose in here in the truck we have insulation issues -- we empty the bales of cellulose. Where there shredded up even further and they are pumped at high pressure. Through these hoses and into the cavities. Here where we have a roof assembly with two X twelve rafters where we had strapping and we've netted over it it would cost about two dollars and 25 cents a square foot. Cellulose is not just a great thermal insulator it's a great sound attenuated in this interior partition wall of the bathroom we will be installing cellulose. Directly against the drywall. Prevent sounds from traveling from the bathroom. To the hall."

" Cellulose insulation has been around since 1920. And has been used extensively since 1970 both in new and existing construction. It's the -- borates that are active added to the material that really give it the be enhanced fire retardant. Mold inhibitors and there are repellent for insects. The key thing to know about nu wool is this isn't just ground up newspaper this has borates added that impart significant fire protection to the material. In the field we can do a task -- take hate it propane torch and put a penny on here and can melt the penny without the heat actually going through and you know heating up your hand or affecting your hand. After that cools you transcript way you know an eighth to a quarter inch of material in this fresh material underneath that. Not only do borates offer significant fire resistance but they also are mold inhibitors and resist insects. But the best thing about borates is they're naturally occurring. And that along with -- material that's made from 83% recycled content really offers an environmental -- green green product. In this house for using the -- also -- un vented to application. So first organ though maximize the potential of the depth. Thickness of the insulation I -- fully filling that cavity and then because we're dense packing her packing it in very tightly. We will eliminate the potential for warm moist air to permeate through that cavity and potentially condense and that offers the both the performance of the insulation. In the protective aspects of the material."

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Cellulose Insulation

Cellulose insulation is made of almost entirely of recycled materials, mainly newspaper. It can cover harder to reach areas such as the small gaps around pipes and electrical wires. It's treated with boric acid, which makes it flame resistant and prevents mold from growing.

Blowing In Cellulose Insulation

Bob meets up with Joe Sheridan from Energy Guard to learn more about the US Greenfiber Cocoon cellulose insulation application that is taking place in the barn. This is not a do-it-yourself process. A mesh material is first attached behind the wall cavities to hold the cellulose in place until the drywall is applied. The cellulose is essentially ground up newspaper treated during the manufacturing process with borates to resist fungus growth. It's mixed with a litle moisture and blown into the stud cavities. Product that falls onto the ground is vacuumed up and sucked back to the truck where it is remixed and blown back out. While one installer blows the insulation in, a second man follows with a stud scrubber, leveling the cellulose with the studs. The goal is to create a tight fit eliminating air movement through the wall. One can achieve an R-factor of R-13 in a 2 x 4 wall and an R-21 in a 2 x 6 wall, R-factors that will be maintained even in extreme temperatures. Within 24 hours after application the moisture content drops below 25% allowing sheetrocking to proceed. Another benefit of the product is sound attenuation. Upstairs in the attic, Joe's crew is doing a dry application. The cellulose is blown in under pressure. The hose is fed down to the bottom of the cavity and pulled back as it fills up. A proper vent in the ceiling is not necessary because the insulation is so dense that air doesn't travel through the insulation and miosture therefore never gets out to the roof sheathing. The price of the Cocoon product is comparable to fiberglass insulation.

Cellulose Insulation Installation

Insulation contractor Rick Davenport shows Bob how they install wet-spray cellulose insulation into open walls. The material is typical cellulose insulation, simply recycled newspaper. It's the installation system that is unique. Small jets of water moisten the insulation as it leaves the nozzle of the blower hose. The damp cellulose sticks to the studs and exterior sheathing, completely filling the wall cavity. The moisture will dry before the interior drywall is installed, so it doesn't harm the wall or affect the insulation value of the material. A large rotating brush, called a stud scrubber, removes excess material and cleans the inside face of the stud. In the ceiling, a blown-in-insulation is used. Plastic netting has been stretched along the bottom surface of the ceiling joists to support the material. The end of the blower hose is inserted through the netting to fill the cavity. Instead of adding water as the cellulose leaves the hose, an adhesive binder is mixed with the cellulose before it leaves the hose. The binder helps achieve a controlled density that provides a uniform insulation level of R-3.7 per inch, which comes to R-37 in this 10-inch cavity.

Insulation Basics

Here's another great tip from BobVila.com. How much insulation does your home need and where? It depends on your climate and the energy costs in your area. The basic principle is that you want to keep heat energy from doing what it does best: dissipating to colder areas. The best way is to trap a layer of air next to the heat source. In new framing, sprayed-on polyurethane foam, fiberglass or cellulose do a good job of providing this layer before the drywall goes up. If you re retrofitting your insulation, you can still spray in cellulose through holes cut from the interior or the exterior. To find out what insulation will work best in your home, you ll want to know the recommended insulation r-values in your area. R-value is the measure of a material s resistance to heat flow. The higher the value, the more effective it is. To see the recommended insulation r-values and cost estimates in your ZIP code, visit the Department of Energy s web site. Even a small draft can make your insulation less effective. Seal any gaps around electrical outlets, ducts, windows and doors with foam sealants, caulking or weatherstripping. The most important area to insulate is your attic. Make sure you ve got at least the attic floor insulated with blown-in or batt insulation to your area s recommended r-value, and consider insulating the roof and attic walls as well. This can provide a fully insulated buffer zone to keep heat where you want it and keep the lid on your energy costs. Find out more at BobVila.com: The ultimate home improvement web site! BobVila.com 2008