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A customer was surprised that there are STC requirements for mid-floor assemblies. On this project, we have the sub floor of 14 inch joists, resilient channel, 5/8 inch drywall. What would the STC be using BATTS, and what would it be installing BIBS?
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I will soon be putting my density kit to use.
If they blow 1# per cubic foot it is R-13 and 1.8 # it is R-15.
Can they blow a higher density to make the R-20 for the 2012 IECC in CZ four?
HERS RATER, KS
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What is the STC Rating of a Standard Residential 2x4 Wall with 1/2” Drywall on both sides?
- R-11 Batts
- R-13 Batts
- R-19 Batts
- 3-1/2” BIBS
What is the STC Rating of a Standard Residential 2x6 Wall with 1/2” Drywall on both sides?
- R-19 Batts
- 5-1/2” BIBS
Thanks for your help,
Doug Kooyman, Kooyman Lumber
Can anyone advise on the STC (with BIBS) of a mid floor assembly that's 11 7/8-inch joists and 14-inch joist, 1/2 inch drywall and 1/2 inch OSB? I'd like to know how BIBS would perform in this assembly for sound control of a media room.
Guy Roline
Ecofoam Insolutions
Good Morning,
I would like to know BIBS Air Infiltration Rating or ACH, Air Changes per Hour. Can anyone give me feedback on what it is, or how I can calculate it? I recall that the Perm (permeability) Rating for BIBS is better than Open Cell Foam but I do not know what that is or if it is the same thing.
I am working with a local HVAC Contractor to promote BIBS locally. He has the Air Infiltration Rating for batts and spray foams. Also, he did not realize that the BIBS Perm Rating is better than Open Cell Foam. He uses software to calculate the size of the HVAC equipment, to forecast utility bills and etc.
Doug Kooyman
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When asked this question, Knauf Insulation representatives responded that with EcoSeal, you'll get out of it what you put into it. While it is not absolutely necessary to seal around all sides of each cavity, you will increase your effectiveness if you do. Knauf's EcoSeal earned the Energy Star rating without sealing all sides of the cavities; only the top and bottom sills. However, depending on what your goals are, you may want to go ahead and seal the entire cavity + top and bottom sills. Good air infiltration ratings can be achieved either way; but as expected, the more edges you seal the better blower door test and better air infiltration results you'll get.
Johns Manville referred us to a great piece of literature produced by our friends at NAIMA. Click here for their report on air infiltration in wood walls.
What's your advice on air sealing?
Our members are always on the lookout for good sources of technical information. Check out this site (inspectapedia.com) and let us know if you feel it's useful and accurate.
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If I blow a 2x6 stud sound wall with 5/8" rock on both sides what is the STC rating for the assembly? If I need to get to STC 45 will I need a channel on one side?
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If 6 mil vapor barrier is installed over the top of sheetrock on a ceiling, will this combination provide the same or similar air infiltration benefits as sprayed polyurethane foam?
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The Blow-In-Blanket Insulation System (BIBS) will work well under your hydronic heating tubing, but to get the maximum efficiency from the under floor insulation you will need to install a foil or aluminized paper facing directly under the heating piping. BIBS is an excellent thermal barrier, but the foil will provide a better reflective layer than the fiberglass alone can provide. Several companies make foil-faced paper just for the system you described. Check with a Blow-In-Blanket contractor in your area , or the plumber installing the system.
BIBCA Technical Team
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I work as a building inspector and am trying to determine the proper installation of soffit dams for blown in insulation for CMU construction. The only illiustrations I can find are for wood frame construction and require that insulation covers the top plate. Does the insulation also need to be installed onto the top of the block wall to ensure that there is proper insulation at the joint where the wall and ceiling meet?
As long as the following BIBS and BIBS HP parameters are met, and local code requirements are followed, the BIBS HP system can be installed in a basement application:
Requirements:
1) An approved closed-cell foam from the following manufacturers, installed at the correct thickness:
BASF Polyurethane Foam
Certa-Spray (CertainTeed)
Convenience Products Closed Cell
Fomo Magnum
* NOTE: only Convenience Products and Certa-Spray are endorsed members of BIBCA
2) An approved glass fiber from the following manufacturers, installed to the correct density:
CertainTeed’s SP (at a 2.3 lb density)
CertainTeed’s Optima (at a 1.8lb density)
Johns Manville’s Climate Pro (at a 2.3 lb. density)
Johns Manville’s Spider (at a 1.8 lb density)
Knauf Jet Stream Ultra (at a 1.8 lb density)
3) The fiberglass must be blown behind the BIBS®, BIBS HP® fabric.
It can only be secured through the R-Factor office in Aurora, CO, or one of its direct, approved, distributors.
4) There must be in installation of a Class II vapor retarder on the warm side of the wall configuration per code requirements.
5) The BIBS HP® system can only be installed by a trained, tested and certified BIBS®-BIBS HP® Contractor in good standing (current contract and certification on file at the R-Factor/BIBS office in Aurora Colorado)
If all of the above criteria is met, then it’s an approved BIBS HP® application.
codes MUST be followed in each area. BIBS in no way implies that every municipality accepts foam below grade/on concrete walls as a standard. Check with local city code offices to make sure there is no restrictions as far as this application on concrete/below grade.
Regards,
Paul Colley
North America Accounts Manager
Blow In Blanket Systems
800.525.8992 O
303.263.7143 C
303.733.0414 F
pcolley@service-partners.com
www.bibs.com
Heavy or massive objects like masonry, earth, and water can hold a lot of heat. Because of this capacity to act as a heat source
(warming their surroundings) or a heat sink (drawing heat from and cooling their surroundings), materials with thermal mass affect
comfort both indoors and out. Buildings in climates with large diurnal (day–night) temperature swings, like the high-elevation Southwest, offer a classic example of the time-lag effect of thermal mass. Adobe and other types of masonry walls absorb intense daytime heat, keeping temperatures comfortable inside. During the cold night, the walls pour out their accumulated heat, keeping the inside warm. By morning, the walls,if they are designed correctly, can again absorb the daytime heat.
In most of North America, under most conditions, temperatures vary over the course of 24 hours but stay either above or below
the comfort level. Heating or cooling is then necessary for most buildings, so building a tight envelope with materials that insulate
well, or have a high R-value, should be the top priority.
Do materials with high thermal mass also insulate well? Some manufacturers would like us to think so, wielding a metric called
“effective R-value” as evidence. And indeed, the time-lag provided by thermal mass saves energy in some climate conditions, but
the effect is very circumstantial. As a more general rule, the most effective thermal storage materials are fairly good conductors and thus poor insulators. A thermal mass like poured concrete insulates poorly with R-0.08 per inch, (compared with an R-4.2 for BIBS). But even in climates where insulation is the priority, buildings can use thermal mass. For example, night-flush cooling and passive solar heating can be viable strategies in the same location during different seasons. Using thermal mass on the interior of a well-insulated building envelope aids both strategies because the mass can absorb solar heat during the day and release it at night.
Many uses of thermal mass can reduce energy consumption and improve comfort. In buildings that are only occupied sporadically,
however, it is often more efficient to minimize the interior mass so they can warm up (or cool down) quickly when needed. Also,
thermal mass can be expensive and space-intensive, so architects and builders tend to use it where it can also serve other functions: as structure, as a durable interior surface like flooring, or in a heating system like a masonry stove.
Source: “Thermal Mass: What It Is and When It Improves Comfort.” November 2007; http://www.buildinggreen.com/auth/article.cfm/2007/10/30/Thermal-Mass-What-It-Is-and-When-It-Improves-Comfort
Good article forwarded to our office. Thanks Randy!
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What's wrong with this picture? Can you spot 4 major issues? This photo shows a representative insulation job performed by workers who used similar standards at an entire subdivision of new homes. The developer hoped that the homes would qualify for Energy Star. How many problems can you spot?
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Open- or closed-cell spray foam insulation is a great way to get air sealing and insulation in a single step, but the health implications are fuzzy
Spray foam is a great air seal and insulator, but the jury is still out on the health effects of possible fumes.
Spray-foam insulation has become a weapon of choice for many builders and homeowners trying to build tight, energy efficient houses. And with its long list of attributes, that's no wonder. It fills tiny cracks and fissures in walls and roofs to form an effective air seal. The high R-values of closed-cell foam pack a lot of punch in a small space, and closed-cell versions can block the movement of moisture into wall and roof cavities. Expensive as it may be, it's at the top of its class.
But does this miracle material have a darker side? Dan Fette's question about the potential hazards of spray foam launched an extended thread containing enough anecdotal information to give a few readers pause for thought and dissuaded others from using foam at all.
Polyurethane foam is a two-part compound mixed at the job site as it's sprayed from a high-pressure gun. Although some of its ingredients are nasty at the time of application, when it cures the foam becomes an inert material that should not off-gas any harmful chemicals. That, at least, is our common understanding and the word from manufacturers and installers.
Some dissent from the field
But that sunny expectation doesn't always pan out. An anonymous poster reported developing a serious chemical sensitivity while building an "uber-green" house, which included non-toxic wood finishes and closed-cell polyurethane foam.
"I became ill after moving into the house two years ago, and had to move out," Anonymous wrote. "Any exposure to the indoor air induces neurological symptoms...I never had these sorts of problems before that I know of."
Not far behind was Marlene, who said her 66-year-old brother had experienced a "very dire situation" after Icynene (a brand of open-cell foam) was sprayed in his house. Marlene said her brother was told he would probably have to sell his half-completed home after investing his life savings in the project.
David Posada said a strong odor persisted two months after Demilec Sealection 500 foam was sprayed into a 95-year-old house in Oregon during a retrofit. Julia, who suffers from chemical sensitivities, says her building materials consultant "won't allow her clients to use spray foam insulation of any kind."
More study is needed
William Swietlik, who identified himself as a member of the Federal Interagency Spray Polyurethane Foam Worksgroup and co-chair of the EPA's workgroup on spray foam, said that both open- and closed-cell foams are made with diisocyanates, among other ingredients, a leading cause of workplace asthma and a "well-known sensitizing toxicant to humans." He added: "Once an individual becomes sensitized to diisocyanates there may be no safe exposure level."
Swietlik said this is why occupational health authorities recommend personal protective equipment for installers, and that any unprotected workers or occupants leave the building while the foam is being sprayed and not return until "all residual vapors are ventilated and all dust particles (from shaving the finished foam) are cleaned up to safe levels."
Just what is "safe?" That's not clear. Swietlik had this to say: "The exact timing of this is not known for each specific building application as this depends on the amount of vapors and particles generated to begin with, the amount and type of ventilation, the size and configuration of the building, the foam curing factors and the installation and clean up techniques of the workers."
More reserach is needed, he said, not only on the problems posed at the time the foam is applied, but also on "whether or not there remains off-gasing from the finished foam that was applied days or months earlier that could affect sensitive, or sensitized individuals who occupy the building."
<br /> <a xhref="http://answers.polldaddy.com/poll/2710323/">Are Spray Foam's Benefits Worth The Risk?</a><span style="font-size:9px;">(<a xhref="http://answers.polldaddy.com">answers</a>)</span><br />
If spray foam is designed chemically to morph into an inert material after it cures, could the problem be the installation itself, an improper balance of Part A and Part B? This, at least, was the suggestion of David Posada, who raised the question after following two threads at sprayfoam.com.
There was no unanimity on this question, but Posada added this: "Much of the published information regarding low density spray foams addresses the low- or non- toxicity of 'properly cured' or 'properly installed' foams; little seems to be said about what constitutes a improper curing or installation, what chemicals can be released, what hazards (if any) may be present, and what remedies are appropriate."
A bad mix may be only one potential problem. A poster named B. Kolodziej recounted his experience with BASF Comfort Foam during a remodel of his California home. The installer exceeded the 2-inch per-pass maximum set by the manufacturer, which causes the foam to overheat as it cures. The result is a discolored insulation layer of insufficient density that just happens to smell like rotten fish. Although Kolodziej believes the product will work as advertised if installed correctly, he now regrets he used the stuff in the first place. Further, because the foam sticks tenaciously to whatever it's applied to, removing it will be a nightmare.
Tracy Nelson summed up the dilemma this way: "Here is the simple truth of spray foam in an existing building: Mixing this material in the field can be inconsistent and as mentioned many times above, completely depends on the skill level of the installer (don't confuse the actual person who shows up at the property with the company who sells you the product and promotes themselves as experts)."
An anonymous poster said a variety of factors affect the reaction of parts A and B on application, making it "very difficult, if not impossible, to get a full and complete reaction...so A+B seldom ever equals C."
The poster included a link to an American Chemistry Council site with information on spray foam for consumers.
Making a case for natural materials
Just what were you expecting when you chose a petrochemical over a natural insulation, like cellulose, wondered Robert Riversong?
"As I've stated more times than anyone here cares to remember, there is nothing either 'green' or healthy about petrochemical foams, or any of the 80,000 petrochemicals that never existed on earth before we created them.
"Unfortunately, most of American society is brainwashed into believing in the 'magic' of chemistry, as the advertisers and marketers have impressed on us for generations. Every product produced since the start of the petrochemical age is toxic, either to people or the environment or both."
Riversong points to studies suggesting that not enough is known of the impact on health by spray foam insulation. Moreover, he adds that the foam creates a sealed building that can't breathe, making humidity control more difficult and raising the potential for mold.
"I would suggest considering environmentally-friendly, non-toxic, fire-resistant, insect-proof, rodent-resistant, and mold-resistant cellulose, which is also significantly hygroscopic and assists with natural moisture management (as long as the thermal envelope can breath - i.e. no vapor barriers)," Riversong writes.
Where does this leave us?
The many performance benefits of spray-in polyurethane foam no doubt will continue to make it popular, particularly as the cost of energy goes up. Canadian insulation installer Dwaine doesn't dispute the problems cited elsewhere in the thread, but he also admits he is "completely in awe" of what spray foam can do.
"The blame is being laid in the wrong places," he writes. "When someone like myself sits back and reads these various comments, it is easy to see they are all for the most part human error. The biggest problem reputable companies are having right now in the foam industry is companies who are trying to make a quick buck and not follow proper manufacturer guidelines and installation instructions. I blame the governing agencies."
Dwaine thinks there are lessons to be learned from the Canadian Urethane Foam Contractors Association. Although it's not a perfect approach, it could help consumers feel confident in using foam.
Can anyone in our community of BIBS experts advise us on using BIBS in a metal building with 5’ span girts?
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Scott Gibson of Green Building Advisor asks what many homeowners want to know.
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Open-cell polyurethane foam expands dramatically as soon as it hits its target, rapidly filling wall cavities and typically mushrooming beyond the stud line. After it's firmed up, installers trim away the excess so drywall or other wall finishes can be put up.
The installer who sprayed open-cell foam into the exterior walls of Peter Halkias' house has packed up his truck and hit the road, leaving him with “bags and bags” of excess foam. Halkias knew up front that disposal would be his problem. Now he wonders what to do with it, and whether it can be broken up into finer chunks and spread over the fiberglass batt insulation already in his attic.
“Are there any code violations involved in doing this?” he asks. “The only thing I can think of is an issue of flammability. The attic is fully vented and any light fixtures located in the ceiling joist bays are rated IC and airtight. I am trying to kill two birds with one stone: Get rid of the waste and add some insulation R-value to my attic ceiling.”
It's an opening to discuss the potential downsides to spray-foam insulation.
First, will it work?
GBA senior editor Martin Holladay doubts much will be gained by Halkias' plan. First, exposed foam is a fire hazard, Holladay said, and used in this way it won't offer much in the way of insulation: “Unlike undisturbed foam that is sprayed in place, broken pieces of cured foam provide no resistance to air flow,” he wrote. “I doubt whether they provide much R-value, since air can easily pass through the broken pieces of foam.”
However, Bill Clark disputed Holladay's advice. According to Clark, many spray foams are approved for use in attics without any fire coating. As to the insulation value of the offcuts, Clark said, “Excess cut-off spray foam insulation will generally NOT allow air to pass through it, and even if it does, all traditionally used insulation products except spray foam allow air to move through them.”
John Klingel wondered whether the pieces of excess foam could be pitched into the hopper with cellulose and blown in over the fiberglass batts. “I would guess that the foam being shredded and mixed with the cellulose would at least postpone its getting to the landfill," Klingel wrote, “and in the meantime it could be doing some good. No?”
Actually, no, said Katie, who identifies herself as a spray foam contractor. Katie backed up Holladay's analysis. “We wouldn't recommend shredding up open-cell waste and putting it in your attic (or anywhere, really), for all the reasons discussed: fire hazard, no air barrier, no insulation value,” Katie wrote. “Plus, dust particulate would be an issue. We once tried putting open-cell waste in our fiberglass blowing hopper to shred it up and blow it in an open space just to see what would happen and if it could be done. The hopper reduced the insulation to fine pellets and there was a ton of dust. Hardly worth the time or effort to ‘recycle’ the foam when the only thing you'll gain is a fire waiting to happen.”
Whose responsibility is it?
Halkias wrote the contractor stipulated in his contract that he would bag the waste and clean up the site, but would not be responsible for disposal. “This being my first spray foam experience, I did not realize the waste that would be generated,” he said.
Whether the contractor was upfront about it or not, leaving waste materials behind for the homeowner to deal with seems an odd exception in the building trades. Offcuts from framing lumber, drywall scraps, plumbing and wiring odds and ends and all the other debris from construction is usually taken away by the sub, or at least pitched into an on-site Dumpster by the general contractor.
“I think that any spray foam contractor who doesn't take responsibility for job waste is irresponsible,” wrote Holladay. “One way of shaming this contractor is to name the company and the city. Any company that claims to be environmentally responsible should have a waste disposal plan,” he added. “If a contractor's routine work generates waste, then disposing of that waste in a responsible manner should be part of the contractor's routine services — in my opinion.”
“Every construction or remodeling contract should end: ‘The site will be left broom clean,’ ” said Robert Riversong.
But maybe the practice is common in some areas. John Brooks said the practice of charging to haul away foam waste is common in North Texas, according to the contractors he's spoken with. “The amount of waste with an open-cell job can be LARGE,” he said. "Not only is there a FEE ... there is a high volume of foam filling up the landfill.”
What should be done with scrap foam?
“Open-cell spray foam is mostly comprised of air and is completely safe to take to a landfill,” said Clark, whose post includes a link to Spray Foam Energy Solutions, a California company. “It will crush down to almost nothing when driven over with tractors commonly used to compact the waste stored there. Contrary to common belief, there is very little decomposition going on in the landfill except for food waste as a few minutes with Google will attest.”
And that's the problem, said Riversong.
“Plastics last virtually forever in landfills and elsewhere in the environment, including the great Atlantic and Pacific garbage patches, where they do break down in size, becoming smaller and more dangerous to the biosphere," Riversong added. "Green materials compost back into their natural constituents and become food for new life.
“And you're completely wrong about pieces of cured foam acting as an air barrier,” he continued. "It is an air barrier only when foamed in place or placed as a tightly-fitted and sealed rigid board.”
The potential for environmental and human damage from petrochemicals and chemical additives is troubling to some posters.
GBA advisor Michael Chandler, for instance, wrote, “The fire retardants in spray foam and board foam are a bio-accumulative neuro-toxin, so disposing of waste foam in a landfill is not doing the planet any favors.”
Like John Brooks, who wrote that he is moving away from foam, Chandler is looking for alternatives to spray foam and rigid polystyrene board in the houses he builds. “I'm not there yet,” he said, “but moving in that direction.”
Chandler attributes his change in thinking to some conversations he and his wife had with Arlene Bloom at the Build Well conference last year. “She and Theo Colburn really got me thinking about the unintended consequences of some of the chemicals we use in our pursuit of improved energy efficiency,” Chandler said.
Riversong added, “Of course we would not find ourselves so often surprised by the unintended consequences of our choices if we used the Precautionary Principle, which requires that any new thing be proven safe (and necessary) before introduction into the marketplace and environment, rather than waiting until someone discovers it to be unsafe. On that basis, it would be reasonable to assume that all 80,000 petrochemicals we've created, that never before existed on earth, are unsafe until proven otherwise.”
Industry “still in its infancy”
Some spray foam installers may be pushing spray-foam as the greenest thing since LEED, but you won't find Katie among them.
“As a spray foam contractor, we are not in the habit of buying into the 'Foam is Green' marketing ploy and do not sell it as such,” she wrote. “We install open- and closed-cell spray foam for its high insulation value and air barrier qualities (when applicable) to people who can afford the upgrade. Period. We are honest with people who are considering foam: it's expensive, it's combustible, it's plastic, and the initial off-gassing (although more dangerous to installers than building owners) during install may be a nuisance to sensitive people.”
Still, she added, spray foam has some tremendous advantages.
“The spray foam industry is still in its infancy, and there's a long way to go until it becomes a respected and viable industry, like cellulose and fiberglass have,” Katie added. “Yes, there's a lot of waste with open-cell, no matter how good an installer you are. (Waste is different than overspray, by the way.) Yes, the product can't be reused and takes up a lot of space in landfills. But what insulation is truly green? None that we can think of.”
Our expert's opinion
Here's what GBA technical director Peter Yost had to say:
Insulation value in attic: I agree with Martin and Katie; there is no net gain to be accomplished with this effort.
Responsibility: Dealing with the overspray and cut-off waste definitely is the responsibility of the installation contractor and, as Riversong stated, easily covered by the standard “broom clean” contract language. And a really good reason for this is that if the contractor has to deal with the waste, what better way to ensure that the contractor has incentive to minimize this waste?
Cutting versus “roller-shaving:” Big difference between these two in terms of dust creation when removing the overspray. The dust from roller-shaving the excess can be substantial and pervasive, making for a nuisance to most of us, and a health issue for sensitive individuals. When we used open-spray foam to insulate exterior walls in our own basement, the excess was roller-shaved. While the contractor left the basement broom clean, an acrid dust covered just about everything and proved to be a real problem for our daughter with asthma. After a full day of HEPA-vacuuming every exposed surface we were fine, but cutting at least most of the excess would have created a lot less dust.
Spray foam insulation contractor certification: In Canada, this is required. The U.S. needs mandatory spray foam insulation contractor certification to separate the wheat from the chaff.
Flame retardants: While open-cell spray foams have a good profile in terms of global warming potential they typically contain brominated flame retardants as Chandler pointed out. Selecting the most benign and highest performing insulation remains a real challenge.
I'm considering purchase of a Flir I7 thermal imaging camera. While the price seems right on this model, I'm wondering whether it has sufficient features for a BIBS dealer to gauge gaps, voids, heat loss areas. I don't want to pay for features I don't need, but don't want to under-buy either. Anybody got advice or experience on this without getting into a price discussion?
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Jeff Boone
Northstar Comfort (Wichita, KS).
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We are bidding a job that has wide exterior walls. The walls are 14 feet high. It calls for 3” of polyurethane spray foam with batts. We will also bid BIBS. We have an 8” deep space 14 feet high and a 14” space 14 feet high. Both have stud spacing of 16” on center. Should we be concerned with any settling?
Greeting BIBCA Contractors,
We have a request for proposal from a local school which has the Commercial Aluminum Glass Frames set into Brick or Masonry walls. Have any of you sold a caulking job on a School or similar commercial building like that? If yes, we would appreciate any advice you can give us. Thank you.
There is no compromise on R-value with fiber glass when installed according to manufacturers recommendations. Over-blowing is not necessary to achieve superior R-value and airflow resistance.
Fiber glass provides much higher performance levels at much lower densities than cellulose. Typical closed-cavity density recommendations for fiber glass are 2.0-2.2 pcf. Johns Manville (JM) recommends 2.2 pcf for Spider. Cellulose is typically installed at 3.5-4.0 pcf for airflow resistance purposes. Weatherization contractors are warned about blowing out wallboards at these levels.
JM test data show that the R-value of Spider remains constant past the recommended density. (See chart below) The R-value of cellulose steadily decreases at higher density levels. To achieve the recommended 3.5-4.0 pcf for cellulose, you sacrifice thermal performance.
Click Here for Charts showing data on performance of fiberglass in walls vs. 'dense pack' cellulose.
Thanks to NAIMA for providing these charts! 
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At what point does over-blowing compromise R-Value? What are the other consequences of over-blowing walls with loose fill fiberglass?
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Thinking about retro-fitting your home? Take a look at this presentation before you decide on cellulose over fiberglass.
JM Spider® Drill & Fill BenefitsMore Efficient Installation Process
- Higher installed R-values than cellulose
- Comparable1or Better2Air Resistance properties than cellulose
- Can be Installed with 5/8”nozzles through mortar joints
- Minimal or no clogging in standard 1” hoses and larger
- Less dust and less clean-up than cellulose
- Installed at Lower Densities with Less Air Pressure
- Easier to train new installers
- Easier to install without settling or wall damage
Click here to view and download the presentation
The best strategy for controlling moisture in your home depends on your climate and how your home is constructed. Before deciding on a moisture control strategy for your home, you may first want to understand how moisture moves through a home.
To help understand the principles of moisture control, you need to understand the basics of how moisture can move through your home.
Moisture or water vapor moves in and out of a home in three ways:
- With air currents
- By diffusion through materials
- By heat transfer.
Of these three, air movement accounts for more than 98% of all water vapor movement in building cavities. Air naturally moves from a high pressure area to a lower one by the easiest path possible—generally through any available hole or crack in the building envelope. Moisture transfer by air currents is very fast (in the range of several hundred cubic feet of air per minute). Thus, you need to carefully and permanently air seal any unintended paths to control air movement.
The other two driving forces—diffusion through materials and heat transfer—are much slower processes. Most common building materials slow moisture diffusion to a large degree, although they never stop it completely. Good insulation, properly installed, also helps reduce heat transfer or flow.
The laws of physics govern how moist air reacts within various temperature conditions. The study of moist air properties is technically referred to as "psychrometrics." A psychrometric chart is used by professionals to determine at what temperature and moisture concentration water vapor begins to condense. This is called the "dew point." By understanding how to find the dew point, you will better understand how to avoid moisture problems in your house.
Relative humidity (RH) refers to the amount of moisture contained in a quantity of air compared to the maximum amount of moisture the air could hold at the same temperature. As air warms, its ability to hold water vapor increases; this capacity decreases as air cools. For example, according to the psychometric chart, air at 68ºF (20ºC) with 0.216 ounces of water (H2O) per pound of air (14.8g H2O/kg air) has a 100% RH. The same air at 59ºF (15ºC) reaches 100% RH with only 0.156 ounces of water per pound of air (10.7g H2O/kg air). The colder air holds about 28% of the moisture that the warmer air does. The moisture that the air can no longer hold condenses on the first cold surface it encounters (the dew point.) If this surface is within an exterior wall cavity, wet insulation and framing will be the result.
In addition to air movement, you also can control temperature and moisture content. Since insulation reduces heat transfer or flow, it also moderates the effect of temperature across the building envelope cavity. In most U.S. climates, properly installed vapor diffusion retarders can be used to reduce the amount of moisture transfer. Except in deliberately ventilated spaces, such as attics, insulation and vapor diffusion retarders work together to reduce the opportunity for condensation in a house's ceilings, walls, and floors.
To effectively control moisture in your home, you need to first consider your climate when exploring your moisture control options.
The US Department of Energy agrees with our message. It is not enough to insulate with a good system such as blown in fiberglass (BIBS). Air leakage, or infiltration, occurs when outside air enters a house uncontrollably through cracks and openings. Properly air sealing such cracks and openings in your home can significantly reduce heating and cooling costs, improve building durability, and create a healthier indoor environment.
It is unwise to rely on air leakage for ventilation because it can't be controlled. During cold or windy weather, too much air may enter the house. When it's warmer and less windy, not enough air may enter. Air infiltration also can contribute to problems with moisture control. Moldy and dusty air can enter a leaky house through such areas as attics or foundations. This air in the house could cause health problems.
The recommended strategy in both new and old homes is to reduce air leakage as much as possible and to provide controlled ventilation as needed.
For more information, see the following resources:
Note that air sealing alone can't replace the need for proper insulation throughout your home, which is needed to reduce heat flow.
In the last decade, manufacturers of fiber glass and slag wool insulation have diverted more than 20 billion pounds of glass and blast furnace slag from America’s solid waste stream.
Fiber glass insulation manufacturers recycle more material by weight than any other type of insulation used in the building and construction sector. In the last ten years for which data is available, nearly 9.5 billion pounds of recycled glass and nearly 11 billion pounds of recycled blast furnace slag have been used in the manufacture of fiber glass and slag wool insulation.
Click here to download new CSI specs for BIBS and BIBS HP
Specifier Notes:
This Product Guide Specification is intended for use as a reference by architect/engineers in the preparation of construction project specifications incorporating the BLOW-IN-BLANKET® (BIBS® ) insulation system. Users must review and edit this specification for compliance with local building codes, the requirements of the project design, and for coordination with related specification sections and other construction documents.
This Product Guide Specification follows the 2004 edition of the Construction Specifications Institute (CSI) MasterFormat™, the 2008 edition of SectionFormat™, and the 2007 edition of PageFormat™. A complete listing of assigned section numbers and titles for this edition of the MasterFormat may be viewed online at www.MasterFormat.com. For use in project specifications that follow the 1995 edition of MasterFormat™, alternate section numbers are indicated with brackets.
BIBS® is a patented insulation system that blows dry white fiberglass insulation into walls, floors, attics and cathedral ceilings. The BIBS® system makes a custom filling around wiring, fixtures and irregularities, eliminating costly voids and air gaps.
The additional cost of the Blow in Blanket System (compared to conventional batt insulation) is one of the few things that you can do to create permanent energy cost savings for your home. Most people only insulate the walls of their house one time. It just makes sense to build in as much R-value as possible the very first time. BIBS is installed at a target density, (pounds per cubic foot) of between 1.8 and 2.3 pounds pcf. This compares with densities of .5 to .8 pounds pcf for fiberglass batts. Typically BIBS is installed for 1/3 to 1/2 more in cost than fiberglass batts at the lower R-value per inch. When you compare the small increase in cost to 3 to 4 time the amount of material installed, BIBS is a great value and the best choice when considering an upgraded insulation system.
As one of the most thoroughly tested insulation products on the market, fiber glass insulation products are well known products and the industry stands behind them as safe to manufacture, install and use when work practices are followed.
In contrast, there has been very limited health and safety research on other types of insulation, making the possibility of significantand unexpected health risks far greater as research develops.
An inadequately tested or analyzed product should not be deemed safe or free from health risks simply because its manufacturer has refused or failed to test its product.
Failure of a product to be adequately tested by its manufacturer should be a critical factor in determining that a product should NOT be considered for use. Dr. J.M.G. Davis of the Institute of Occupational Medicine Ltd. reaffirms this concept in the following statement: “It is disappointing to find that…some fibre products are being manufactured and promoted as safe when this really means they areuntested.
A current example of this concerns the increasing use of materials based on cellulose fibres.” Davis’ statement is equallyapplicable to all other types of insulation. JMG Davis, “The need for standardized testing procedures for all products capable of liberating respirable fibers: the example of materials based on cellulose,” British Journal of Industrial Medicine, 1993: 50: 187-190.
Fifteen years later, cellulose insulation manufacturers have still not adequately tested their products. When you choose BIBS, you are choosing a laboratory and time-tested system with decades of success as a healthy, affordable insulation system.
I have a 1956 ranch w/ hip roof that I'm going to re-insulate attic. I plan to remove all existing insulation because it's very deteriorated and installed completely wrong. Question is, if I get the attic down to nothing but bare ceiling (rock lath) and cavities, what would be the best way to insulate it to R49? I thought foam first to provide a nonstop vapor barrier and better seal than I can achieve with poly, then blow in fiberglass up to the R49. Am I on the right track, or is there a better method? I'm getting totally conflicting advice from insulation contractors around here in Iowa. Thanks for your advice, I want to do it the right way.
Steven
We are currently working on a new roof design for our buildings using a prefabricated truss system. Our homes are multifaceted and circular which results in trapezoidal roof sections. Blow in insulation would be an ideal product, however because we are using trusses the roof is 18” deep. I believe that standard practice for blow in on vaulted ceilings is to fill the roof, ie. no air space. Can we use blow in insulation for a vaulted ceiling and keep an air space in the roof?
Recently, I had the BIB system placed in my attic area. Some of the finished work contain a silver insulated covering--especially on the larger areas. I do not see this in your videos. Are the eves of an attic insulated? Also, will this insulation collect moisture and mold? Is the BIBS system easily removed?
Claudia
