Below is a comparison of different insulation systems with the pros and cons of each. We have studied each and have not found a better and more affordable insulation system than the Blow-in-Blanket System (BIBS).
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The installation of the Blow-in-Blanket System is what mainly sets this insulation apart from any other system. Polypropylene netting is stapled tightly over the cavity. A hole is then poked in the netting, the hose inserted, and the cavity is filled. By blowing in the fiberglass the cavity is custom filled to the correct density by BIBS trained installers. Another higher level is attained by BIBS installers belonging to the Blow in Blanket Contractors Association (BIBCA). A BIBCA member has regular training to insure the proper installation of the system. By being a BIBCA member in good standing the fiber manufacturers will warranty the Blow-In-Blanket System insulation for the life of the building. BIBS in 2×6 construction equals R-23 and in 2×4 it is R-15 which is about as much R value as is currently available in that cavity depth. The installation is clean as the netting contains most of the fibers. Safety equipment is a dust mask, though there is very little dust. The fibers are pure fiberglass with a texture like cotton balls so it is not itchy like most fiberglass batts. The Passive House Institute US founder Katrin Klingenberg calls blown in fiberglass the most cost effective insulation. BIBS cost is typically 30% to 50% more than fiberglass batts, though this cost is a higher R-value also, and again, it fills the cavity much better.
Blown in fiberglass using the smaller fibers is also very effective in dense packing existing walls. 2.25# of fiberglass has the same or less air infiltration as cellulose, which is the other commonly used dense packing material. The fiberglass is a higher R-value and doesn’t have to be packed in so tightly as cellulose, so there is very little risk of blowing sheetrock off the wall.
One of the considerations with all insulation systems that is now being looked at is Global Warming Potential, (GWP). Fiberglass GWP is higher than cellulose but less than foams. The GWP is somewhat offset because fiberglass can last a very long time, is up to 70% recycled glass, and can be taken out of one home and put into another if desired.
The GWP of cellulose is the lowest of commonly used insulation. Except for the fire retardent chemicals, cellulose has been recycled paper and cardboard. Newsprint was a major component in cellulose, but everyone knows there is not as much newsprint as there used to be. Unused or new paper has been used to make some cellulose, which increases GWP. Lifespan of cellulose is pretty long, but how long depends on the environment it is in.
Installer experience is needed to get the right mix of chemicals at the right depth and at the right temperature of installation. Installation temperature is critical or the foam will not stick to the surface it is being blown onto. The installation also has to be done in the right way as in how much is sprayed in at one pass. Spraying foam is a chemical reaction, which means it makes heat. There have been incidences across the country of buildings burning down because the foam was not installed properly, it got hot, and it started a fire. Some building scientists do not like the practice of blowing closed cell foam into a cavity and not filling it. This can lead to moisture issues in the wall and also makes the wall assembly less effective due to wood conducting the cold through the wall. Best practices is to fill the wall cavity with insulation. The major drawback with this foam is the cost and the complexities of installation. Because it is a petroleum product the price is connected to the price of oil, and this is the costliest insulation commonly used.
The GWP of foam is high. It is also uncertain how long it will last in a home. The industry does accelerated aging tests, but in the real world it can be different. Closed cell foam can not be installed in a closed cavity, like an existing wall. The claim is often made that a blown foam home is a tight home. Not exactly. Other spots in a home must be air sealed also, not just the wall cavities. Passive Houses are tested to be the tightest homes in the world, few of them are built using foam. For more information regarding foam, go to foursevenfive.com. Under info/faq, they have some articles that are very good.
The GWP of open cell foam is high. It is a petroleum product. How long will it last? Like all foam, there have been accelerated aging tests. The problem, also like all foams, is that the companys are tweaking the chemicals a lot to change the foam for one reason or another. Foam installers claim that blowing foam in a home makes them a tight home. This is not the case, there is more to air sealing a home than sealing up the cavities. Passive Houses are the tightest homes in the world, and most use little or no blown foam.
GWP is high with Bio foam. It still has petroleum in it. Longevity is the same as other foam.When comparing all of these insulation systems to each other looking at the raw material, the manufacturing process, ease of installation, installation process, and environmental impact some things start to become clear. This cradle to grave life cycle assessment is being done now on more and more products and fiberglass looks very good in these assessments. Throw in R- value, cost and final performance and it is clear that the Blow-in-Blanket System is the best combination in most circumstances. There are some places in a home where some of these other types of other insulation can be used that would maybe be better than BIBS. However, BIBS has the right cost, R-value per cavity, environmental impact, and ease of installation to be a clear best choice. This is why the Passive House Institute calls blown in fiberglass the most cost effective insulation
Insulation R-values in comparison to each other will tell you some what how they compare but when you throw in cost, application methods, safety and the materials themselves, you get a different picture. There will be places in a home where one type of insulation is better than others. There is also a grading system for insulation in which 1 is best and 3 is worst. For all examples we will use 2×6 walls unless otherwise noted.
Fiberglass batts are the oldest insulation used now and is arguably the worst. Fiberglass in a batt varies in R-value depending on what you buy, but can be up to 3.8/” (per inch). The problem is it is very hard to install them and get a 1 rating on the job because cavities are often other sizes than what batts are and when you throw in pipes and wires into that cavity it is hard to fit them around things. Energy Star homes are not done with batts. Installers vary greatly in the time in which it takes them to install them because some are more careful than others. Fiberglass batts are generally the cheapest insulation to install.
The Blow In Blanket System (BIBS) is fiberglass blown in to a certain density, tested in the field on every job, and is R-4.23/”. This is the only field tested insulation system, and it is tested to insure the R-value. When blown in it is excellent in filling the cavity around pipes and wires and is a grade 1 insulation system. It cannot settle and does not absorb water. The Passive House Institute calls blown in fiberglass the most cost effective insulation system. Passive Houses are super insulated homes that do not need a furnace to keep them warm even in our climate. This is the biggest bang for the buck in insulation. It also works well in existing homes.
Cellulose installed in walls can be sprayed in wet or installed behind mesh like BIBS. It is about R-3.5/”. When sprayed in it is wet using water and /or adhesive. Then it is supposed to be dried before installing vapor barrier and wall covering. Settling can be an issue. Dry cellulose is blown in behind mesh but has to be dense enough to prevent settling and it is then hard to install sheetrock over it. If not done correctly settling can be an issue. It has to be a minimum of 3.5# cubic foot or it will settle according to the industry standards.
Closed cell foam is the highest R-value per inch and also the costliest. R-value can be up to 6.8/” but varies from maker to maker. It also loses R-value after initial installation depending on the manufacturer, so check what cured R-value is. This is a chemical process so no one should be around when blowing the foam and for a time afterword as breathing the chemicals is not good. It is great for sealing rimjoists and other spaces where it is hard to put an air barrier up. People are getting whole homes blown with closed cell foam but for the same cost we can put together a wall with 50% more R-value.
Open cell foam is about R-3.6/”. It costs almost as much as closed cell foam in our market but still requires a vapor retarder. It is roughly the same R-value as cellulose but is way more expensive. For the cost to the benefit, personally, there is no reason to use it in our climate.