There are so many excellent choices for non-toxic, healthy, green insulation, there should be one to fit everyone’s needs.
There are many new options that claim to be “green” “soy-based” or are formaldehyde-free – this does not mean that they are VOC-free or safe. Look very closely at what’s in it. Flame retardants and mildewcides are not counted as VOCs.
On top of that, certifications are not that useful: almost every insulation now qualifies as GreenGuard Gold, which for sensitive folks is not enough information.
The post includes the best of green non-toxic insulation and includes a cost comparison for 2019.
I recommend all of the products here, some products have affiliate programs and some do not. Upon purchase, I earn a small commission through affiliate links at no extra cost to you.
For assistance with choosing the best insulation for your needs, sensitivities, and budget, you can contact me for a one-on-one consult.
Options Used in Wood Framed Houses
Fiberglass is the most common insulation used in standard stick-framed houses in Canada and the US. This option has improved a lot in recent years and specific brands have become extremely low in VOCs.
EcoBatt by Knauf is recommended by a number of extremely sensitive folks who could not tolerate polystyrene, cotton or wool. The SDS claims an “inert polymer bonding agent derived from plant starches” and fiberglass.
No other materials are listed (but anything less than 1% does not need to be listed such as a possible mildewcide and or preservative in this case, see more below). They do claim formaldehyde-free.
Owens Corning Ecotouch Fiberglass insulation has GreenGuard Children and Schools certification which was the best GreenGuard certification for low emissions (now rolled into GreenGuard Gold). The binder is formaldehyde-free and “made from widely available plant materials” according to the company.
Certainteed Fiberglass insulation is also made with a plant-based binder.
Johns Manville Fiberglass insulation is GreenGuard Gold and uses a formaldehyde-free acrylic binder.
What are BioBinders?
We don’t know much about what biobinders actually are, but by looking at this patent you can tell that they look mostly safe. However, it’s hard to zero in on what it is. There are some preservatives there and when they use a biobased binder it looks like they are adding a biocide as well.
Are there Flame Retardants in Fiberglass?
Fiberglass insulation is made with boron but I don’t see any other flame retardant added, especially in the batts that do not have paper backing, and the spray in type.
Blow-in fiberglass that I have looked at recently contain borates, soda ash, lime, siloxanes/silicates/silane, mineral oil, and an unknown “anti-static additive”. Owens Corning unbonded loose-fill and Knauf Jetstream Ultra look similar. A client reported a “strong smell” from JM Climate Pro Fiberglass blow in, but I don’t see the ingredients for that one, so I cannot compare it to the other two.
3.5 inches is R-13-R-14.
Cost USD (2019)
Knaff Ecobatt is 0.49/sq ft and you can buy it at Home Depot or through your contractor.
2. Mineral Wool
Mineral wool is my top choice for batt insulation. It is in widespread use by builders who build green or high-quality homes. It is easy to source in North America.
Rockwool (formerly Roxul) is the most common and accessible mineral wool insulation. They have a new version called AFB, that does not contain formaldehyde, but it has a proprietary and unlisted ingredients and ammonia (here is the label). It’s also much harder to source.
The standard Rockwool ComforBatt does contain phenol-formaldehyde which will cure completely and quite quickly if it’s not already cured by the time it gets to you. You could try both options, but there are few situations in which the regular Rockwool does not work for someone.
It is mold resistant. I did get a rash from handling it where it contacted my skin but I did not pick up a smell/offgassing of formaldehyde.
Thermafiber by Owens Corning is a brand that has a formaldehyde-free line (you will see the letters FF) this usually has to be special ordered through a store.
American Rockwool is a brand that is harder to source. The company claims no chemical additives or binders, and that would be a bonus for the extremely sensitive. They also have a blown-in option.
An easy way to cut through mineral wool is with an electric carving knife.
This insulation has good soundproofing qualities. The Safe n Sound version can be used on interior walls for soundproofing between rooms.
3.5 inches is R-15.
Cost USD (2019)
$0.95/ sq ft for Rockwool (Comfortbatt, 3.5 inch)
Where to Buy
3. Wool Batt and Blow-In
Less common and more expensive, wool batting might be the next insulation batting to consider if you don’t do well with fiberglass or mineral wool.
Jeff of Safe Shelters has looked into Oregon Shepard batts and found that they add boric acid, sodium pentaborate decahydrate and a proprietary formulation using a natural protein.
Black Mountain adds recycled polyester and borate to their NatuWool which is 95% wool with 5% polyester binder and is treated with borax.
The purest option here will be the blow-in wool insulation. Some extremely sensitive folks have done well with Oregon Shepard blow-in and another extremely sensitive person found Havelock loose-fill had “no smell”. I tested Havelock and found that it did have a very wooly smell. The natural oils of the wool have an odor that may not be okay for many sensitive people, although it is not an additive or chemical smell.
While none of them claim organic certification, wool is one of the purest options. As for borax/boric acid, I’m mostly concerned about inhalation, ingestion, and absorption through touching eyes and mouth. I’m not very concerned about it once it’s behind the wall.
Wool in batts has R-13.7 in 3.5 inches
Blow in dense-pack R-value: can be 15.3 in 3.5 inches
Cost USD (2019)
Havelock Loose Fill is $1.97/sq ft
Havelock Batts is $1.62/sq ft
Where to Buy
Buy through local green building supply shops or ship from the closest one.
4. Recycled Cotton Batt
Ultratouch Insulation is what I used in my chemical-free tiny home. If you rule out fiberglass and mineral wool, this would be something else to consider that is low cost.
You have to test for your own sensitivities. I became more sensitive to fabric treatments after I moved into my house (and I had the type made from new scraps).
Wear a mask while cutting and installing as it does get extremely dusty when working with it.
For the 3.5” thickness, you get an R-Value of 13
Cost USD (2019)
Where to Buy
Hemp insulation is the newest alternative insulation in the North American market. It’s been used for much longer in Europe. I think it is very promising. It’s harder to source and more expensive than some of the other options in this category, but it could be really great for someone who wants something natural.
There are a few companies manufacturing it now:
One of the first ones was Thermo-Hemp in Europe.
NatuHemp Semi-Rigid panels are available in the UK and Canada. Canadian NatuHemp, which can be shipped throughout Canada and the US, is made of 88% hemp fiber and 12% polyester fiber, with no chemical binders and no off-gassing (they claim).
Sunstrand was in the early stages of production in 2018 of producing hemp insulation batts for the general market in the US. The binder is unspecified/proprietary.
Companies have been coming and going in this industry.
Ask them what they add to it, apart from hemp: alternate fibers, binders, flame retardants and if it’s organic. And always test a sample first!
It is R-13 for 3.5 inches
Cost USD (2019)
NatuHemp is $1.80/sq ft
Sunstrand batt is $1/sq ft
Where to Buy
Contact the companies on where to source it.
Recycled cellulose is an option often slated for those with chemical sensitivity. It is a blown-in insulation made with recycled newspaper that contains a fire repellent like boric.
Newspapers are made with soy-based inks but they still contain many other chemicals in the inks apart from soy and there are additives to the insulation.
Dense packed cellulose is often used in Passive Houses, which have great attention to details around moisture management and green healthy materials.
Home Depot also carries Ecocell, which makes batts that are a mix of cellulose and cotton. It also contains PET plastic, very small amounts of boric acid, as well as sodium poly borate and ammonium sulfate. You can find this insulation without ammonium sulfate – that may be special order.
Rona in Canada carries Weathershield brand.
13.3 for 3.5 inches
Cost USD (2019)
AirKrete is a cementitious blown-in insulation that claims to be VOC-free. It has passed the “sleep next to it test” of many an MCS patient.
The company, however, has declined to participate in the industry-standard VOC test as well as the proper R-value test, so there is some doubt around this product’s claims.
We don’t know what the undisclosed 2% of this product’s ingredients are, but many with severe chemical sensitivities have chosen to go with this option and done well with it.
Because it is a foam, it will get into all the cracks and crevices and therefore give you a higher “real life” R-Value than the batts, although people have reported shrinking, crumbling and trouble drying. Here is the source for the concerns.
R-13 for 3.5 inches
Around $2.25/sq ft including installation costs
Where to Source
You would have to check to see if you have a certified installer in your area before proceeding.
3. Real wool, mineral wool, and fiberglass can be blown in as well. Brand names in those respective sections.
Exterior Insulation for Houses
1. Styrofoam/Rigid Foam
i. Polyisocyanurate “Polyiso” is one of the most common types of exterior insulation.
Typical current blowing agents for polyiso are CO2 and pentane. There is some “thermal drift”, meaning the blowing agents offgas over time. The offgassing is extremely minimal.
This is going to become a very common insulation as codes move to require exterior insulation.
Flame retardants are a bigger concern than trace pentane. The most common flame retardant is TCPP. It’s best to look for brands that use a phosphate-based FR instead. Though the foil does block the FR, the edges are unsealed and it will never be perfect.
Johns Manville Foil Faced Polyiso has been the most popular brand among those who are sensitive. But they have discontinued Energy 3E which was the one made without TCPP (it used organo-phosphorus FR).
GAF polyiso EnergyGuard-NH uses a halogen-free flame retardant (which is phosphate-based, like Energy 3E was). “Unlike TCPP, the flame retardant becomes part of the polymer backbone of the insulation—so there is no free flame retardant that can leach out, according to GAF’s director of sustainability Martin Grohman. TCPP, by contrast, is not chemically bonded to the polyiso polymer, so it can more readily escape.” Source
Sheets of polyiso by these brands (and others) can be used as exterior insulation or you might find polyiso in the form of ZIP System R-Sheathing, which is the Huber Zip OSB sheathing, polyiso and weather-resistant barrier all in one.
Technically it’s R-6/ inch but it’s really about R-5.6/inch over its lifespan because it loses R-Value over time. It also loses R-value the colder it gets.
Cost by R-Value (R6)
R-6 is $0.60 / sq ft
ii. Extruded Polystyrene (XPS)
XPS can also be used as exterior insulation. XPS like polyiso has some thermal drift, some very slow offgassing of the blowing agents over time.
“Over a long period of time (50 to 75 years), the blowing agent slowly diffuses through the thickness of the foam” (source).
Typical blowing agents for XPS are CFC-12, HCFC-142b and HFC-134a, but they change their formulas over time. HFC-134a will be eliminated from extruded polystyrene by January 1, 2021.
XPS insulation was treated with the flame retardant hexabromocyclododecane (HBCD) until recently. The two main brands, Dow Styrofoam (Lowes) and Owens Corning Foamular (Home Depot) no longer contain HBCD. Many are now using a butadiene styrene brominated copolymer. (Source).
How Concerning are these Flame Retardants in Rigid Foam?
Flame retardants are sometimes considered non-volatile and sometimes semi-volatile and are found in dust form. If they become dust borne the main route of exposure is hand to mouth, though you also inhale them.
Cost by R-Value
R-5 is 0.60/sq ft
2. Mineral Wool Board
The other common and easy to source exterior insulation used in the US and Canada is Rockwool in board form.
The Rockwool Comfortboards will be used more and more as many codes across the US shift to requiring exterior insulation. Foam and Rockwool will be the two main types to consider since they will be familiar to builders and easy to source.
Cost by R-Value (R6)
R-6 is $1. 24 sq ft
Thermacork insulation, unlike cork flooring, does not contain adhesives. It is held together by compressing it with heat which releases a natural binder in the cork. The cork does give off a smoky smell as well as the natural smell of cork.
This is a newer product in North America and is more expensive than the more conventional options. If you can afford it, it is my top pick for non-toxic exterior insulation due to a lack of additives and flame retardants.
It can be used as exterior insulation or even the facade of a house which serves the purpose of siding, insulation and noise reduction. See this post as an example or cork used as the facade.
Cost by R-Value (R8)
R-8 (doesn’t come in R-6) it’s $4.93/sq ft for the insulation type (rougher than the facade)
R-8 in the facade grade, which covers your exterior insulation and your siding in one, is 10.77/sq ft
Where to Buy
You can buy this through green building supply stores.
4. Wood Fiberboard
Wood fiberboard is often used in High Performance/Passive House designs.
One popular brand in North America is Gutex. It is 95% wood (spruce/fir, post-industrial, recycled and new wood), 4% polyurethane and about 1% paraffin. Total VOC level of 187 μg/m3.
R 5.8 is $1.81/sq ft
Where to Source
You can buy this through 475.
Insulation Typically Used in Trailers, RVs, and Vans
1. Rigid Foam
If you prefer to watch a video on the three rigid foams I made this video to explain the toxins in them.
EPS (Expanded Polystyrene aka Styrofoam)
EPS is often used in trailers and can be referred to as “block foam” by the companies.
EPS usually is made with pentane as a blowing agent, the final product has trace amounts of pentane which dissipates rather quickly and so even as it breaks down it does not offgas further. EPS, despite the name (polystyrene), does not offgas styrene.
It is considered 0-VOC – pentane and styrene are not exempt from the VOC testing.
The concerns over polystyrene (Styrofoam) and styrene comes from the following a) chemicals released during the manufacturing of the product b) the product is very toxic if you burn it and c) the styrene can leach if you drink beverages especially hot or very specific beverages out of Styrofoam cups.
In the form of insulation, I would consider this product to be non-toxic, 0 VOC, odorless and stable, with the only risk being flame retardants. This is a very old product with a long track record, here are a couple links to back up the claims.
EPS used to be treated with hexabromocyclododecane (HBCD), but no longer is.
The foil faces of these insulations block the flame retardants if they are sealed up. But the foil and plastic-backed versions can have a strong offgassing odor. Some EPS is not backed with anything.
EPS used in packaging and cups does not contain a flame retardant, and people have sometimes been able to source this type of foam for small structures.
If using EPS in a living space I would recommend borate treated foams to prevent ants that love this insulation.
R-14 for 3.4 inches EPS.
2. Reflectix and Prodex
Reflectix is a bubble foil made of aluminum over polyethylene bubble wrap. It is flexible, very thin and claims to have a very high R-value. The thicker version claims R-21 (which is higher than 5 inches of wool).
This would hardly be useful anywhere unless it is in a curved trailer or other RV or vehicle where all other options have been ruled out. Sometimes it’s just used to insulate windows, which can be a great help.
Prodex is another similar material, foil, and polyethylene-based, whose R-value is disputed.
Aerogel is a fairly new product, unusual and harder to source. The term itself can refer to a variety of materials ranging from silica to polyisocyanate to formaldehyde. You will have to check with the company to find out what they are made of and what the VOC levels are.
Most of the Aerogel insulation brands are silica-based. I have seen some that I would expect to be very low or 0 VOC. Buy Aerogel site has foil backing which would block all the VOCs if sealed up. It does give off ammonia.
They claim an extremely high R-value of R-10 to R-30 per inch. The R-value claims are doubted by GBA. They are ideal for curved structures such as domes, arched cabins, and curved trailers. They are also very pricey.
You can find some brands on Amazon.
3M Thinsulate (SM600) is insulation used in vans, other vehicles, and RVs. It is made of polyethylene terephthalate (a type of polyester) and polypropylene fibers which will be tolerable to many. The backing is polypropylene. 1% or less of the additives are proprietary and therefore unlisted. The health rating is 0 which is good.
What I don’t love about this product in vehicles is that the insulation itself is vapor permeable and it is attached to the walls with 3M 90 Spray (GreenGuard certified, not GreenGuard Gold, not reported to be very tolerable).
R-value of 5.2 for the 1.65 inch
I have seen similar but more unusual insulation made from polyethylene and polyester for homes in batts. (It is more popular in some countries outside of North America.) It may be tolerable depending on what is added to it.
5. Vacuum Insulation Panels
Vacuum Insulation Panels have the highest insulation value of any of the insulation materials.
The foil vacuum pack will block any VOCs from migrating through, but your moisture management system would have to be planned carefully here.
These won’t work in most houses and they might not work in most trailers either.
They are very pricey and harder to source than almost all others.
Insulating Around Windows and Doors – Non-Toxic Options
Spray foam is often used around windows and doors. Handi Foam is GreenGuard Gold and will be tolerable for many folks after curing. In Canada the best source is OL. I find this spray foam to be odorless once cured.
Other brands like Great Stuff, which you can find anywhere, seem to be to me to be very similar, if not the same.
Corinne Segura is a Building Biologist with 6 years of experience helping others create healthy homes.
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