There are so many excellent choices for non-toxic, healthy, green insulation, there should be one to fit everyone’s needs.
Look out for Greenwashing
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 2020.
What is the Safest Insulation?
Well, that depends. Technically, the options with no offgassing and no additives are the purest. But the natural odors in the organic options might not agree with everyone. Neither will the cost or availability.
Mineral wool is my top pick for most people, in most cases, because it’s simple in its composition and comes to a complete cure, leaving a 0 VOC product.
The types are outlined below by where they are used in the home and in the order in which I would consider them in.
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
1. Fiberglass Insulation
Fiberglass is the most common insulation used in standard stick-framed houses in Canada and the US. For this reason, I am starting here.
You can use it between wooden studs of a house, between floor joists and in the attic. It is used in many trailers, but I don’t recommend that.
This option has improved dramatically in recent years, and specific brands are now extremely low in VOCs.
Formaldehyde-Free Fiberglass Brands:
EcoBatt by Knauf is recommended by many extremely sensitive folks who could not tolerate polystyrene, cotton, or wool. The SDS only discloses 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 in Fiberglass Insulation?
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 in there, and when they use a biobased binder it looks like they are adding a biocide.
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 contains 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 (2020)
Knaff Ecobatt is 0.49/sq ft and you can buy it at Home Depot or through your contractor.
2. Mineral Wool Insulation
Mineral wool is my top choice for batt insulation. It is in widespread use by builders who build green or high-quality homes and is the most obvious alternative to fiberglass. It is easy to source.
- The batts can be used between wood studs anywhere in the house.
- It’s very good at staying in place with compression fitting, so it fits well between framing.
- It fits and holds up well in ceiling joists.
- It can be used in an attic if detailed really well and if you don’t do well with any of the blown-in options.
- It can be used on basements walls.
Non-Toxic Mineral Wool Brands
Rockwool (formerly Roxul) is the most common and accessible mineral wool insulation.
They have a newer version called AFB, that does not contain formaldehyde. The binder is an undisclosed polymer (a plastic, likely acrylic), it also contains mineral oil. It’s much harder to source than their standard batts.
The standard Rockwool ComfortBatt does contain phenol-formaldehyde which will cure completely and quite quickly if it’s not already cured by the time it gets to you.
Rockwool ComfortBatt which in the insulation for exterior walls, Safe N Sound, their soundproofing version for interior walls, and ComfortBoard for exterior insulation. All three contain the same binders/additives: <3% phenol-formaldehyde, <1% starch, and <0.2% mineral oil. Source.
You could try both options (the regular and AFB), but there are few situations in which the regular Rockwool does not work for someone after airing it out for a short while.
Thermafiber by Owens Corning is a brand that has a regular phenol-formaldehyde line and a formaldehyde-free line (you will see the letters FF), which usually has to be special ordered through a store. They also have a blown-in option as well.
American Rockwool is a brand that is harder to source (in 2020 they have stalled production). 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.
The fibers can cause a contact allergy if you are not using gloves, but the insulation itself is hypoallergenic for most people.
3.5 inches is R-15.
Cost USD (2020)
$0.95/ sq ft for Rockwool (Comfortbatt, 3.5 inch)
Where to Buy
3. Wool Batt (and Blow-In) Insulation
Less common and more expensive, wool batting might be the next insulation type to consider if you want a non-fiberglass option and you have ruled out mineral wool.
It can be used between wood-framed walls and in the attic floor.
Top Brands of Wool Insulation
Jeff of Safe Shelters has looked into Oregon Shepard batts and found that they add boric acid, sodium pentaborate dehydrate, and a proprietary component that includes 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.
Blown-in Wool Insulation
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 work for some 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 (2020)
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.
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).
It can be used between wood-framed walls though it does not hold itself up well in ceilings/between floor joists, especially compared to mineral wool. I personally would not use it in a basement.
Wear an N95 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 (2020)
Where to Buy
5. Hemp Insulation
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).
Companies have been coming and going out of business rapidly in the hemp insulation 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 (2020)
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 acid.
Newspapers are made with soy-based inks but they still contain many other chemicals in the inks apart from soy, and there are additional additives in the insulation, usually mineral oil.
Dense packed cellulose is often used in Passive Houses, which have great attention to details around moisture management and green healthy materials.
It is used in both walls and attics.
Safe Brands of Cellulose Insulation
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 (2020)
2. AirKrete Cementitious Insulation
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.
Some people have reported shrinking, crumbling, and trouble drying. Here is the source for the concerns.
Paula Baker-Laport continues to recommend this insulation, so I’m assuming many are still doing well with it.
It can be used in walls and roofs. (Consult with an architect when designing an unvented roof).
Non-organic options like AirKrete are more likely to be hypoallergenic.
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
These insulations can be blown in as well.
Brand names in those respective sections.
Exterior Insulation for Houses
1. Styrofoam/Rigid Foam
i. Polyisocyanurate “Polyiso” Foam Board Insulation
Polyiso is one of the types of insulation that is used on the exterior side of sheathing.
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 exterior insulation as codes move to require exterior insulation.
It can be used in trailers and metal structures as well.
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 of TCPP, as it’s safer.
Though the foil does block the FR, the edges are unsealed and it will never be perfect.
Healthy Brands of Polyiso Foam Insulation
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 instead).
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 is another common exterior insulation. It is also used on exterior concrete basement walls, under the slab, and in trailers.
XPS, like polyiso, has some “thermal drift” i.e. 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.
How Concerning are these Flame Retardants in Rigid Foam?
Flame retardants are sometimes considered non-volatile and sometimes semi-volatile. They leach out in dust form as opposed to gas. If they become dust borne in the house, the main route of exposure is hand to mouth, though you can also inhale them.
My post on Flame Retardants goes into more detail.
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 exterior insulation types to consider since they will be familiar to builders and easy to source.
The boards can also be used on interior basement walls. They are also being used under the slab, as the only alternative to foam insulation.
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 that dissipates with time, 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 Insulation
Wood fiberboard is often used in High Performance/Passive House designs as exterior insulation. It can be used closer to the interior as well.
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. It can also be used as exterior insulation, insulation over concrete basement walls, and under the slab. Though you are far more likely to see XPS under a slab.
EPS usually is made with pentane as a blowing agent, the final product has trace amounts of pentane which dissipates rather quickly and completely. EPS, despite the name (polystyrene), does not offgas styrene under normal conditions.
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 the flame retardants.
EPS used to be treated with hexabromocyclododecane (HBCD), but no longer is.
The foil faces of these insulations block the flame retardants. However, 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 Insulation
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 – that also has a disputed R-value.
3. Aerogel Insulation
Aerogel is a fairly new product – unusual, extremely expensive, and harder to source.
The term itself can refer to a variety of materials from the original silica translucent product to polymer-based products that may include the addition of fibers.
The original Aerogel insulation was, developed by NASA.
Aspen Aerogel collaborated with NASA to make their polymer enhanced aerogel combined with fibers.
Some companies are selling insulation online that they claim is Aerogel. I would look closely at what’s really in it. Look for proper studies on the R-Value of it.
They claim an extremely high R-value of R-10 to R-30 per inch.
They may be ideal for small, round, and difficult to insulate places.
4. Thinsulate Insulation
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 by many chemically sensitive).
5.2 for the 1.65 inch
NB 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. You might consider them in some trailers or metal framed homes.
They are very pricey and harder to source than almost all others.
6. Non-Toxic Spray Foam Insulation
Spray foam used to fill cavities of walls is two-part polyurethane. Some of it may have soy added, but it’s still mostly polyurethane foam.
This insulation has to be mixed perfectly, under the right conditions (there are many) and applied right. When looking for a good spray foam you are looking for an excellent installer (the best one you can find) and not a specific brand.
The companies have claimed that it is 0-VOC, or close to that once cured, but many individual tests and many individual noses of those sensitive have shown otherwise.
I know moderately sensitive folks who have looked at many houses with spray foam and been able to pick up the odor for two years.
And that’s when it’s done right. When it’s done wrong it’s a massive disaster that can end in a lawsuit against the company, plus an expensive imperfect removal of all the foam.
If you are extremely sensitive you would lose the whole house when this goes that wrong, as the VOCs will soak up into other materials. This has happened to two of my clients.
One part polyurethane, which is the canned stuff discussed below, is much easier to tolerate, it’s used in small quantities, and it doesn’t have the same challenges as the two-part foam.
Insulating Around Windows and Doors – Non-Toxic Options
Spray foam is often used around windows and doors. HandiFoam is GreenGuard Gold and will be tolerable for many folks after curing. In Canada the best source is Organic Lifestyle.
I find this spray foam to be odorless once cured.
Other brands like Great Stuff, which you can find anywhere, seem very similar to me, if not the same.
Great Stuff does contain a flame retardant and Handi-Foam has declined to answer whether it contains a flame retardant or not.
I have a post on caulking if you need to test multiple brands.
Corinne Segura is a Building Biologist Practitioner with 6 years of experience helping others create healthy homes.
Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!