What is the safest insulation to use?

Real Wool, Mineral Wool, and Fiberglass Blown-In Mineral wool and real wool blown-in are less common but are healthier choices.

mychemicalfreehouse.net - Non-Toxic Insulation: A Complete Guide - My Chemical-Free House

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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. Also, flame retardants and mildewcides are not counted as VOCs.

Green Certified?

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 as of 2021. 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 zero-VOC product. The types are outlined below organized by where they are used in the home, and in the order in which I would consider them. 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.

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. It’s not actually my top pick in the batts category. 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 the following brands are now extremely low in VOCs.

Formaldehyde-Free Fiberglass Brands:

1. Knauf EcoBatt is recommended by many extremely sensitive folks who could not tolerate polystyrene, cotton, or wool. They are formaldehyde-free and they use a starch based binder listed on their declare label. Other ingredients include ammonium sulfate (fire retardant), mineral oil (dedusting) and silane. 2. Owens Corning Pink Next Gen (formally Ecotouch) fiberglass insulation has GreenGuard Gold certification. The binder is formaldehyde-free and appears to be starch based. All ingredients except the surfactant and pink dye are listed: vegetable oils, sodium lignosulfonate, silane. 3. Certainteed Fiberglass insulation is also made with a undisclosed plant-based binder. It’s listed as “sugars” in the EPD along with citric acid, mineral oil, silane and an undisclosed additive. 4. Johns Manville Fiberglass insulation is GreenGuard Gold and uses a formaldehyde-free acrylic binder. A patent by the company that is likely related to this product can be found here.

Are there Flame Retardants in Fiberglass?

Knauf lists ammonium sulfate which is used as a flame retardant, Owens Corning lists no flame retardant, Certainteed doesn’t list a flame retardant but they do have an undisclosed additive.

Blown-In Fiberglass

Blown-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 blown-in, but I don’t see the ingredients for that one, so I cannot compare it to the other two.

Fiberglass Insulation Around Pipes

The fiberglass insulation for around pipes that I have seen is also formaldehdye-free.

R-Value 3.5 inches is R-11-R-15.

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 it is the most obvious alternative to fiberglass. It is also 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

1. Rockwool (formerly Roxul) is the most common and accessible mineral wool insulation. They have a newer version, called AFB evo, that does not contain formaldehyde. The binder appears to be starch based. 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 is the type for perimeter exterior walls, Safe N Sound, their soundproofing version is for interior walls, and ComfortBoard is exterior insulation (outside of the sheathing). All three contain the same binders/additives: <3% phenol-formaldehyde, <1% starch, and <0.2% mineral oil source. 2. 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), the latter usually has to be special ordered through a store. They also have a blown-in option as well. 3. American Rockwool is a brand that is harder to source (in 2020 they 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.

Other Info

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.

R-Value 3.5 inches is R-15.

Cost USD (2020) $0.95/ sq ft for Rockwool (Comfortbatt, 3.5 inch)

Where to Buy Rockwool and Thermafiber at hardware stores across the US and Canada, or through your contractor.

3. Wool Batt (and Blow-In) Insulation

Havelock Wool Insulation via www.havelockwool.com

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. It’s more expensive than fiberglass and mineral wool above.

Top Brands of Wool Insulation

1. Havelock Wool has no synthetic fibers and no binders. It’s only wool and boric acid. They provide a Declare Label for all of their ingredients. This is the purest of the wool options (and really the most natural insulation all around). It’s definitely a favorite in the environmentally sensitive community. You can buy it online which makes it the most accessible wool brand. 2. Oregon Shepard is made from wool fiber, borate, sodium carbonate, and casein. 3. Black Mountain NatuWool which is 95% wool and 5% polyester binder is treated with borax. Though in some of their informational materials it says it’s treated with kaliumfluorotitanat. 4. Wool Life USA makes wool insulation treated with permethrin instead of borax acid. They claim on their site that this is a bio-based insect repellant which is not accurate.

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 did well with Havelock loose-fill. I tested Havelock and found that it did have a noticeable wooly smell, though others have barely noticed it. The natural oils of the wool have an odor that may not 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.

R-Value 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 buy Havelock online.

4. Recycled Cotton Batt

Ultratouch Insulation is what my builder used in my chemical-free tiny home. If you rule out fiberglass, mineral wool, and real wool, this would be something else to consider. It used to be made from new denim scraps, but they have moved to recycled denim now. It does contain boric and ammonium sulfate and an olefin binding fiber (similar to rayon). You have to test it 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). I would not use this insulation again due to its poor ability to hold itself tight in the walls, the potential for mold if it gets wet, and the slight odor I picked up. 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. Other Info Wear an N95 mask while cutting and installing as it does get extremely dusty when working with it.

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R-Value For the 3.5” thickness, you get an R-Value of 13

Cost USD (2020) $0.79/sq ft

Where to Buy This had to be special ordered when I built my house. Now, you can buy it at Lowes and Home Depot.

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 and who hasn’t done well with the other options above.

Brands

1. Thermo-Hemp out of Europe was one of the first brands of hemp insulation.

2. HempWool is 90% hemp and 10% polyester. Order from Hempitecture.

3. MEM in Canada makes an insulation that is 88% hemp and 12% polyester. 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! Note that Polyester is not biodegradable .

R-Value It is R-13 for 3.5 inches

Blown-In Insulation

1. Cellulose

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 House design, which has great attention to details around moisture management and green healthy materials.

It is used in both walls and attics.

Safe Brands of Cellulose Insulation

1. GreenFiber brand from Lowes and Home Depot is 85% recycled newspaper. They have a Declare Label which lists boric acid, sodium pentaborate pentahydrate, ammonium sulfate, mineral oil, monoammonium phosphate, calcium carbonate, and corn starch. 2. Ecocell makes batts that are a mix of cellulose and cotton. It also contains PET plastic, boric acid, as well as sodium poly borate, and ammonium sulfate. You can find this insulation without ammonium sulfate – that may be special order.

3. Weathershield brand by Rona in Canada.

R-Value 13.3 for 3.5 inches

Cost USD (2020) $0.32/sq ft

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 chemically sensitive people. 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 have 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 that 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-Value R-13 for 3.5 inches

Cost USD Around $2.25/sq ft including installation costs

3. Real Wool, Mineral Wool, and Fiberglass Blown-In

These three insulation types can be blown in as well. Fiberglass (pictured) is the most common blown-in insulation, followed by cellulose. Mineral wool and real wool blown-in are less common but are healthier choices.

Brand names can be found in those respective sections above.

Exterior Insulation for Houses

1. Styrofoam/Rigid Foam

i. Polyisocyanurate “Polyiso” Foam Board Insulation

Polyiso is one of the insulation types 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 building codes move towards requiring exterior insulation. It can be used in trailers and metal structures as well. It’s not to be used under slabs. Flame retardants are a bigger concern than trace pentane. The most common flame retardant is TCPP. It’s best to look for brands that don’t use a halogenated flame retardant like TCPP. Newer and safer flame retardants are non-halogenated phosphorus-based. Though the foil does block the FR, the edges are unsealed and it will never be perfect.

Healthy Brands of Polyiso Foam Insulation

1. 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 (all they have said is that it is phosphorus-based and is non-halogenated). 2. GAF polyiso EnergyGuard-NH uses a halogen-free flame retardant (which is phosphorus-based, like the Energy 3E FR 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 3. ZIP System R-Sheathing is the Huber Zip OSB sheathing, polyiso, and weather-resistant barrier all in one. Though you can use the above two brands as exterior insulation on the outside of the plywood or OSB, “ZIP-R”, as this type is normally called, is integrated with the sheathing, with the polyiso on the interior side. The flame retardant is TCPP. R-Value 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 (extruded polystyrene) is another common exterior insulation outbound of the sheathing. It is also used on exterior concrete basement walls, underneath 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. HFCs contribute to global warming. Changes started January 1st, 2021. Eleven states have banned foams blown with HFC-134a and other high-GWP blowing agents, including HFC-245fa as of January 1st 2022. A ban on high-GWP blowing agents also went into effect in Canada on Jan. 1, 2021. Canada did not ban HFC-134a but created maximum GWP for foam blowing agents. Ownings Corning doesn’t use HFC-134a (GWP of 1430) anymore, they now uses a hydrofluoroolefin (HFO) blowing agent with a GWP of less than 80. And DuPont now offers a reduced GWP foam available in Canada and HFC-regulated U.S. states. The blowing agent is not disclosed. They say that the GWP was reduced by 20%+ (source, source, source). 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. Most are now using a butadiene styrene brominated copolymer as the flame retardant (Source). DOW lists a brominated flame retardant (FR122P) in some of their XPS.

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.

R-Value R-5/inch

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 there.

R-Value R-4/inch

Cost by R-Value (R6) R-6 is $1. 24 sq ft

3. Cork

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 odor 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.

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See this post as an example or cork used as the facade.

R-Value R-4/inch

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. The total VOC level is 187 μg/m3.

R-Value R-3.7/inch

Cost R 5.8 is $1.81/sq ft

Insulation Typically Used in Trailers, RVs, and Vans

1. Rigid Foam

EPS (Expanded Polystyrene aka Styrofoam)

EPS (expanded polystyrene) 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 on the interior, and under the slab. Though you are far more likely to see the XPS type of styrofoam under a slab.

Blowing Agents

EPS usually is made with pentane as a blowing agent, the final product has trace amounts of pentane which dissipates rather quickly and completely. Some butane can also be used as a blowing agent. Sometimes the only blowing agent is carbon dioxide (based on DOW xnergy Declare label).

Zero-VOC

EPS, despite the name (polystyrene), does not offgas styrene under normal conditions.

It is considered 0-VOC (and pentane and styrene are not exempt from the VOC testing).

What about Styrene?

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 acidic beverages out of styrofoam cups. This is a very old product with a long track record. Here are a couple of links to back up the claims. In the form of insulation, I would consider this product to be non-toxic, zero-VOC, odorless, and stable, with the only risk being the flame retardants.

Flame Retardants

EPS used to be treated with hexabromocyclododecane (HBCD), but luckily it no longer is. Polymeric FR (a copolymer of polystyrene and brominated polybutadiene) is now the most common FR. The foil faces on these insulations block the flame retardants. However, the foil and plastic-backed versions can have some 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 foam to prevent ants from tunneling in.

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). These claims are disputed by Green Building Advisor and the Government of Canada. The former states that the 3/8th-inch foil has an R-value of only 1 (the same as a single pane of glass). This would hardly be useful anywhere unless it is in a curved trailer, 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.

Many similar brands can be found easily on Amazon or Home Depot.

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.

This may be ideal for small, round, and difficult to insulate places, if you can source it.

4. Thinsulate Insulation

3M Thinsulate (SM600) is an 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 for most people. The backing is polypropylene. One percent or less of the additives are proprietary and therefore unlisted. The health rating is 0 which is good. What I don’t love about using 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 people). You may find this insulation tolerable and it may be a good product for a tiny house or structure.

You can buy it on Amazon and Ebay.

R-value

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. These Panasonic panels have an R-Value of R-60 per inch. They were used in the latest Leaf House design (tiny house). This could allow you to build a tiny house for almost any climate. Though this introduces a tricky metallic vapor barrier which needs to be carefully thought out. 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 of the other options.

6. Non-Toxic Spray Foam Insulation

Spray foam that is 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 correctly. 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 no-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 if this goes wrong, as the VOCs will soak up into other materials. This has happened to two of my clients.

Brands:

Icynene and Demilic are both 2-part polyurethane spray foam.

Whether they have soy or castor oils in them is insignificant in my overall view. Icynene OC No Mix is still a 2-part polyurethane foam and although it appears to mix in the gun, the installation still has to meet all of the other parameters.

One part polyurethane:

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 and risks as the 2-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 in some of its lines and Handi-Foam has declined to answer whether it contains a flame retardant or not. Instead of using spray foam around windows and doors you can fill in the gaps with Backer Rod and seal with non-toxic caulk if needed. I have a post on caulking if you need to test multiple brands. Corinne Segura is a Building Biologist Practitioner with 8 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!

mychemicalfreehouse.net - Non-Toxic Insulation: A Complete Guide - My Chemical-Free House