Updated Fall 2021
Testing wood glues, construction adhesives and silicone caulks was the hardest part of building my house since I did this when I was highly sensitive.
But, you’re going to need glues, caulks, and adhesives if you are building so it’s a good idea to start testing them out!
You’re going to need them for repairs and renovations too. I would suggest knowing which are non-toxic and which ones work for you before that urgent repair is needed.
This post covers low VOC, low odor, non-toxic options that are suitable for chemically sensitive or health-conscious folks.
This post contains affiliate links to products I recommend. Upon purchase, I earn a small commission at no extra cost to you.
Non-Toxic Wood Glues
I compared the odor level of these glues when wet. It is usually a better idea to sniff something dry/cured since there can be a dramatic difference between how tolerable something is wet and when cured.
Testing when it’s cured is the most important test in most cases.
Top Non-Toxic Wood Glue Brands:
Many chemically sensitive prefer this brand.
This is a PVA-based glue, with a mild acetic odor until it’s cured. PVA glues are some of the most benign. Though at my most sensitive I did not do well with this when it was wet.
Carried at hardware stores and on Amazon.
ECOS makes extremely low-toxic products, and while I didn’t get a chance to test this one, I would expect it to be good.
The ingredients are acrylic dispersion, thickeners made of cellulose and polymers (plastics), and unlisted dispersing aids.
3. Roo Glue
Roo Glue makes white glue and wood glue. It seemed totally benign when dry. It was one of my top picks when I was extremely sensitive to chemicals.
The severely sensitive might want to try this brand even though it’s special order. Otherwise, stick to Elmer’s or Titebond wood glue.
This is a PVA glue.
Available in the US and it ships to Canada from their website.
This is a brand that is often recommended for chemically sensitive folks as a safe adhesive. I had already picked Roo Glue for my chemical-free house before I got a chance to test it.
My sofa was later made with this and it worked out well for me, though I received it after it had cured.
Out of the Titebonds, Titebond III technically has the lowest VOC level of the 3 main types of this brand’s wood glues. It comes in at 5.6 g/l VOC which is extremely low.
These are PVA glues.
I would start here with the testing, since it’s inexpensive and easy to order from Amazon and find in stores.
5. Hide Glue
Hide Gue is the most natural glue option for wood. It’s made from animal protein from the collagen from skins, bones, tendons, and other tissue.
It is a strong glue with no VOCs, but it is not waterproof.
You can mix it yourself from beads or flakes for the most natural option, or you can buy it ready-made, but those do contain some additives.
The Titebond brand is a ready-made option that lists ammonium thiocyanate as an ingredient.
For the most natural non-toxic wood glue possible, this is the top choice. If you don’t need a waterproof adhesive and are not vegan, this is the healthiest option.
6. Pine Pitch Glue
Another all-natural (but not commonly used) option is a glue made of pine sap, plant fibers, and charcoal. While it’s mostly used for traditional crafts I did recently see it as s glue used in children’s toys which led me to add it to this list.
7. Gorilla Glue
I found this to be difficult to tolerate when wet, but not terrible. It seemed fine to me when dry.
This is a polyurethane glue that will offgas isocyanates until it’s cured. Isocyanates are potential human carcinogens and known to cause cancer in animals. Like many products, if it comes to you cured it may be perfectly safe.
It’s easy to find at hardware stores and on Amazon.
Non-Toxic, Low-VOC Caulks and Sealants
Which Caulks are Mildewcide Free?
Note that caulks labeled for bathrooms or as mildew resistant contain a mildewcide. Currently GE I is mildewcide free, GE II contains a mildewcide. Any caulk labeled aquarium safe is free of mildewcides, including DAP Aquarium caulk and others listed below. AFM Safecoat and Chemlink Durasil are also mildewcide-free.
Top Non-Toxic Caulking/Sealant Brands
All caulks have a chemical odor when wet. I tested them at 24 hours, 48 hours, one week, and two weeks.
If you are chemically sensitive I would recommend having a non-sensitive person put a test amount into a jar and sniff then when it’s cured.
1. Paintable Interior Caulk (White Polyether)
AFM Caulk is one of the top choices and is one of two main caulks to have on hand in every build and renovation.
I used this in my bathroom, you can use this around the shower and sink. It can be used around doors and windows and around baseboard and trim.
It’s used indoors anywhere where it interfaces with a paintable surface and is the non-toxic replacement for acrylic latex caulk.
My testing: Not the best when wet, not the best at 24 hours, but the best at one week.
Where to use AFM Caulk:
It can be used inside and outside. Around windows, cracks, tub and shower enclosures, backsplash, siding, walls and wood (like sealing molding), and general maintenance. It does not hold up as long in the bathroom as silicone with a mildewcide.
It is polyether resin (90-95%) with amino silane (1-3%) that does not contain solvents (it’s not acrylic, latex, silicone, or polyurethane). It is non-shrinking, zero-VOC once cured.
You can buy this online from Green Design Center.
Mildewcide: none. Elongation: 35%. Color: white. Paintable: yes
Alternative: ChemLink NovaLink 35 is a similar paintable elastomeric silane-modified polyether but comes in different colors (if that is needed) PSI of 145; Chemlink Durasil in white; 3M Marine Adhesive Sealant 4000 also seems very similar (polyether 15-40%, white pigments 35-70%, plasticizer 10-20%, silane 1%), PSI 220-240, and is paintable. (It retains its rubber-like odor for many months).
*note, Summer 2021 there is a polyether material shortage due to the pandemic.
2. Non-Toxic Silicone Caulks
Silicone caulking is non-toxic and highly tolerable once cured. But if you are going to be around during the application (or even within two weeks of application for the super-sensitive) be sure to pick the least toxic option.
For most new builds and renos you want one paintable caulk (polyether) and one silicone caulk from this list. Silicone is generally for kitchens and bathrooms where you don’t need a paintable surface.
Neutral cure silicone is the least toxic type of silicone – specifically oxine or alkoxy neutral cure silicones – they offgasses alcohols or methyl ethyl ketoxime not acetic acid.
Which of the two is better depends on your specific sensitivities. There is also a small chance you could find an acetic acid cure better after waiting out the cure time, which I would say is 18 days.
Oxine or alkoxy type neutral cure without added mildewcides are the least toxic types of silicone caulking.
- ASI 388 – is neutral cure (oxine type) without a mildewcide from Amazon. Lowest odor when wet.
- DuraSil – is nuetral cure (oxine type) without mildewcide, from Green Design Center.
- GE 2 Advanced – is neutral cure (alkoxy type) and is easy to get from the hardware store or Amazon. It does have a mildewcide. Very close second place to lowest odor when wet.
- Silco RTV 4500 – acetoxy cure silicone, more typical type. Very potent when wet. Though possibly preferable after 18 days of curing. No mildewcide (food safe).
Testing by the Chemically Sensitive:
Preferences between polyether caulk (like AFM Caulking, Eco-Bond, and Chemlink Clear) and silicone:
- It is possible to prefer polyether caulks (in the sections below) over silicone. You can easily have a different preference when it’s wet, compared to a few days and compared to a few weeks. Polyether can retain more of a rubber smell even after a few weeks compared to silicone.
Preferences between the two top choices of silicone:
- The choice between alkoxy and oxine would be very individual. Alkoxy (GE Advanced) smells more rubbery to me and oxine odor is difficult to describe, though it’s very subtle. Mild to modertley folks can probably choose oxine and be fine (ASI 388).
Preference between oxine and alkoxy and the more typical acetic cure silicone:
- Acetic acid/acetoxy cure silicone is VERY potent at first. It can be extremely challenging for the chemically sensitive when wet. However if we want to get into the extreme details, I found that at 18 days Silco RTV4500 food-safe acetoxy cure was totally odorless, better than the options like oxine cure (that are far less potent when wet).
Where to use 100% silicone: Windows, doors, siding, vents, around wires/pipes, in the bathroom, under countertops, around sinks, in the shower, and more.
Mildewcide: Some brands have mildewcide and others don’t. Color: Clear, white, black. Paintable: No.
This video goes over the least toxic caulking options:
What About Aquarium Caulk?
When I was building my tiny house I read that aquarium caulk (a type of silicone caulking) was the least toxic because fish are exposed to it and they can’t handle chemicals (especially biocides). It turns out that fish are a little different than people. Aquarium caulk is usually an acetic acid cure, one of the strongest odor types when wet.
It’s priced higher only because it’s marketed differently, it’s not any different than other acetic acid cure silicone without mildewcide.
I tested two brands, Aquarium Silicone Caulker (acetic acid cure) and one called Marina. Extremely potent!
Though one super sensitive person preferred the Aquarium caulk Aqueon (even though it’s an acetic acid cure) to GE I or II and Eco-bond (clear polyether). And another did well with DAP aquarium-safe silicone (another acetic acid cure, too strong for me). It’s possible to prefer these when totally cured to the options that are less potent when wet.
Marine caulking is not the same as aquarium caulk (it’s for marine applications, not fish tanks). I tested GE Marine Silicone Sealer. It had that same pungent odor though. Acetic acid smells like vinegar times a million.
It did, however, offgas quite rapidly. After one week it was at the same point as GE 100% Silicone, and at two weeks it was just as good (virtually odorless).
3. Colored Interior Paintable Caulking (Polyether)
Chemlink makes an elastomeric caulk for sealing concrete and masonry called NovaLink35.
I haven’t tested this one, but it’s a great brand and many chemically sensitive folks do well with it. This is a polyether that comes in various colors (white, beige, limestone, grey, and black) and can be used as a replacement for AFM Caulking Compound.
4. Clear Polyether Caulking
Clear polyether caulks can be a replacement for both clear silicone or paintable caulking like typical acrylic caulks (like ALEX brand) or white polyether.
The brand Eco-Bond (now out of business) was a top favorite among the chemically sensitive. The closest formula to Eco-Bond is Chemlink Clear, a similar clear polyether that is low odor.
Caulking Materials – What Caulks are Made of?
Polyurethane caulks – Usually contain isocyanate. This type smells strongly like typical fresh paint, and takes quite a long time to offgas. They can be made without solvents. If they do contain solvents it would typically be mineral oil, toluene, or xylene. It’s not used as widely as the others. I tried Loctite PL S40.
Acrylic Latex caulk – They have the mildewcide octhilinone or carbendazim in them as well as a benzoate plasticizer (which has largely replaced phthalates) and naphtha (source). They are often water-based but still could contain mineral spirits, mineral oil, and propylene glycol (source). Painters caulk are usually acrylic latex and are sandable and paintable.
I tried DAP Dynoflex 230 latex caulk and DAP Alex Plus, an acrylic latex with some silicone. At one week they both had more offgassing than the silicones, though they had different chemicals offgassing. At two weeks Alex was still clearly offgassing (at three weeks I could still pick up the odor, at 5 weeks it was very mild), and Dynoflex was close to done at two weeks.
Silicone – While silicone itself is not toxic, the chemicals added to keep caulking in liquid form are. For silicone caulk, look for 100% silicone. There are different types listed below that offgas different chemicals. Once they are cured, you may find them to be essentially the same.
The chemical additives in “100% silicone” are not usually listed. Silicone doesn’t usually have a solvent but some have traces of benzene and toluene (source). Plasticizers are typically added. The biocide, if it has one, is likely to be phenoxarsine oxide, according to Pharos.
Acoustical Caulk – this non-hardening sealant prevents sound leakage. They are mostly water-based acrylic. They are about 20% ethenylbenzene. In smaller amounts, they typically contain plasticizers, naphtha (as the solvent), ethylene glycol, and formaldehyde.
Polyether – specialty silicone replacement caulks are often polyether. My top pick is AFM Caulk.
Solvents common in caulking (of all types) include acetone, methyl ethyl acetone, toluene, xylene, and naphtha (Source).
Types of silicone caulk and what chemicals they offgas:
1. Typical silicone caulking is acetoxy silicone and it offgasses acetic acid. On the SDS you will see “odor: acetic acid”.
2. Neutral cure silicone, also called RTV, a less common type, is a lot more tolerable when wet. Look for oxine cure or alkoxy cure which offgas alcohols or methyl ethyl ketoxime.
3. Aquarium caulk is usually acetoxy silicone without mildewcide. It might be labeled aquarium caulk or you can just get GE 1 if you are avoiding mildewcide, which will be less expensive.
4. Paintable silicone caulk is a mix of silicone and acrylic latex.
Construction adhesives are used for subfloors, to install doors (glue down threshold), to build stairs, exterior brickwork, under countertops, and more.
Non-Toxic, Low-VOC Construction Adhesives
Almighty is the best adhesive I have ever tested. I had absolutely no problem and no reaction to smelling it while it was wet.
This was a pleasant surprise after all the other glues and silicones.
It is a highly tolerable very low odor, multipurpose adhesive (make sure it’s right for your application). The PSI is 500.
It is a polyether (30-80%) and nepheline syenite (30-60%) adhesive, with 1-5% amino silane.
I used Almighty to install my shower, on subfloors, and my countertops. I would use this anywhere and everywhere this can be used since it’s the healthiest adhesive I have found.
Insider tip, this is the same formula as Build Secure by Chemlink.
Wall Secure is made for bonding drywall, gypsum, landscape blocks, capstones, stone, foam, fiberglass, FRP panels, and ceiling systems.
I haven’t tested this one but this brand makes great low toxin adhesives.
3. Chemlink M-1
M-1 can perform as both an adhesive and a sealant.
It adheres to a wide range of construction materials including PVC, EPDM, most metals, wood, glass, masonry concrete, fiberglass, and solvent-sensitive foams so it works in almost any situation requiring a sealant.
With a 400 psi and 525% elongation, it also performs as a structural adhesive.
M-1 is a solvent-free silane-modified polyether.
4. Ecotite ET 5500 and 9500
This is another good brand that is well-liked by the chemically sensitive.
Their ET 5500 is an adhesive that works on multiple surfaces: PVC, concrete, glass, aluminum, painted surfaces, wood plywood, marble, metal, and more.
At about one week most would find this odorless. At two weeks it seemed totally offgassed. I was very happy with this one.
The 9500 is used for windows, doors, trim and some kitchen applications. At three weeks it’s still not odorless/offgassed. I’m not as happy with this one as it did not stop offgassing by three weeks.
The bottles say odorless, but the point in time that it is odorless depends on the conditions (curing rate) and how sensitive your sense of smell is.
Right off the bat, the 5500 is significantly milder, and lower odor than conventional adhesives.
Corinne Segura is a Building Biologist Practitioner with 6 years of experience helping folks create healthy homes.
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