The most common type of engineered wood is a flooring with a real wood layer on top and an engineered wood layer as the base.
There are three types of construction and two main finishes to consider when choosing this type of non-toxic engineered wood floor.
When looking for a zero-VOC, healthy engineered wood floor, the most important part is the construction type, so let’s start there then go on to the finishes.
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Three Types of Engineered Hardwood Flooring
1. Plywood Construction
The most common type of engineered hardwood floor has a plywood base.
The core is made of plywood and a top layer of real wood is glued on. The real wood top layer can range in thickness from 1mm up to 6mm.
The plywood which is made with phenol-formaldehyde adhesive is done offgassing by the time makes it way to the flooring company and then to you.
In general this type of engineered wood flooring is safe for almost everyone including most people with chemical sensitivities.
Some who are extremely sensitive may notice that this type of flooring can have a little bit higher odor than say a solid hardwood floor.
This is mostly due to the odor of the pine/spruce/fir used to make the plywood, but it’s possible there are some slight remnants of the glues that those who are extremely sensitive can pick up (since wood is so porous).
While the vast majority of brands have a pine/spruce/fir plywood core, Cali Bamboo Meritage line uses layers of acacia and eucalyptus woods as the core for the ply. I do think this has a milder odor than spruce/pine/fir myself. I would encourage you to get samples of both types if you are sensitive to the natural odorants of wood.
This is usually the type to choose for those wanting a non-toxic hardwood floor and for most people with sensitivities. Those who are extremely sensitive might want to look at the second construction type which has less glue.
The brands can claim zero-VOC on this type of construction.
Example Brands:
- Cali Bamboo Meritage – Oak $9.99 / sqft
- Shaw Castlewood – Hickory $8.65 /sqft
- Shaw Camden Hills – Hickory $6.89 /sqft
- Johnson Hardwood Vineyard – Hickory $6.05 /sqft
- Anderson Imperial – Pecan $5.99 /sqft
- Johnson Hardwood Toscana – Hickory $5.95 /sqft
- Johnson Hardwood Toscana – Walnut $5.95 /sqft
- Western Skies European Oak $5.70 /sqft
- Mannington Park City – Oak $5.55 /sqft
- Smokey Mountain Engineered – Oak $5.29 /sqft
- Pioneer Engineered – Oak $5.29 /sqft
- Western Skies Engineered – Maple $5.09 /sqft
- Shaw Albright – Oak $4.09 /sqft
- Shoreline Engineered – Birch $3.60 /sqft
- Johnson Hardwood Wilderness – Birch $2.65 /sqft
This video shows the different types of engineered wood, and compares them to the other wood look options:
2. SPF Quarter Sawn Construction
A far less common construction type has a core of quarter-sawn spruce, pine and/or fir (SPF) softwood wood species.
The wood is cut and laid in “pickets” (i.e. it’s strips of solid wood) which run perpendicular to the solid hardwood top layer.
While the hardwood top layer is still of course glued on, and there might be a stabilizing layer below the quarter sawn layer, there are no glues within the main core layer.
This core can also be called “solid cross slat core”. Technically this is also a ply of three layers but it’s distinct from the usual plywoods which have thinner layers (and usually more layers).
For those extremely sensitive to the natural odorants of wood or the glues used in plywood, you might prefer this type.
For most people, it’s not necessary to track this type down and I would choose plywood construction in most cases (for availability and price and because it’s zero VOC as well). But for those wanting to go the extra mile, this is definitely one to get a sample of.
These brands should not have any offgassing and this type of construction should be formaldehyde-free (or more accurately no added formaldehyde in any of the components, since wood naturally contains some formaldehyde).
Tesoro uses pine in the middle solid layer, and a thin layer of ash as the stabilizing layer below.
Example Brands:
- Mirage Hardwood Trubalance $6 – $8.50 / sq ft for most species
- Tesoro Coastal Lowlands – White Oak, Hickory, Maple, Walnut $8.87 / sq ft
- Tesoro Great Northern Woods starting at around $7 / sq ft
- Tesoro Great Southern Woods starting at around $7 / sq ft
3. HDF Core Construction
The last type of engineered wood flooring has the same top level of real hardwood but in this case, it’s glued to an HDF (high density fiberboard) core.
HDF is wood fiber that is glued and pressed together with formaldehyde. It’s more commonly seen as the core of laminate flooring.
My post on laminate flooring goes much more into detail on the chemicals and offgassing of HDF. It’s possible that some floors are made with MDF which is very similar.
The main adhesive used here is formaldehyde – the odor is very noticeable to me, though it should be able to reach Greenguard Gold levels.
For this reason, this type is my least favorite type of engineered wood flooring and I don’t see any good reason to choose an engineered flooring that has some offgassing when we have better lower VOC options.
(You also see HDF as the core of Marmoleum Click and many cork floors).
The difference between laminate floors and engineered wood with an HDF core is that laminate does not have a top layer of real solid hardwood, just a printed image, and a melamine protective coating.
You can see the difference between the two in this picture:
Example Brands:
- Mirage Lock HDF floors from Mirage Hardwood
- Shaw has some lines with an HDF core
- Some Home Depot Malibu Planks have an HDF core
- Tesoro Longevity Collection
- Valinge Engineered wood (advertised as 100% real wood, when it has a HDF (or MDF) core. Also advertised as formaldehyde-free though the HDF core is made with lots of glue.)
Two Types of Finishes on Engineered Wood Flooring
1. UV-Cured Polyurethane
The vast majority of engineered hardwood floors have a water-based UV-cured polyurethane finish with aluminum oxide.
Sometimes it’s simply listed as “aluminum oxide” or just as “UV cured finish”.
Example Brands:
Almost every brand, far too many to list!
A similar finish is a water-based polyurethane (or polyurethane/acrylic mix) without aluminum oxide. These are not as durable as an aluminum oxide finished floor but they can be more natural-looking.
The aluminum oxide is not a health concern when in solid form embedded in the floor’s finishes. This finish is so durable it won’t usually show wear for decades. Though I do consider this a risk when (or rather if) the floors are re-sanded.
Example Brand:
- Kahrs Water-based Finish Engineered Floors
2. Oil Based Finish
A few brands have an oil-based finish on the wood. They often don’t say which brand of oil-based finish they have used.
A few do say that it is WOCA, I have seen some list the finish as UV cured oil-based – which isn’t a specific brand, but the UV curing does speed up offgassing.
Kahrs and a few other brands list their oil finish as natural and/or zero-VOC.
I definitely can pick up the odor off of Kahrs oil-finished floors whereas I cannot pick up any odor essentially off of polyurethane finishes.
Though keep in mind with the natural oil you do also smell more of the natural wood odor coming through (along with the oil itself), since the aluminum oxide blocks some of the wood odor. The Kahrs oil-finished planks have a very natural look and feel to them whereas Cali Bamboo Odyssey oil finish looked and felt like a UV cured polyurethane with aluminum oxide. They say it needs an oil refresher as well.
This is also another way to avoid aluminum oxide, if you wish to avoid that.
Kahrs maintenance oil which looks to be all paraffin (kerosene), may not be tolerated though, so you do need to test out all of the maintenance products.
Rubio Monocoat maintenance oil is linseed based so should be used over linseed oil finishes or to transition to linseed oil.
Example Brands:
- Kahrs Oil Finished Line
- Tesoro Brushed Patina Collection
- Cali Bamboo Odyssey Hardwood Flooring
- Pioneer Engineered Oak
Other Additives to Consider in Engineered Flooring – Antimicrobials
Titanium Dioxide
At least one brand, Lauzon, uses titanium dioxide as opposed to aluminum oxide in the topcoat finish.
The idea here is that the titanium dioxide reacts with UV light and a PCO process occurs, which creates OH molecules that can break down germs, VOCs, mold ect.
Sometimes this topcoat is labeled as air cleaning and sometimes as an antimicrobial finish.
Other
Possible antimicrobial additives in engineered wood floor coatings:
- Titanium dioxide (nano) (Nano-TiO2)
- Silver nanoparticle-loaded hydroxyl zirconium sodium phosphate (Ag-HZDP)
- Silver nanoparticle-loaded zeolite (Ag-Z)
- Far infrared ceramic nanoparticles (FICN)
- Zinc oxide nanoparticles (Nano-ZnO)
Companies using unspecified antimicrobial agents in the floor finish include:
- Mirage
- Breezewood floors
- Goodfellow
- Many more, I will add to the list when I come across them
Other Types of Engineered Wood Floor to Consider
1. Hybrid Flooring
A hybrid flooring is a relatively new type of click-together wood flooring.
Like all engineered wood, it does have a real hardwood layer on top. In this case, it’s quite thin.
The core of the boards are not wood-based – they are a SPC – stone/polymer (PVC) composite. This is the same SPC core that you find in luxury vinyl plank (LVP) floors.
I like this type of flooring if you want something waterproof, you want to cut down on plasticizers used in luxury vinyl by having a real wood top layer, and/or you want to cut down on the amount of wood in the floor.
(Here is a quick visual post showing how to identify engineered wood, versus laminates, vinyl, and hybrid planks).
Brands include:
- Geowood by Cali Bamboo – Starting at $5.79 /sq ft
- Tesoro Lakewood Composite – Starting at $7.60/ sq ft
- Shaw Floorté Waterproof Hardwood – around $9.59 / sq ft
- Opti-Wood from Home Depot – $3.39 – 4.09 / sq ft
- Raintree – $5.50 – 6.50 /sq ft
- AquarGuard from Floor&Decor – $4.69 / sq ft
2. Engineered Bamboo Flooring
Solid bamboo or solid strand bamboo flooring is a type of engineered wood. Though bamboo is technically a grass it’s similar enough to wood flooring.
A solid strand bamboo floor has various strands of bamboo glued together. Sometimes it seems like it is a regular wood glue odor (similar to Titebond) and other times it seems like a different type of glue, maybe polyurethane.
Engineered bamboo is a flooring that has a top layer of bamboo over a plywood or HDF core.
The topcoat is a UV cured polyurethane or UV cured acrylic urethane.
Brands:
- Ecofusion Solid Strand
- Home Decorators Collection Solid Bamboo Flooring
- Tesoro Solid Bamboo
- Tesoro Engineered Bamboo
3. Eucalyptus Flooring
Cali Bamboo Eucalyptus is strands of eucalyptus pressed together with a lot of pressure and heat in a wavy pattern. I pick up the regular wood glue smell but nothing that is different from all other engineered wood.
Tesoro also makes a solid strand eucalyptus floor.
A similar product is Tesoro densified popular wood flooring.
4. Engineered Hemp Flooring
HempWood is a new type of flooring that uses hemp strands pressed and glued together as the top layer of the engineered floor. The base layer is the typical plywood construction.
The hemp layer is pressed together with a soy glue adhesive, possibly similar to the soy adhesive used in PureBond plywood. It did have a very noticeable glue odor to me which was very similar to Purebond.
They claim that there are no added VOCs and no added formaldehyde.
One sample came finished with what looked like the typical water-based UV cured polyurethane (or polyacrylic) coating and the second sample was unfinished.
Installation of Engineered Wood
There are four main ways to install engineered wood.
- Floating Floor – in this method the planks are clicked together and installed over an underlayment but not glued or nailed down. Tongue and groove glue is ofen used on the edges (Roberts is zero-VOC). This installation is good in that it is low toxicity, but the downside is that you usually can’t re-sand your floors.
- Nail Down – in a nail down installation an underlayment is used and the floor is not glued down. This is my preferred installation method over wood subfloors.
- Glue Assist – this installation involves gluing down and nailing the floor. This is often used for wide planks and/or when there are big fluctuations in humidity. If you want to avoid glue, don’t go for wide planks. Glues can be silane modified polyether or polyurethane. Silane modified is lower toxicity, but be sure to check the warranty for the floor.
- Glue Down – in this method, the glue is installed evenly on the floor. Many of the glues are polyuerethane. Some are 0-VOC like Bostik Greenforce. This method is often used over concrete. I would not use this method (and never on concrete personally, since concrete is always trying to dry upwards).
Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.
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Peter says
Ηi Corrine
I’m in Canada more specific in the province of Quebec
Have you come across any engineered wood flooring or bamboo engineered brand that is non toxic
Not much available online as far as a guide
Thank you
Peter
Peter says
I also came across bamboo engineered and their geo wood flooring at a local company in Montreal, Quebec Canada Geowood and the Opti-Wood is also available at Home Depot Canada. I just want to make a healthy non toxic choice for my two babies that have sensitivities. You are a great resource and thank you for your help from Canada
Corinne says
Yep, this list of what to look for will apply to brands in Canada and many of these brands on the list are also available in Canada.
Cherie T says
Your posts are SO helpful! Is it safe then if they have the titanium dioxide then instead of the aluminum dioxide as an antimicrobial? Is the titanium toxic? You list it out in this post but I don’t see your view on its toxicity level..
Corinne says
Titanium dioxide has a better safety profile than alumminu. But the aluminum makes it very very tough. It will be a decade before it wears down.
Ruth says
Hello Corinne, I have Kahrs engineered floors installed a couple of weeks ago. I chose Kahrs because according to their ads, their floors are non toxic. The wood floors were installed throughout the house except in the kitchen. I can.not stay in my house fior a long period of time because I have difficulty breathing, I get a headache, nausea and stomach upset. I know I wasted money by installing a new engineered floors. Are there any non toxic sealant I can use to seal the wood floors? – thank you in advance for your reply. – Ruth
Corinne says
It depends on if it’s water based finish or oil based Kahrs finish and how you want it to look after sealing. check out the posts on sealing in offgassing and sealing in the odors of wood.
Allison Rachel says
Hey Corrine,
My husband and I recently came across a European engineered hardwood brand called Muller Graff: https://www.mullergraff.net .
We like the price-point and they have many beautiful colors – though we have not found much online about the product safety online.
Have you heard of this brand? Are the formaldehyde levels essentially non-existent / safe? Does it seem legit? Sounds too good to be true, Help!
Thank you!
Corinne says
there aren’t that many differences between brands, all brands can be compared to the things to look for outlined in this post.
Allison says
So you would not be skeptical of the brands’ ‘newness’? Credibility for truthful marketing/reputation built over time is comforting.
Mitchell Shankman says
Hi Corrine! We have been looking at Mohawk Engineered Wood sold through Costco and it appears to have an HDF core. Mohawk’s website says that they use a Formaldehyde free composite called PureBond Engineered Wood Composite (Soy based).
Does that make these products any safer?
Their laminate seem to have the same HDF core with Purebond. Curious if either option seem like a safe choice to you.
Let me know your thoughts! Thank you!
Corinne says
Interesting, I have not seen that yet. Is this is what it looks like? https://www.columbiaforestproducts.com/product/classic-core/
Mitchell says
Thanks! The flooring looks just like pics above the HDF Core section of your post. Here is the Mohawk page that I found where it says all of their composite is bonded with PureBond (made byColumbia Forest).
https://www.mohawkflooring.com/wood/our-technologies/purebond
Thank you!
Mitchell says
Thanks! The construction looks similar to the HDF core pictures that you shared in the post above.
Here is the Mohawk website that discusses how they use PureBond Tech (made by Columbia Forest) in all engineered wood products: https://www.mohawkflooring.com/wood/our-technologies/purebond
Let me know what you think!
Corinne says
Thank you. I saw that page but then browse products went nowhere. From that page it looks like they are not using the soy based Purebond but phenol formaldehyde-based (instead of UF-based). It looks like purebond has two types of this product, the other is MDI based. I’m not a fan of MDI. But I will need to contact both companies to figure out what is going on here.
Corinne says
I reached out to Mohawk and they said “Mohawk no longer uses Purebond for any of our engineered wood products.”
Maribel says
Hi!
Do you have a post or resource that has a recommendation for what underlayment to use under engineered wood over slab, so as not to support a mold environment if the climate is humid?
Corinne says
There is a post on underlayments that goes over the options
NZ says
Is engendered wood installed over tile okay? Floatubf or glued
Corinne says
Yes usually you can put engineered wood over tile. Talk to your contractor.
Lauren says
Corinne, thank you so much for all of the in depth information you share! I’m curious is Shaws LVP is reliable across the board or just with the 2 samples you listed?. I know they’re made with virgin product and have had my contractor reach out to see if their plasticizers are bio based. Wondering if there’s anything I should Look out for? Thanks for your time
Corinne says
https://www.mychemicalfreehouse.net/2021/07/choosing-a-non-toxic-vinyl-plank-floor.html
Grace says
I am multiple chemical sensitive with heart surgery, brain injury, reynauds, venous insufficiency, can not take pharmaceuticals. Inflammation problem. I told flooring company no toxins. I was ignorant. Every thing they used was toxic. Padding old, ripped, brown, toxic glue. The carpet polyester. We couldn’t breathe. I’m 74. My husband 82 with rare biliary disease and transplant recipient 30 years ago. We have been very sick and sleeping outside bedroom. What brand of flooring and installation do you recommend over concrete in the low country of South Carolina.
Corinne says
Hi, the main flooring post is the best overview of your options. https://www.mychemicalfreehouse.net/2021/04/zero-voc-flooring.html I prefer breathable flooring options over a concrete slab in most cases.
Deb says
I really think your guidance on this blog is helpful! Thank you so much.
We had a kitchen flood on our main floor in sunny Southern California and now have to replace all main level flooring. The foundation here is a slab. We would be interested to use engineered hardwood however I think you pose some concerns about moisture when using this with a vapor barrier over a slab. Is there a work around? Would that be a big concern on a main floor in a sunny climate and/or are you just concerned about that in basements?
Regarding other options, I am concerned about using tiles because of the tile cutting in our front yard/lead dust.
In looking at other options, I can’t find concrete tiles for large areas, they all seem to be designer decorative for small areas.
thanks in advance for any tips you can offer! Really love this site
-Deb
Linda says
Can you advise how & where to get current 2021 technical info: MSDS and manufacturing technical info on Engineered flooring made by Samling Global?
Corinne says
Ask them for it.
Linda Cullen says
Hi Corinne,
Thanks again for your help. I have read your information on flooring. The flooring options in my new under construction production built house are very limited. Carpet, vinyl, or laminate. The brands are limited as well. I chose laminate. I don’t have the money to afford a custom built home and am too old to fix up an old home. My question regards checking for and, if possible, taking steps after construction to minimize the chance of mold under the cement slab and above the moisture barrier. Any advice is appreciated.
Thanks,
Linda
Vikram Malhotra says
You say glue down should not be the installation over concrete? Would you then suggest floating floors for engineered hardwood? Wouldn’t that compromise the feel of walking on hardwood?
Karen says
Wow! You seem to know so much about chemicals… My daughter is looking at colleges an wants to know what kind of degree you have?
Corinne says
My qualifications are on the about me page and on my linkedin https://www.mychemicalfreehouse.net/blog-page_24 If someone young wanted to go into this a degree in chemistry would be the way to go. Alternatively a masters in architecture or masters in building science.
Danny K says
What do you think about Kahrs engineered wood? It seems that their stuff is quarter sawn, and they release their test results, which seems to be a good sign! But as far as the toxicity of their products, do you have an opinion? I have seen that Green Building Supply recommends Kahrs.
Corinne says
I mention Kahrs in the post in a couple of categories. None of their floors that I have seen have the quarter sawn base, they have the ply base.
Danny K says
Okay, thank you!
Carla Romano says
Hi
Thank you for your info. Our priority is a toxic free floor. We are looking at white oak engineered by Riva Max. What do you think of this? It says calm compliant and zero emissions but I don’t see anywhere where it says VOC free. Any help you;d be hugely appreciated
Carla
Corinne says
Hi use the post as a guide to what to ask them about it.
Janet Cook says
Thanks for your intelligence and wonderful work. I have three questions.
1) Is there a place you discuss non-toxic (or less toxic) floor glue?
2) Can you suggest some Engineered wood that can SOME waterproofing or pet protections?
3) Place where I can send you a donation?
Gay says
If the engineered flooring is Green Guard Gold certified do you need to worry about the finishes, stains, glues etc or anything else about it.? We are looking at redoing flooring in bedrooms and considering
Kentwood does not use aluminum oxide but does 8 layers of Polyurethane finish. 35 year wear thru warranty.
Corinne says
Yes I would still follow the guidelines in this article and get the ply or solid slat base.
Tamilyn says
Love you information thank you….I have read the above numerous times and still can not understand if Cali Geowood is non toxic or not? I have a lung problem and sensitivies is the Geowood good or would Anorim Cork Wood line be better?
Corinne says
It’s up to you on what you consider toxic. Geowood contains plasticizers. Amorim cork is higher in offgassing than I would like but technically it is very low. You should test for your own sensitivities.
Julie Freeman says
Do you have an opinion on Mannington Restoration laminate flooring line? Ok, good, bad?
Nolla says
Ty, this is great info! So glad I found your site:) I have engineered hardwood and trying to find an eco cleaner cleaner beyond Bona – which is very popular. Do you know of any brand or diy to clean this type of flooring??
Corinne says
For a water based finish I just use diluted dish soap.
Jenna says
Hey Corrine, could you tell me what the sample is pictured in the bottom middle under the 1. UV-Cured Polyurethane heading?
Corinne says
It might be from Mirage.
Sanya says
Love it, Great info!!! Currently looking for new flooring and overwhelmed… in addition I need all kitchen and bathroom cabinets painted. Do you know of any non toxic low voc cabinets primers and paints please? Thanks a million!!!!!
Corinne says
It’s often sent out to be professionally done but in the paint post there are some options there https://www.mychemicalfreehouse.net/2020/06/non-toxic-zero-voc-paint.html
BELIZ Iristay says
Wonderful post!
Thank you.