There are a variety of underlayments used under wood floors, click-together floating floors, as well as carpet and tile.
Underlay can serve various functions like cushioning, sound deadening, leveling, uncoupling, and moisture resistance.
The following underlayments are relatively high in offgassing (too high for me):
- Polyurethane foam
- Rubber (most SBR rubber)
- Vinyl (like Mass Loaded Vinyl)
- Most cork underlayments, except the ones listed here
This post goes over the best non-toxic low-VOC options.
This article contains affiliate links, upon purchase I make a small commission at no extra cost to you.
Paper Underlayments Used Under Wood Floors
Silicone Paper
Silicone paper is usually used under real solid hardwood floors, but it can also be used under engineered wood. It is semi-permeable which is good, as you want your upper floors (over wood subfloors) to be breathable in almost all situations.
It meets perm ratings recommended by the National Wood Flooring Association.
Those extremely sensitive to chemicals have liked this product a lot. If you just need something simple that is not providing sound dampening or leveling this will do the job.
Red Rosin Paper
Tried a true, Red Rosin is the old school underlayment paper used under real wood flooring. It’s extremely low in odor and even that dissipates rather quickly. The extremely sensitive almost always do well with this, with only a few people mentioning that the undyed Rosin Paper was preferred.
This is what I would use under wood floors. Keep it simple and breathable.
Foam Underlayments for Click Together Floors
Basic Polyethylene Foam
For laminate, engineered, and other click-together floating floors I prefer the most basic polyethylene underlayment. It’s very simple – it’s one of the safest plastics in terms of odors and offgassing (it’s zero-VOC).
This provides some cushioning which is necessary under flooring types like laminate.
It’s not a complete vapor barrier (if it doesn’t have an attached polyethylene layer), so it can breathe, which is great for upper-level floors. Plus, it’s very inexpensive.
This is the type of foam that comes pre-attached in some laminate lines. I find that very convenient.
A “2 in 1” will usually have polyethylene foam and a thin layer of plastic. If you are looking for a vapor barrier, make sure it has one attached. The term 2 in 1 is rather confusing in this sense, as some are moisture-resistant and some have vapor barriers, but they are very thin.
Check with the flooring company and your contractor to make sure you have an appropriate vapor barrier, if one is required.
Cali Bamboo brand makes a good polyethylene underlay with foil as the vapor barrier, made for their floating floors. Antimicrobials are not listed in the description.
And Kahrs makes a polystyrene foam with 3 mil poly plastic for their engineered floors. They do mention it has mold-reducing properties so it might have an antimicrobial.
Some are just the foam, which is the type I would use over wood subfloor.
Polypropylene Foam
Polypropylene foam is another very safe plastic. It’s not as breathable as polyethylene and I have only seen it advertised as being a vapor barrier or as having a vapor barrier (another plastic layer) attached to it.
It’s used for laminate, LVP an and engineered wood (mostly) when a vapor barrier is required. It can be used under solid hardwood floors to provide cushioning and sound dampening.
If it’s labeled 3 in 1 like this Traffic Master opion, which usually means it’s cushioning, sound dampening, and a vapor barrier.
Floor Muffler has not tested their products with carpet. Their polypropylene underlayment is free of any added flame retardants they do list antimicrobials in the description.
They have a high acoustical rating, the one below can meet IIC up to (74) dB per ASTM E 492 / ASTM E 989, STC up to (73) dB per ASTM E 90. Mohawk Silent Guard is STC 73, IIC 71.
EVA Foam
EVA foam is another safe foam. Compared to polypropylene and polyethylene it does have slightly more of an odor.
EVA foam underlayment can be used under floating floors like engineered wood, laminate, bamboo, and vinyl as well as carpet. (Also at Home Depot). Antimicrobials are not listed in the description.
IIC (Impact Sound Transmission Test) rating is 73, STC (Sound Transmission Class) is 72.
Felt Underlayment For Engineered Floors
Felt + Vapour Barrier
Quietwalk is felt and a vapor barrier made for under laminate and engineered wood as well as other floating floors like bamboo and luxury vinyl plank.
The felt and (polyethylene) plastic layers are quite safe even for the chemically sensitive. It claims to be zero-VOC.
This one does contain Microban (Microban can refer to 6 chemicals, so this could be anything from silver to something more synthetic). If you want it without antimicrobials, you can get Quietwalk from Green Building Supply.
Because this has a vapor barrier it’s meant for on top of a slab or basement floor. If you do lay down laminate, engineered, or another organic-based click-together floor on a slab or basement you do need a vapor barrier.
Best practice, according to mold preventative architects, is not to apply flooring that requires a vapor barrier over a slab because a concrete floor is always trying to dry to the inside. As a mold-sensitive person, I can smell the mold that festers underneath when a vapor barrier is applied. And it happens in most homes in my experience.
Available on Amazon, Home Depot, and Walmart.
Natural Material Underlayment For Many Floor Types
Breathable Cork
Cork underlayment is one of the most expensive underlayments. It provides good cushioning and sound dampening as well as some leveling.
It can be used under engineered hardwood, laminate floors, hardwood flooring, and ceramic tiles.
It’s possible to use Thermacork under some flooring types if that is designed into your system. It’s very thick. But it’s 100% natural (it’s just cork heat pressed together).
But if you’re looking for an underlayment type of cork, the small pieces of cork are usually pressed together with a polyurethane glue which I find to be quite strong in offgassing, so I don’t personally use this underlayment.
However, some brands are made with polyethylene as the binder, which is much much better in terms of odor and offgassing. Eco Cork Foam, says they use polyethylene as the main binder.
Like many underlayments, it does contain an undisclosed antimicrobial would could be problematic.
They also recommended gluing the underlayment down.
There are many flooring types and brands that come with an already attached cork underlayment, which also always has this polyurethane offgassing odor.
1/2”(12mm) cork underlayment has STC 49 and IIC 48 sound ratings.
Pressed Wood Underlayment
This Steico product is a lot more unusual than the others. This is different from the old particle board underlayments. They claim it is more water-resistant than particleboard.
It’s a pressed wood product, but they don’t mention what kind of wax, oil, or glue is used to make it. They do claim it is zero-VOC and 100% natural.
It can be used under floating floors like LVT, laminate, and engineered wood, as well as hardwood floors.
It seems to be very good at sound dampening.
Available on Amazon or Walmart.
Vapor Barrier for Over a Slab or Basement Floor
6 Mil Poly
This is the most common vapor barrier for slabs and basements. If I was going to put down a vapor barrier (which I wouldn’t due to the reasons discussed above) I would go with plain 6 mil polyethylene plastic. There is no need for anything fancy here. Though it does not provide cushioning. If cushioning is required it makes sense to buy a foam and vapor barrier in one. I would make sure it’s 6 mil though.
Flooring with Attached Underlayment
Many click-together floors come with an attached underlayment. This really helps in simplifying things.
I like laminate floors with polyethylene foam backing attached, LVP with rubber or foam underlayment attached.
Some LVP comes with an EVA underlayment.
Luxury Vinyl Plank (LVP) with a cork backing does not make sense to me in a basement, slab, or wet area since one of the main benefits of LVP is that it is waterproof and very mold-resistant. Cork underlayments also tend to have more offgassing.
Underlayment for Tile
I like the Schluter system under tile.
If you need zero-VOC acoustical control under tile Schluter DITRA-HEAT-DUO providers a ΔIIC contribution of 20. Cork underlayment can also be used under tile.
Schulter has different membranes that I discuss more in the grout and thin-set post. They are made of a non-toxic very low odor plastic that even chemically sensitive folks do well with.
Many acoustical underlayments for tiles are rubber or vinyl-based, and I would personally avoid those as they are one of the highest offgassing products in a home. (Whisper mat is one that is mostly foam with some asphalt adhesive, so that would be an improvement over most rubber underlays).
Laticrete Fracture Ban is not toxin-free but it’s one I have seen that the company says is breathable. LL Floors Fiber Fusion Anti-Fracture Crack Isolation Membrane is also breathable, according to the company.
Photo Schulter membrane from Amazon.
You can also find Schulter products at Home Depot.
Underlayment for Carpet
The main healthy options are natural wool felt for wool carpet, polyethylene, EVA foam, low-odor synthetic rubber, or built-in synthetic felt.
My carpet post goes into detail on underlayment for carpet.
Corinne Segura holds certificates in Building Biology, Healthier Materials and Sustainable Buildings, and more. She has 10 years of experience helping others create healthy homes.
If you would like to support the research behind this blog you can make a donation via Kofi!
CJ
Hi Corinne, thank you for all your tips !
I’m a little confused .. i just purchased a 1950s house that is very well build with thick slab but we had to re-do some plumbing (old pipes got rusty) and thus jack hammer up some slab. The slab that was originally built had a thick layer of epoxy (like 1/8th of an inch) and the studs on that we removed show no signs of mold.
What should I do when we patch up the slab ? Leave it ‘raw’ ‘unsealed’? or paint it with something like drylock ? We will be placing back the stud frame on top of this slab. And then the rest of the floor will be tiled with porcelain tile.
Since this house has a big fat foundation and a thick slab and cinderblock walls is the slab not able to dry from the outside ? Leaving me able to seal up the slab with a layer ?
Is there an in-between product ? like a breathable system ?
What about buying a large hunk of beeswax to seal the slab . would that breathe ?
I’m asking because I’ve been sick from mold for 3 years from rentals prior to buying this house … and I am trying to get this done right.
Cheers
Corinne Segura, Building Biologist
you will need some building science advice there. its unusal for a thick slab to have an epoxy coating and if that was put down becase lots of moisture was drying up then you will need to keep that in mind. the slab can only dry inwards, it cannot dry down or to the sides. its best to keep it breathable, see video by me and cheryl ciecko on my youtube channel but the next best option according to cheryl is to seal it with a liquid coating like epoxy
craig
I was wondering about the Eco Cork Foam underlayment, I was about to purchase it when I saw a comment about the Microban in the cork. In the product description i see “Ultra-Fresh® antimicrobial technology is infused into Eco Cork Foam for an added level of product protection against stain and odor causing mold and mildew.” Ultra-fresh is Microban, which has EDCs. Whats the deal with that, is it gonna effect me underneath my floor? And why is it on My Chemical-Free House site
Corinne Segura, Building Biologist
We don’t know what chemical/chemicals UltraFresh is. It’s not disclosed at all. Some of Microban’s antimicrobials are disclosed and their most popular one silver is not usually a concern for chemically sensitive folks. Others could be a concern even though they are blocked by the floor because they could offgas, depending on the chemical. but I have updated the article as that either wasn’t listed in 2020 or I missed it.
Patricia G
Hello,
I bought a condo and want to replace the 90’s dusty carpet with engineered hardwood. This is a concrete condo on the 8th floor, with electric baseboard heat. The contractor recommended Mirage flooring and I have some samples on order (maple and oak to try, with plywood core). For underpad, he recommended Good Neighbour Silencer XP 3.0. Becasue it is a condo, I can only replace carpet with hardwood if I use sound dampening underpad. This product is made of High-density IXPE foam and has vapour barrier and is antimicrobial. I am in the process of trying to find out what the antimicrobial substance is and obtaining a sample, but does this product seem like a good idea? I am extremely mould sensitive and live in the Pacific Northwest (Vancouver, Canada). I am also quite chemically sensitive due to a viral infection from 2020 which gave me emphysema, MCAS plus several new IgE allergies (dust mite, cladosporium, lanolin, limonene, linalool, etc). I am wary of generic “antimicrobial” due to horrible experiences with a product called Benefact.
https://goodneighbourunderlayment.com/product-details/silencer-xp-3-0/
Corinne Segura
IXPE should be fine, not likely any offgassing there. As for the antimicrobial, I don’t know what they are using. You will have to go by your own assessment, it won’t be like benefect but I don’t know what they would be using.
Dee
I am also looking to install floor in an upper level condo on concrete. Are the concerns about mold for slab and basement the same for a concrete building with multiple units?
Corinne Segura, Building Biologist
no, there is no moisture coming up in an upper level concrete floor. you can use flooring types like LVP that block moisture. i would still prefer not to have two layers that block moisure so that if water spills it doesnt get stuck between two layers
Dee
Thanks Corinne! So your preference is still for something vapor permeable, meaning no engineered wood, laminate or vinyl flooring? What about microcement instead of the insane expense of tiling or concrete polishing?
Corinne Segura, Building Biologist
you can use any flooring type, but i would prefer not to have both the floor and the underlayment and moisture blocking layer
Kat
I have mast cell activation syndrome and multiple chemical sensitivity . I am purchasing an older manufactured home (particle board subfloor) and we will be replacing all the floors. The crawl space has a vapor barrier over the dirt and a “belly wrap” above that. On the floor side of the belly wrap are the joists, insulation, and subfloor. Any idea if I need a vapor barrier as part of my underlayment? We are hoping to do a plywood floor sealed with Vermont naturals floor sealant. We will be putting this throughout the whole house , including bathrooms and kitchen. I keep reading conflicting info online about if a vapor barrier would be beneficial between the subfloor and plywood (finish floor) or not. My husband thinks we should use roofing paper but I am worried I’ll react to that. We have kids and pets if that makes a difference. Thank you, your website has been so helpful to me.
Corinne Segura
both a plastic barrier and a breathable underlayment like the ones in this post have the potential to cause moisture and mold problems so be sure to consult with Cheryl Ciekco or another building science expert.
pmfb
hi!!
we are nailing down pine boards for our bedroom flooring. the underlayment suggested was tar paper, and the flooring is already halfway down.
i did not see this option in your blog post; thoughts?
Corinne
I wouldn’t use that but I have two alternatives in the post
George C
Corrine – I am sending this link out to a bunch of people in my industry – wood flooring.
Corrine, really well done. You answer a problem three years ago that is only started in this trade article; https://hardwoodfloorsmag.com/2023/08/01/plastic-flooring-installed-on-top-of-wood/
pmfb – you are talking about 15lb asphalt-saturated felt paper. It works best BUT does have VOCs that show up in smaller areas; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435637/table/sensors-20-04099-t003/?report=objectonly (part of this study; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435637/#sec2dot3-sensors-20-04099)
Leah
We are in the same boat. Our contractor used „HWD-15“ underlays, which does seem to be certified as low emissions under California standards. I don’t see this mentioned in the post at all— have you heard of it? I really wish they had spoken to us first.
Corinne
this is the typical asphalt paper, the silicone paper and rosin paper are the better alternatives, especially for the chemically sensitive.
Jay
Hi! I came across this “Natural LVT SG” underlayment. This stuff makes some bold claims. It’s quite nice-feeling too. I got a small roll to check it out. It adds a degree of warmth, is relatively thick, and does not appear to give off any odor. What category do you think this falls under?
https:// naturalunderlayment.com/underlayments/natural-lvt-sg/
Eliza
Corinne, I’m desperate for help! We put an engineered hardwood on top of a cement subfloor with a QuietWalk barrier. I’m clearly very mold sensitive because the smell is oppressive and my allergies are on fire. I live in a pretty humid climate. What do we do? What floor can I put on cement subfloor that doesn’t require a vapor barrier? Thanks so much!
Jose Poloramos
A question regarding the sleeper system on a concrete slab. Would Rosin paper be placed over the slab, then the sleeper floor or would some other solution be better?
Corinne
you’d have to consult with a building science expert
Heather
What are your thoughts on the air gap underlayments? I’d like to put hardwood over an at/below grade concrete slab. Tile is way too cold for my climate and this is a cold room (and heated tile way too expensive), and carpet is a non-starter with my allergies (I just ripped out the carpet that was down there). I don’t do well with linoleums, laminates or LVP. I’ve seen contractors recommend some of the dimpled underlayments like Dampro or Dricore for preventing mold. Do you have any experience with them and the mold issue?
Corinne
not enough air movement under those for moisture to dry out says Cheryl ciecko.
Violetta Sur
My contractor purchased a waxed paper underlay. It doesn’t seem to smell at all but I wonder if it could possibly contain any PFAS or other chemicals, and if so would this even be a problem in a waxed underlay? It is similar to this: https://www.homedepot.ca/product/roberts-750-sq-ft-3-ft-x-250-ft-x-009-inch-waxed-paper-underlayment-for-wood-flooring/1000496301?eid=PS_GOOGLE_D23%20-%20E-Comm_GGL_Shopping_PLA_EN_Flooring_Flooring__PRODUCT_GROUP_pla-341957376360&gclid=CjwKCAjwvJyjBhApEiwAWz2nLYSgrjmjgjM39Vem9mv_QzNIXZ8m65tf2zGgd8HG0c4iLDI7UC8SvRoCUh4QAvD_BwE&gclsrc=aw.ds
What are your thoughts?
Violetta Sur
Is it generally considered a less “toxic” option for sensitive folks?
Corinne
yes
Kelley
Hi! Hemp Underlayment is challenging to get.
But i was wondering if this could work: hemp and jute canvas.
It would be going over wood, and under engineered wood (not glue down).
https://www.jerrysartarama.com/soho-urban-blanket-unprimed-no25-hemp-25oz-6yd-x-86in-86324a?gclid=CjwKCAiA-dCcBhBQEiwAeWidtQCvdE28oQ8ZbxwVGbYHwbU6xRz-mNEEggsg89o4PJwSNpAfIsF1jRoCo8QQAvD_BwE
Rene
Hi Corrine, I have a treated timber subfloor and I am trying to prevent any fumes from the subfloor entering inside the home. We are having engineered timber flooring laid over the subfloor. The glue we are using to secure the engineered timber is very good (A+ French interior air certified) European glue. This glue can also achieve a vapour barrier. If I apply it over my treated subfloor as a vapour barrier do you think this would be a good solution to prevent the subfloor offgasing inside the home? or will this cause mold issues if it is not a breathable layer between the subfloor and engineered timber? If so, is there another solution you could suggest? vapour barriers and mold is all new to me. Many thanks
Kavitha
Dear Corrine,
First of all, thank you so much for your thorough posts!! It is extremely helpful!! We have one question for you – is Aquabar safe as an underlayment? Thank you so much for sharing your advice and wisdom!
Thank you again,
Kavitha and Nicolas
Corinne
I wouldn’t use that over the options in this post
Emily
Hi! Any thoughts on COREtec’s new Soft Step underlayment, touted as being made from 100% recycled plastic bottles? I chatted with a rep on the website who said it is free of phtalates ad parabens, and the greenguard gold certification includes the underlayment. I just worry about adding more plastics.
Britney
Hi there! Do you have experience with Quietwalk Plus being used with nailed down engineered hardwood on a wood subfloor? We purchased it already to use under floating floors and have now decided to nail them down. Green Building Supply said that nail down is fine and so does the product. Just wondering why you mentioned it is best with floating floors. Thank you!
JY
Same question – Britney, what did you end up putting under the nail down floor? What floor did you pick out?
Michael
Hello there. There is so much information here. Thank you. I am wondering if you have anything to say about Absorba sound underlayment. It’s recycled rubber and I am a little wary about offgassing but flooring guy said don’t get foam because it compresses so much. Thank you for any thoughts. We are nailing the hardwood down on second floor over plywood.
Corinne
I would never use recycled rubber. See the post on Gym Flooring for details on rubber flooring.
Michael
Thanks so much Corrine. That’s awesome. We’ll shift to polypropylene.
Bri
For underlayment under a click and lock waterproof system, how much direct exposure would you really have to the antimicrobials in the underlayment? Does it leach through into the air? If you don’t have any known sensitivities to antimicrobials, how big a deal do you think they are? I’m trying to decide if the QuietWalk without the antimicrobials us worth the extra cost. (It would cost almost twice as much for the amount we need!) The regular kind It is still Green Guard Gold. Their blog lists their antimicrobial ingredient.as Polyphase 678 https://www.mpglobalproducts.com/blog/quietwalk-underlayment-includes-antimicrobial-pesticide-to-eliminate-mold-related-worries/
Corinne
Under a luxury vinyl plank floor I would say the risk is none.
Bri
Thanks for putting my mind at ease and helping me prioritize in my budget!
Julie Wilde
I am buying a 2750 s.f. concrete slab 1970s house on the east coast marsh. I am tearing out the original carpet that covers the entire interior and Ideally would like to replace it with wood flooring (or click lock engineered) for aesthetic purposes and comfort on joints as I have hip issues. I have always lived in older homes with gorgeous wood floors and can not stand comfortably on tile or carpet. I also have extreme sensitivities to chemicals and mildew. I believe that you said not to use a flooring that would require a moisture barrier on slab due to potential mold issues? If I insist on a wood (no vinyl) flooring for reasons stated above, could there be a solution for me?
Corinne
Talk to Cheryl Ciecko about building a sleeper system (which is not the common one you will see if you google it).
Julie Wilde
Thank you, Corinne. i appreciate your quick reply. I will try to contact Cheryl right away. If I can’t figure out a way to safely install wood over the concrete flooring, I may need to get out of my contract on the house a.s.a.p.! So glad I came across your article regarding moisture/mold problems in concrete flooring before it was too late!
Dianne Fradkin
Corrine,
I am desperate to find new flooring in my rental unit to replace carpeting that’s probably 20 years old.
I am very chemically sensitive and have tried bamboo and prestained hardwood, a box of each as a test, both of which I have been unable to tolerate.
After reading your article it seems tile would be best.
Which do you think would be least toxic and what underlayer would I use?
I would gladly schedule a 30 minute phone appointment but it seems that none are available for several months so I am asking for your help in this rather long email.
Thank you so much,
Dianne
Corinne
Hi Diane, I am doing email consultations if you would like to go through the options. I would also need to know what your subfloor is. https://app.acuityscheduling.com/schedule.php?owner=19257501&appointmentType=16364655
Gaye
When reading your info you recommend using a product that breathes for an underlayment on 2nd floor over wood. We are floating Engineered Hardwood over old vinyl tiles so should it still be a product that breathes? I am not wanting to trap in moisture! So I am wondering if the Robert’s Serenity polyethylene foam would be our best choice as it would provide some cushioning to dampen the clicking from a floating floor and you say it is also breathable.? Open to other suggestions that would also be good to use . Thanks. (I am not wanting anything with antimicrobials as I don’t want to be exposed to those chemicals.) ( Quietwalk from Green Building is not available in Canada right now.)
Thanks.
Corinne
Vinyl tiles are a complete vapour barrier so it doesn’t matter if your underlayment is breathable or not.
Tamilyn
I would be so grateful for any help. Im beside myself reading over and over again all of these floorings and your article. I just bought a mobile home w/crawl space lots of humidity at times. Current flooring vinyl top peeled off prob because of humidity. Which is the safer flooring for a lung condition and some water barrier protection LifeCore waterproof is only Floorscore certified best at blocking water, AquaGuard limestone engineered wood is greenguard gold, HydroShield HDW base core a Laminate is Greenguard Gold or Shaw Laminate OptiCore Board GreenGuard Gold buts also a Laminate. My only other options would be Cali Bamboo Geowood again limestone or Anorim Wise Wood. What out of all of these would be the best for lungs and health? Solid wood in humid mobile home I was told not the best, tile living off a train track also not good and I react to linoleum vinyl super bad. Can you please give me your thoughts begging please.
Akua
Hello Corrine, this post has been so interesting. I want to put LVP down on a tiled floor. No glue! I am in the UK. I want to know what the best thing to put down underneath is. Least off gassing and most resistant to mold. I live on the 8th floor of a high rise apartment block.. Thanks
Corinne
Hi Akua, I am also born on a wednesday. This post goes over the main options but also check the warranty as many have a preattached underlayment and the warranty can be voided by adding another underlayment.
Rachael Bonsignore
Hi Corrine. Have you found out anything about the possible toxicity of Iron Ply that is used under linoleum in the bathroom? It looks like a kind of thin plywood. It looks benign, but I started getting symptoms after it was installed- very loud ear ringing, chest or lung pain…Could be the wood itself I am reacting to, or something else in the house (a little bit of spray foam used recently or vinyl siding stored in house). I didn’t smell anything when I put a piece of it up to my nose, but I did smell a strong chemical smell on it after I soaked it in water for an hour or so.
Corinne
I haven’t seen that before, could you ask them what is in it?
Anne Robinson
Hi there-
Thanks so much for all this information.
We are using self-leveling concrete on our basement floor and then buying wool carpet with wool padding. Are there any concerns with self-leveling concrete?
I have looked all over the internet but have not found definitive information. The self leveling was our only option as redoing the floors entirely was beyond our budget and would have lowered the wall height. Should we air out for a long time after using the self-leveling concrete?
Corinne
Most of them are 0 VOC.
zuzana
Hi,
I bought recycled hardwood floor which I would like to lay in my basement apartment. What underlay would you recommend for the basement flat? I am confused about the vapour barier! The floor is concrete.
Many thanks,
Zuzana
Corinne
I personally would not put any type of wood over a concrete basement floor or slab on grade due to moisture. People do this, it’s the norm but mold is also the norm in buildings.
Candice
So you’re recommendation is to remove any existing plywood and use foam only underlayment, is that what I’m reading? I feel like this was vague in the blog but clarified more in comments. Thanks for the info
Corinne
You don’t usually put plywood down over concrete before installing your floor. It is done sometimes like if you want to put solid wood down but that other than that is not the norm.
Poon
Thank you so much Corrine for all the information. Would you suggest using Quietwalk plus under solid unfinished hardwood floors? Thanks.
Corinne
I would talk to your installer about that, since it’s mainly specified for floating floors.
Hawnes
Hi Corinne, thanks for the informative post.
I want to install linoleum upstairs. What would you recommend for either linoleum sheet vs. click as an underlayment?
Thanks.
Linda
Corinne,
Thank you for sharing this valuable healthy living information. You mentioned not to install flooring that requires a vapor barrier over a slab. I am having a concrete slab house built and am trying to be as green and non-toxic as possible. Mold terrifies me.
What type of floor that does not require a vapor barrier can be installed over a concrete slab? Also, is it possible to put a raised sub-floor to eliminate the need for a vapor barrier, if I can get the builder to do it?
Thank you,
Linda
Charlotte, NC
Corinne
Hi, polished concrete or tile or yes like you mention a “sleeper system” which is raised up. I would have Cheryl Ciecko detail that.
Linda
Thanks.
Tatum
Corinne,
Can you clarify doing polished concrete if you are under grade as I thought I read you recommend against sealing the slab (epoxy or other) due to ensuring it dried to the inside?
Wouldn’t polishing it prevent it from drying to the inside?
I appreciate the clarification as I’m trying to figure out our best flooring route for our finished walk-out basement. The north wall is completely under grade, while the west and east are partially under grade and the south wall is fully walk-out.
Blessings,
Tatum
Corinne
Polishing with (sodium/potassium/lithium) silicates is breathable according to the building science experts I work with.
Jonathan
Thank you so much Corinne, this is very helpful!
I called MP Global regarding Quietwalk and they said the use Polyphase 678 antimicrobial made by Troy (http://www.troycorp.com/product_view_Preservatives.asp?unitName=Preservatives&cat=products&sub=functions&ID=483) in their Quietwalk underlayment. The product info sheet (which I found doing a search since Troy requires an account) seems concerning. What are your thoughts?
Would something like FloorMuffler be a safer choice? https://www.floormuffler.com/products/floormuffler/
Thanks so much!
Corinne
Green Building Supply sells quietwalk without the antimicrobial.
Jonathan
Ahh yes, I forgot you mentioned that! Thanks!