I used to think hardwood didn’t need underlayment. Pad was just for carpet.
But this isn’t the case. Many times it’s not optional–you have to have underlayment. But even when it’s not required, there are plenty of good reasons you might want it.
Here are the goals of this article and what we’ll cover in order:
- Decide if you need underlayment for your hardwood
- Decide what underlayment you should choose
- Answer any final questions: pricing, radiant heat, etc (can leave any questions in the comments)
Is underlayment necessary for hardwood floors?
The short answer: usually.
If you already have a plywood subfloor, and the subfloor is smooth and level, then you may not need an underlayment beneath the hardwood floor. Plywood has some moisture resistance already compared to solid wood, and it mostly gives a smooth surface.
So plywood likely means you aren’t required to have underlayment, but it still can provide other benefits.
The top 5 benefits of hardwood floor underlayment
There are two reasons it helps to know why you might benefit from underlayment:
- So you can decide if you want it in cases where it’s not necessary.
- So you know what you’re paying for, and what features to look for.
What I mean by point 2 is, if you don’t know what benefits underlayment can provide, than you won’t know why you should spend more or less. Or why it even matters what underlayment you choose.
Let’s take a look at all the benefits:
1. Moisture barrier
One of the most important reasons to use underlayment is to protect your hardwood floor against moisture damage. You can often find underlayment with an added vapor barrier which helps to keep your wood floors safe from water damage.
You will often see this recommended for floating floors, but when it comes to keeping water and moisture away from your hardwood floors, every bit helps. No matter how well installed or maintained, any gap between the planks can let water seep under your floor. Once the water has soaked into the floors from beneath, you can be facing expensive damages once the boards warp or break.
Captain’s warning! You should avoid nailing through some types of waterproof underlayment, as the punctures will keep them from working correctly. Always check the underlayment warnings to see if it can be used with a nail-down installation. If not, your installer should take precautions, such as installing another plywood layer on top of the underlayment, to keep from damaging it.
2. Subfloor imperfections
An even subfloor is one of the first requirements for any hardwood flooring installation. When you nail or glue wood floor onto an uneven surface, the finished wood floor will also be uneven. Not only does this pose a tripping hazard, it also leaves your beautiful wood floor looking less than perfect.
Major flaws should always be repaired before installing hardwood floors, but minor dips and cracks do not necessarily require a complete overhaul. If you can find an underlayment thick enough to compensate for small, uneven areas, it would be less expensive and faster to use that than to tear apart the whole subfloor.
3. Noise reduction
Put simply, a busy household on wood floors can produce a lot of noise. From kids and pets running and playing in the living room to the background noise of voices, televisions, and general household ambiance, the sounds can quickly add up.
You can find underlayment that helps absorb sound from the air and keep the sound waves from bouncing quite so vigorously around the room. Other types of underlayment muffle sounds made on the floor itself, which is especially helpful for upper stories of your home if you do not want to hear every footfall from lower levels.
4. Comfort
Another drawback of wood flooring is that it’s a solid, sometimes cold, surface and not especially pleasant to walk or stand on for long periods of time. If you have chosen a harder wood floor, known for its durability and longevity, this may be even more noticeable.
So in these cases, underlayment will be an added investment that you will thank yourself for on chilled winter nights and any time you walk on areas not covered by rugs. Underlayment cushions your feet when you walk on the hardwood floor and insulates it from intense temperature change.
5. Stabilizing floating floors
If you have installed engineered hardwood as a floating floor, then underlayment will be very important. Floating floors are not attached to the subfloor so they can easily expand and contract when exposed to the moisture and heat in the air. Moisture can also pool up in the gap between the subfloor and the floating engineered hardwood, which will eventually damage or warp even the best-engineered hardwood flooring.
Best type of underlayment for hardwood
There aren’t many decisions when choosing an underlayment for your hardwood floor. Choose the best material for your job, and you’ll be happy with your purchase.
Let’s cover the characteristics and pros and cons of hardwood underlayments:
Felt
This is the most popular hardwood underlayment.
If you are not using a floating floor, and most of the time with hardwood you won’t be, then one of the best types of underlay is heavy, black felt. These help keep moisture from coming up through the subfloor even when you nail directly through it, and can be stapled to the subfloor so they stay in place.
Black felt underlayment looks a lot like roofing underlay but does not have any asphalt or tar. It is odorless and safe to install in confined areas of the home.
Felt underlayment provides protection, but it lacks in bells and whistles. It’s thin and won’t give you much cushion underfoot or sound-dampening. If these are high on your priority list, you might want to move on to another material.
Cork
Cork isn’t quite as popular as felt, but it makes a great underlayment.
Cork is natural and renewable so it fits in well with a “green” home remodel.
Cork underlayment has excellent sound-reduction properties. It is even used in music studios to keep out background chatter from finished recordings. The best sound-dampening will come with 6mm cork underlayment, but you can also buy cork underlayment with 3mm thickness if you need a narrower underlay.
If you are trying to even out minor subfloor imperfections, cork is flexible and will fit evenly between the subfloor and the hardwood floor. It also helps to insulate against cold and heat and is water resistant. It’s not waterproof, but you can buy cork with a moisture barrier.
One last benefit of cork is for those suffering allergies: it has anti-microbial and anti-fungal properties.
Rubber
Rubber is easy to install, provides an excellent moisture barrier, and does a good job reducing sound.
So why is it the third most popular hardwood underlayment?
Mostly due to cost. It’s not way more expensive, but expect to pay around $1.50 for rubber underlayment.
The other benefit of rubber underlayment is it’s easy to DIY. Most underlayments are, but sometimes you have to glue down the others where rubber you just cut and set it down.
SMELL – one downside of rubber – depending where you buy it and it’s origin, it may sometimes smell “funny” or even “nasty” (in case in came from some sweatshop in China), and that smell may never go away. So if you get rubber underlayment, get it from a reliable source with possibility of return.
Cost of hardwood underlayment
Like anything in flooring, this varies a lot on quality, but expect to pay between $0.50 and $1.50 for underlayment. Cheap cork or felt could be lower, and you can pay more for special features but many of these will be marketing hype. Usually, you can stay in this range and get anything you need for your hardwood.
Radiant heating and wood underlayment
If you have radiant heating with your hardwood floors you can still use an underlayment, but you should pick one with a low R-value. A low R-value easily allows the heat to travel through the underlayment to the floor surface compared to a high R-value, which will actually work against the radiant heat by providing too much insulation.
Captain’s parting words!
An underlayment is very helpful when installing your hardwood floors. The slight addition of cost and time pays off in the long run by giving your floor some protection against moisture, reducing noise, increasing your comfort, and evening out any minor subfloor flaws without a major redo.
There are a few types of subfloor you can choose from. You should always check with the floor and underlayment manufacturers to make sure you are choosing products and installation methods that work well together. With that bit of preparation, you will be able to improve performance for both long after the floor is installed.
Next step? If you haven’t already, I’d check out our unbiased hardwood guide. It covers everything from the type of wood for durability to design choices.
Any questions I didn’t cover on hardwood underlayment? Let me know in the comments below.
We are laying a Quest Tigerwood Hardwood floor. What is the best underlayment to use over a particle wood subfloor?
Particle subfloor will be pretty versatile. I’d avoid the thinnest underlayments –you just need a little thickness to hide the imperfections. I like cork if I’m picking favorites.
Hello. I have a 1939 home with concrete slab floor with felt/mastic (I think) underlayment on top of that, then carpet. I want to tear up the carpet and install engineered or solid wood floor. Is the existing underlayment acceptable? If so, I presume I’d then use a moisture barrier, plywood to level it with other existing wood floor, then cork or something, then the flooring?
I find plenty of information for new installation, but none for an older home like mine.
Thank you
I’m removing my carpet and installing solid oak treads on my stairs. I’ve already nailed/screwed down the plywood to the stringers as best I can. But there’s no center stringer, and I can’t get access underneath to add more support. Will an underlayment help reduce creaking steps? Or is there something else I should do to prepare for the wood treads?
Installation isn’t my best expertise, but I know we have installers who read this so maybe one can chime in here.
We have a solid brick house from the 1860’s, the now un-vented crawlspace has been completely insulated and sealed, and has a dehumidifier installed. We built a new 1st floor structure with advantech subflooring. Our finish floor will be the original 1″x6″ (actual) historic poplar t&g floor boards. I would prefer to NOT have underlayment so the entire floor structure is free to dry towards the crawl or room. Do you think this is ok?
We are installing hickory 3/4″ solid hardwood flooring using nail-down installation on a plywood subfloor. We would like good sound protection, resistance to mold and moisture, insulation (one of the rooms is over the garage), and low VOCs. We have medical sensitivities to many chemicals and to molds. What would you recommend?
This is a little off-topic, but you might want to check out my article on carpet and VOCs, specifically the section that focuses on reducing VOCs–most of these steps will be applicable to hardwood installation as well (maybe I should make a page on this for hardwood). As for material, Wool can be a good material for low VOC but not as much for mold. Synethics are usually good for mold but not as good for VOCs. You might consider laying a moisture barrier to reduce mold risk and then using wool. On the other hands, you could go with a synthetic pad that resists mold but take the steps in the linked article to reduce VOCs.
Hi, we are installing oak hardwood floors in our brew home and we have concrete sub floors. I want to put something down to keep moisture out and the floors a little warmer during the colder months. We will be glueing our floor down and wanted too know what the best underlayment would be. Any suggestions?
You’ll really have a lot of options. You might look at cork, but even though cork has some moisture resistance, make sure to add a vapor barrier. For a less expensive option, you can find foam pads with built in moisture barrier which should be effective. Foam quality can vary. R-value is a number you can pay attention to: the higher the number, the better the insulation.
Hi Captain, I’m having Brazilian cherry wood installed on the 2nd floor bedrooms and solid oak wood installed on 2nd floor hallway to match the stairs and tailings. There is plywood under the carpeting I removed and found knots missing. Do I have to fill the knots? What is the best underlayment. Installer suggested 30W warrior felt but wood distributer suggested bellawood platinum underlay at almost $90 / 100 sq ft. Can I find something less expensive that provides the same benefits. Do I need the bells and whistles. Confused and frustrated. Thanks for any help you can provide.
I’d go ahead and fill the holes. It may not be necessary depending on their size, but cheap insurance and shouldn’t be too difficult to fix. With the pad you’re mentioning, you get certain bells and whistles like an improved moisture barrier and antimicrobial treatments. Unless you have a moisture problem (in which case I’d address that before considering hardwood), you can do without some of this. I would just look for a good, dense felt pad without bells and whistles if you want to reduce cost.
Hi Captain! I am having solid wood flooring installed upstairs in a two story home. I am choosing 3/4″ because I prefer the product to other options. Secondly, I want a 5mm rubber underlayment. The acoustical, and thermal properties appeal to me. I have other flooring in my home that I did 6 years ago with this approach and I really like it. However, the current installer is apprehensive because with hardwood you need to use staples to secure it. We used staples the last time and I don’t know why that is an issue this time. The manufacturer of the rubber product does state not to use nails, staples, or the like because it will cause a reduction in the acoustical properties. Can you give me some guidance here?
I guess the theory is penetrating the rubber underlayment also penetrates the insulation. I’m not sure that would make a huge difference. Your installer could have othe concerns though? I don’t personally install flooring, so I’d see what he thinks from his experience, but if it’s just the acoustic difference, I personally wouldn’t worry much about it.
Thank you for the speedy response. I did decide to go with the rubber because in speaking with the manufacturer they did say that there would be a reduction in the sound proofing but since I have already done this and am happy with the results, there is no other reason not to do it.
Hello, we are going to install an oak hardwood floor onto our plywood subfloor. Under the subfloor there is a crawl space. As we can’t get felt underlay here in NZ I was wandering if this product would do a good job as it it breathable.
https://www.thermakraft.co.nz/thermakraft-products/covertek-403-plus-roof?category=roof
Would love to get your thoughts about that option please.
Another question is: is an underlay not actually trapping the water which can come from the top (glass of water etc) between the floor boards and the plywood? Water might sit there forever…
That is one reason why I am not sure about using an underlay…
Furthermore we got 10% moisture content in the oak and 15% in the plywood subfloor. Is that still much and do we would need to dry the subfloor till it gets to 12%?
Thanks!
I’m not familiar with that but agree the breathable part is good. I’d hire a professional installer because the last thing you want to do is spend a bunch of money on oak flooring and then have it permanently warp from moisture. They’ll be able to test and give you the best options since yours is a borderline case.
Hi my carpenter is using paper as underlay, will this help in any way? Putting hardwood on second floor in a very dry climate
What is the subfloor? It may be to protect it. Otherwise, it doesn’t serve much of a purpose. It’s too think for cushion, sound, etc