Breaking News
Home >> Ask Bob & Betsy Series >> Do Hardwood Floors Need Moisture Barrier?
Blog Header - Ask Bob & Betsy

Do Hardwood Floors Need Moisture Barrier?

Dear Bob and Betsy,
I’ve read a lot about how dangerous water is to hardwood floors. I’m planning to install my new flooring “on grade” (not above), which I know is a little bit risky. I feel confident they won’t get damaged where I live. Do hardwood floors need moisture barrier if I’m installing them on grade? Thanks!
– Susan C.

Dear Susan,

You’re right. Moisture can do serious damage to hardwood flooring if you’re not careful. If you were to install your flooring below grade, we’d caution you heavily against it. However, on grade installations can be safe as long as you’re confident that the moisture levels won’t damage your floors.

Moisture barriers protect your flooring from below.

You are probably diligent about keeping your house clean and free of standing puddles. You might also have a plan in place for what to do if someone spills on your hardwood floor. Still, you can’t always know what’s lurking below the surface.

Although you check (and double check, and triple check) your subfloor for damage, such as cracks or dips, before you install, damage can still happen over time. After you’ve had your flooring for several years your subfloor might get a tiny crack that could let in just the right amount of moisture to harm your floors.

Moisture barriers protect your flooring from below. They keep your hardwood safe even if a little bit of moisture seeps up from the subfloor. This is the type of moisture you won’t know is lingering until it’s too late.

These benefits sound ideal but should you use a moisture barrier for your hardwood flooring installation? It depends on your subfloor and how you plan to install your flooring.

Installation

If you’re planning to nail down your hardwood floors, a moisture barrier is recommended.

If you’re planning to glue down your hardwood floors, things get a little trickier. Many solutions today require the use of a trowel spread barrier. Talk to your installers about this before they arrive at your house so you’re sure your flooring is protected correctly from below.

If you are installing an floating engineered hardwood flooring, you can use Aquabar underlayment to help control moisture.

Wood Subfloors

Sometimes, a moisture barrier is not recommended. If you’re installing your hardwood floors over a wood subfloor, you should avoid using a moisture barrier.

Over time, moisture can get trapped between the moisture barrier protecting your hardwood flooring and the wood subfloor. This can cause the subfloor to warp and rot, promoting mold growth and causing serious damage to your home.

Attached Moisture Barriers to Underlayment

You might also be tempted to use underlayment with a moisture barrier attached. This type of underlayment is great for floating floors, such as some laminate and engineered hardwood flooring. However, it’s not recommended for solid hardwood flooring because you will either need to nail or glue down the floors when you’re installing.

Did this help? Sign up for our newsletter for other hardwood flooring tips.

Learn More About Hardwood Flooring:

About Bob and Betsy

Bob and Betsy
Bob and Betsy are the dynamic duo that have all the answers for your flooring related questions! Don't hesitate to submit a question to them at support@bestlaminate.com!

Check Also

Ask Bob & Betsy Blog Header

How should I choose laminate flooring underlayment thickness

Dear John, Great question! Your underlayment sits between the laminate flooring planks and your subfloor. …

Ask Bob & Betsy Blog Header

What Should I Look For in Laminate Flooring Underlayment?

Dear Jon, When it comes to underlayment options, you have a lot to choose from. …

Ask Bob & Betsy Blog Header

Ask Bob and Betsy: Can I Use Laminate Flooring in a Bathroom?

Dear Ariana, You’re right. There’s no such thing as waterproof laminate flooring. But that does …

8 comments

  1. We’re renovating an 1845 home that we lifted off its foundation and rebuilt it. The ‘basement’ will have 11’ finished ceilings. We insulated under slab (2” foam and 16 mil vapor barrier). We insulated exterior walls (blue skin/dimple board/2” foam; wrapped footings and drylocked bond from footing to walls) basement has own hvac system, top two main floors – 2 zone. Basement walls interior have 1” foam and built out 2×4 walls to get further fiberglass batt before 1/2” green board. We are encapsulating all exterior walls and roof with closed cell foam. With such a tight building envelope (also adding batt between floors for sound and to keep temps consistent)… what would be a good underlayment for an engineered hardwood? I’m leaning toward wanting the floors to ‘breath’ more as we spent a lot of effort on the exterior envelope. Any suggestions on best underlayment being used on green built homes?

  2. Removing carpeting and installing 3/4 Oak Flooring strips, 2 1/4 wide. Subfloor is sob, dry and in good shape. What underlayment should be used. I sold a 3 in 1, however reading your website it seems a paper underlayment would be adequate.

    Spacing: The new baseboard is narrower than 3/4″. Can spacing be 3/8″.

    Thanks

    Frank

    • Hi Frank – We would recommend AquaBar B underlayment. It is specifically made for hardwood flooring. As for the spacing, we would recommend checking your floor’s installation guide to see what is the proper expansion gap. If it recommends 3/4″ around the perimeter of your home, you should go by the installation instructions to avoid voiding your warranty and potentially creating issues with buckling or warping of your floor because of an inappropriate expansion gap, in later years. If you have any further questions, please reply to this comment! Happy installing!

  3. Hello

    I would like to lay a wood floor (by floating) in a cabin that is not temperature regulated throughout the year. I will be using tongue and groove pine wood. Part of the new floor will sit on top of plywood and the rest will be installed on top of vinyl. What do you recommend for vapor barrier/moisture barrier for these two different surfaces?

    Thanks

    • Hi Bethany. I will certainly answer your question, but I have some other concerns about your installation that I would like to point out first.

      First, I would really recommend that you do not install a wood floor in an space that has no temperature regulation, unless you live in an area that is very steady in its climate and humidity. Wood flooring (laminate, solid hardwood, and engineered hardwood) will expand and contract due to temperature and humidity conditions. If you live in an area where this fluctuates dramatically with season changes, your floor could buckle or warp due to these changes – ruining your floor. Consider COREtec flooring, which is a WPC + vinyl engineered floor, which is 100% waterproof and does not expand and contract the same way that wood flooring does, making it a better option for spaces that are not temperature controlled.

      Second, is the vinyl glued down or is it floating? If it is a vinyl that was glued down, then you can go ahead and install your new floor on top if the vinyl is even. If the glued down vinyl is not even, or if your vinyl was installed as a floating vinyl, you should uninstall it and install your new floor on top of the subfloor beneath. You can read all about subfloor preparation on our Help Pages.

      Now for your original question, you can use the same type of underlayment on top of both surfaces. Now you just have to decide if you need cushioning, added warmth, or if you just need a simple vapor block.

      If you need any additional help, please feel free to email us at support@bestlaminate.com or call us at 1-800-520-0961!

  4. Part of our home is over 100 yr old cabin. The logs were cut with a hew. The wall are all different in dept. The floor is very cold even though there is a basement under it. Could we use a laminate flooring. Also our kitchen floor has a dip in it . The laminate floor we put down keeps pupping up. What can we do to help. Thank you

    • Alana Kane

      Hi Margaret! The most important thing you would need to do is have a level and sturdy subfloor before installing any type of wood flooring. This would include adding OSB or plywood to your existing surface if it is not level.

Leave a Reply

Your email address will not be published. Required fields are marked *