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Engineered Hardwoods and Water: 5 Questions (Answered!)

If you have engineered hardwood floors in your home, or if you are considering having them installed, you are probably wondering how well they stand up to water.  Are they waterproof? Will a small amount of water ruin them? Are there areas of the home where you shouldn’t use them due to moisture?

In this article, I’m going to answer some of the most common questions that come up around engineered hardwoods and water. Let’s dive in!

Is Engineered Hardwood Flooring Waterproof?

No, engineered hardwood flooring is not waterproof.  In fact, no wood flooring is truly waterproof.  Properly finished engineered hardwoods are water-resistant but they are not waterproof. However, that does not mean you cannot use them throughout the house. They actually make a great flooring option for nearly any room. Let’s explore further.

Engineered hardwoods are made by gluing multiple layers of plywood, called the core board, together in a cross-grain pattern, and then gluing on a real hardwood layer on top. This actually makes engineered hardwoods more stable and durable than natural hardwoods because they’re less prone to shrinking and expanding due to changes in humidity levels.

Here’s a photo so you can get an idea of what I’m talking about here. You can see the thin layers of plies sandwiched together and the hardwood veneer, called the wear layer,  on top.

Engineered Hardwood Flooring Layers

As you’ve likely guessed by now, this does not add up to them being 100% waterproof. If enough moisture gets down into the inner layers, the wood and adhesives will start to break down over time, damaging your floor.

Most modern engineered hardwoods do have a good degree of water-resistance so you shouldn’t shy away from using them in nearly any room.

In fact, the only room I absolutely recommend not using them is in the bathroom.  There’s just way too much moisture and humidity there for it to make sense.

You also need to consider moisture coming from under the subfloor. Check out this article I wrote on vapor barriers for more information.

Just how well your engineered hardwood flooring will stand up to water really depends on the finish/sealer used, and whether or not they’re in good condition.

I think the most common and obvious exposure to liquid on your hardwoods will be people spilling stuff on them, so next, we’ll tackle that.

Will Spills Ruin Engineered Hardwood Floors?

This is an interesting question, and certainly one of the most common, and also one that it’s hard to give a definitive answer for.

Obviously, if you spill a glass of water on the floor and clean it up immediately, your floors will be fine.  However, if you manage to spill a 50-gallon fish tank on the floor, well, let’s just say you’re in for a bad day.

Yes, those are two extreme examples. But the truth is, it’s hard to say. It all comes down to how much liquid you spilled, how long it sat on the floor before you cleaned it up, and how well your floors are finished or sealed.

Since I happen to have quite a few scraps of engineered hardwood leftover from when I installed them last year, I thought it’d be fun to run an experiment.

This will help you (and me) understand just how quickly (or not) a spill might ruin your engineered hardwoods.

Engineered Hardwood Floor Spill Test

First a few ground rules: this is in no way scientific, and my floor and your floor may not be equal. So, please use this information only as a rough guide, not gospel. For the record, my engineered hardwood is Shaw Expressions Harmony which uses a UV-Cured Aluminum Oxide finish (see the next section).

Spill Test Setup

  • Using two pieces of scrap flooring, I set them up as shown in the photo below. This mimics a floating floor setup since they are not nailed, stapled, or glued to my workbench. They also may not be as tightly joined as they would be after installation, but I did hammer them together with quite a bit of force. I used only two due to limited work area and these are 7.5″ wide planks.
  • I then sectioned it off into 4 sections so that I could test spills that sat on the floor for 5, 15, 30, and 45 minutes. My assumption is that in most scenarios, you’ll most likely have cleaned up a spill within 45 minutes. I put the flooring on white rags so we can really see how much liquid seeped through.

Running the Test

  • I added roughly equal amounts of water I dyed blue with food coloring using a turkey baster and started the timer.
  • I then completely cleaned up each area at their given interval – 5 minutes, 15 minutes, 30 minutes, and 45 minutes.

Note that I’ve maxed out blue and green saturation in these photos to really show the blue-dyed water

engineered hardwood spill test start

Here’s a photo from the 15-minute mark. Notice how much liquid in the 30-minute and 45-minute sections has been lost through the gap.

Engineered Hardwood Spill Test 15 minutes

Spill Test Results

Not surprisingly, the longer the liquid sat, the more it seeped through the gap and down to the rag, which represents your subfloor.

The 30 and 15-minute areas seem to bleed together in this photo, but in my opinion, more is coming from the 30-minute section. This is likely due to my work table not being perfectly level.

It does appear to me that really the culprit of liquid getting down to the rag (your subfloor) was the gap. I cut one of the planks up, and I don’t see evidence that it seeped through the surface. Only the bottom felt wet to the touch.

End of spill test

Cross-section of the 30-minute area

30 minute cross section

Cross-section of 45-minute area. Moist in the groove, as expected, but not on the inside section.

45 minute cross section

24 Hour Engineered Hardwood Spill Test

Given that I didn’t see any evidence of the water actually penetrating the surface of the engineered hardwoods, I decided to expand the test out a bit.

I wanted to see if the liquid would stand on the plank for 24 hours or if it would eventually soak through the veneer and down into the core board.

It’s hard to imagine a scenario where you wouldn’t clean up a spill in 24 hours or less, so I thought this may help us understand just how well engineered hardwoods stand up to spills.

24 Hour Test Setup

  • Since we already know that water is going to seep into the crack relatively quickly, I just put water on a single plank, and only on the surface. I just wanted to see if spilled water would seep into the board and ruin it within a 24 hour period.

24 hour spill test start

  • I then simply let this sit for 24 hours and then cleaned it up.

24-hour test Results

I was really pleased to find that the water was still sitting on the board after 24 hours with no evidence of having soaked into the engineered hardwood plank. Note that I cleaned up the drops of water you see around the words “24 hour start 5:40 pm” after I started the test. They did not seep into the wood.

After 24 Hours

24 hour spill test end

Next, I drew an outline around the liquid and cleaned it up.  I did this so I could cut the board up and know exactly where the water was sitting.

Cleaned and liquid outlined. Note there’s no discoloration on the surface.

I cut the board up into section so I could examine the inner core board

Cut up board

As you can see below, there doesn’t appear to be any evidence that the liquid penetrated the outer veneer. I see no discoloration on the top or in the core board cross-sections. The inner wood is also dry to the touch.

24 hour test dried

Overall I’m pleased with the outcome of both the short-term and 24-hour spill tests. I do think that spills could in theory ruin your engineered hardwoods, but as long as you clean it up quickly and then allow the area to dry, you should be okay.

I think it would take a large amount of liquid or letting it sit for a long time to have a real concern.

I’ll state again that your floor and my floor are likely not equal, so please don’t try this experiment at home.

What Should You Do if You Spill Liquid on Your Engineered Hardwood Floor?

Ok, given my experiment, we can now say pretty confidently that while liquid may bead up and sit on the veneer of the hardwood, it will almost certainly seep down through the gaps between boards and find its way to your subfloor.

So, what should you do if you have a spill?  Here are a few tips to help minimize the risk of permanent damage, such as buckling, due to the spill.

Clean up the Spill or Leak as Quickly as Possible

This goes without saying, but the first thing you must do is thoroughly clean up the spill and dry the floor as much as possible. This will prevent any further damage from occurring and get rid of the source of moisture.

Use a Wet Vac

If you have a wet vacuum such as a shop vac, run this over the gaps in the flooring over the entire area affected by the spill. This helps to suck up any additional liquid that’s sitting in the gap and hasn’t yet worked its way down to the subfloor.

Use Fans

Run as many fans as you have in the room, and point them at the floor in the direction of the spill. The air moving across the floor will help dry it out faster and help to minimize damage. If weather permits, opening windows will also increase airflow through the room.

Use a Dehumidifier

If you have one, placing a dehumidifier in the affected room will also help. These remove moisture from the air and help dry out the room. One thing to remember is that you will have to empty the water reservoir every few hours or so.

If there’s a lot of humidity in the room, this can fill up quickly. If you don’t own a dehumidifier and the spill was significant, you can usually rent one at your local hardware store. Let if run for 3-5 days.

Call in a Professional

When in doubt, or if you’ve spilled large amounts of water on your floor, or an appliance such as a refrigerator on your hardwoods and it leaked, it’s likely time to call in a professional to assess the damage.

Should you Seal Your Engineered Hardwood Flooring?

Do you need to seal your engineered hardwoods? Maybe. You’ll first want to determine if they’re already sealed or not. If you know the brand of your flooring then this should be pretty easy to find out on the manufacturer’s website or from a local dealer who sells the same flooring.

If you don’t know the brand, then you can put a small amount of water on the floor in an inconspicuous spot – like in the corner of a closet or somewhere similar.

Please do not do this out in the middle of your living room! Anyway, put the water on the floor and see if it beads up and just sits on the surface, or if it appears to soak in.  If it sits on the surface, your floors are most likely sealed already.

Make sure you completely clean the water up after performing the test and don’t let it sit too long. You don’t want to damage your floors.

If you do know the brand, then check for the type of finish used by the manufacturer.  One common finish applied by the factory is UV Aluminum Oxide. Aluminum oxide is a mineral found naturally that hardwood manufacturers cure to the planks using UV, hence the term UV or UV-cured aluminum oxide.

This process creates a hard coating on the top layer of the engineered flooring that not only protects it from scratches and scuffs but also seals it from moisture. I demonstrated this in the experiment above. The water literally sat on the surface of my engineered hardwoods without evidence of penetration for 24 hours.

If you have determined that your floors are not sealed, then you could consider doing so. I do recommend that you consult with a professional because it’s important to use the proper type of sealant.

One of the most common, and best, in my opinion, options is water-based polyurethane. It’s easy to use, great for a DIY project, it’s relatively inexpensive, and it’s also low odor and has low amounts of VOCs. Other common sealers include oil-based polyurethane, wax, shellac, and penetrating oil sealers.

Common Sealers/Finishes

Sealer TyperEase of ApplicationProtectionOdor/VOCsColor Alteration?FinishCost
Water-Based PolyurethaneEasy, Dries QuicklyProtects against moisture but not scratches, easy to maintainLowNoneSemi- to High-GlossLow
Oil-Based Polyurethane (flammable)Difficult, Dries SlowlyProtects agains moisture and scratches, easy to maintainHighMay cause yellowing laterSemi- to High-GlossLow
WaxDifficult, Dries QuicklyProtects but requires frequent maintenanceLowMay darken floors over timeMatte / Low-GlossLow
Penetrating OilEasy, Dries SlowlyProtects but requires frequent maintenanceLowMay reduce shininessMatteHigh
Shellac (flammable)Medium, Dries QuicklyProtects but requires frequent maintenanceLowMay alter the tint MatteLow

Again, I highly recommend consulting with a flooring professional before attempting this. Using the wrong type of product on your engineered hardwoods could damage the floor and void your warranty (assuming it’s still under warranty).

Can you Safely Clean Your Engineered Hardwoods with a Swiffer Wetjet, Steam Mop, or Mop and Bucket?

Another common question about engineered hardwoods is whether or not you can clean them with mops. We’ve already established that engineered hardwood floors are not waterproof, but that doesn’t mean all mop cleaning methods are a no-go.

Swiffer Wetjet (or similar microfiber wet mop)

Using a Swiffer Wetjet is fine for engineered hardwoods, as long as they’re sealed and not waxed or oiled. These don’t produce enough liquid to leave puddles of standing solution on the floor. The one caveat here is to make sure you’re using the cleaner that is specifically designed for wood floors.

Another great option is the Rejuvenate Click and Clean Mop system. This is very similar to the Swiffer Wetjet. It comes with a microfiber cleaning pad and you simply insert the appropriate bottle of cleaner.

I use this very model at my house along with their Professional Hardwood Floor Cleaner, and it produces great results. After you’re finished, just throw the microfiber mop head in the washing machine.

Lastly, Bona also makes wonderful hardwood cleaner and microfiber head wet mop that is great for engineered hardwoods.

There are two important tips for cleaning your engineered floors with a microfiber mop:

  • Before cleaning your engineered hardwoods with the Swiffer Wetjet or other microfiber wet mop, clean the floor of loose dirt by either sweeping really well, or preferably with a vacuum. This will produce much better results and also prevent loose dirt and debris from potentially scratching your floor as you mop. Vacuuming is far superior to using a broom!


  • Go easy on the spray button. All of the mops mentioned above have a button to activate the sprayer to apply the cleaning solution to the floor. Take it easy and only use enough to lightly coat the floor in front of you. The goal is to use enough to break up the dirt and grime on the floor, not soak it!

Steam Mop

Nope. Do NOT use a steam mop on engineered hardwood floors! I know, I know, you’ve read on forums or other sites about people who have been using steam mops on their floors for years and have no issues. Good for them, don’t do it!

Scroll up to the photo I posted near the top showing the cross-section of a plank of engineered hardwood. Remember that all those thin layers of plywood are held together with an adhesive.

A steam mop forces hot moist air (steam) down into the wood floor. Over time, repeated exposure could cause the underlying plywood to swell or degrade the adhesive. In fact, the warranty card for my floor specifically calls this out as a no-no.

Mop and Bucket

Just like the steam mop, DO NOT use a mop and bucket to clean your engineered hardwood floors! If you think steam is bad for them, perhaps the only thing worse is a large volume of water standing on them. Thankfully I don’t think you’ll find anyone online recommending that you do this. This is also another potential warranty killer.