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Does Polyurethane Make Wood Waterproof?


No, polyurethane does not make hardwood waterproof, but it does make wood water resistant.  Polyurethane gives hardwood its protection.  It repels water and prevents water absorption, but it never fully blocks it so it will never make it 100% waterproof.  Polyurethane also protects wood for scratches and discoloration.  And, of course it makes the wood look finished.

Does Polyurethane Make Wood Waterproof

Just one layer of polyurethane isn’t sufficient.  Polyurethane is a thin layer and is discontinuous (with minor holes).  Even small scratches and abrasions will allow water to penetrate the surface if you only have 1 coat.  And, of course wood expands and contracts creating more weak points.


When you add more coats of polyurethane (we usually recommend 3), it makes the wood semi impervious as the poly layer will be thicker and more cohesive.  The protection will be greater and it will last longer…meaning you won’t need to sand and refinish for a longer period of time.


Please note that this article contains affiliate links.  You can read my full disclosure at the bottom of the page.


What happens to polyurethane over time?  Does it become less waterproof?

Does polyurethane make hardwood waterproofOver time, the wood expands and contracts creating more penetration, and the polyurethane wears down due to natural abrasions (even just by walking on the wood).


Furthermore, when you add polyurethane to the floors, you aren’t coating all 4 sides of the wood.


So, naturally, if you have standing water on polyurethaned floors, the water will eventually penetrate the wood even if it’s from the sides.


This can result in swelling, warping, wearing off of polyurethane as well as discoloration (e.g. wood turning gray and eventually black.)


How to make hardwood floors more waterproof?

Although no hardwood is waterproof, here are 7 ways to make hardwood more resistant to water.

1. Use white oak rather than red oak

ways to make hardwood more waterproofWhite oak flooring is more resistant to water than red oak, due to its cellular structure.  Many of the pores are plugged with tyloses making it more resilient to water.  This why it’s often used in boats and canoes.  It’s better to use white oak for areas in the home that may be more susceptible to water such as kitchens, entryways and front door stoops.


Check out this article for more information about white oak vs red oak flooring.

Video showing white oak vs red oak in water absorption

You’ll see in this video that white oak flooring is more resilient to water.

2. Use harder woods (and avoid softer woods such as pines and bamboos).

how to make your hardwood floors more resilient to waterHarder woods tend to be more resistant than softer woods because the wood fibers are packed tighter together.  Softer woods, such as pines, absorb water more; and, bamboo seems to absorb a lot of water as it’s a grass and has a lot of pores for the water to penetrate.  Bamboo is exceptionally poor at resisting water and turns black fairly easily, even just from minor spills by a dog’s bowl or by the back door.


3. Add more layers of polyurethane

More layers means more protection (up to a point).  I generally recommend 3 coats of poly (and never more than 4).  When you do too many coats of poly, it can turn the floors even more yellow and even a bit goopy (and it takes longer for the floors to cure).  So, it’s smarter to do 3 coats initially and then get an additional coat 3-4 years later (see below on screen and recoat).


Read about the best brands of polyurethane here.


4. Hire a professional to sand and refinish your hardwood

is polyurethane waterproofI know some people are tempted to sand and refinish themselves.  They think it saves them a lot of money.  News flash:  It doesn’t!  (See Hiring a professional vs sanding your floors yourself).


Refinishing hardwood floors is not a good DIY job. It only saves you a bit of money and of course it will take you way longer to do vs hiring a professional (so you’ll be out of your home longer).  And, importantly, your floors won’t come out as well and they won’t last as long.


You see the machines the pros use are way better than the ones you can rent.  And, of course pros have honed their skills.  Net net, the floors come out better and the polyurethane penetrates and adheres to the wood better when you hire a pro.  And, naturally, your floors will hold up better and be more resistant to water and moisure.


5. Periodically screen and recoat your floors

This is a little known secret that most homeowners aren’t even aware of.  Screening and recoating (sometimes called buffing) is a preventative maintenance step to help make your floors last longer.


Basically, you buff the floors and add an additional coat of poly. This gives you more protection and may add an additional 3 years worth of wear on your floor.  It’s just a one day process, and you may only need to do it in the heavy traffic areas (e.g. 1st floor, Kitchen + family room, etc.)  Learn more here: What is a screen and recoat?


You want to do this BEFORE you floors get worn down and before you can scratches through the color.


6. Wipe up spills (and pet accidents quickly)

how to protect your hardwood floors from water and scratchesI think this one is probably obvious -wipe up any liquids ASAP as it can wear down the poly and seep into the wood.  This includes areas where water of snow may be trekked in (use entry mats in the doorways – both inside and out).  Clean your floors often, vacuum once/week (this is the vacuum I recommend for hardwood floors).


7. Avoid using waxes or products that promise to restore your sheen

Many people don’t realize that some of the cleaning products are actually hurting  their hardwood floors.  Avoid products that promise to restore your sheen or lustre. These products contain waxes that temporarily make your hardwood floors look better. But, they actually degrade the polyurethane on your floors…so you need to refinish faster and water penetrates more easily.  Just use a regular hardwood clear such as Bona .


Does polyurethane protect wood from water?

Does polyurethane protect wood from waterYes, polyurethane provides a protective layer on hardwood (as well as furniture) making it harder for water to penetrate into the wood.  But, it is not waterproof; rather, it’s water resistant.  If water sits long enough or penetrates areas that aren’t sealed (e.g. where polyurethane has worn down or has scratches), it can still damage the wood.


And, of course, if water seeps below the wood or from the sides where it isn’t sealed, it can still damage the wood.  The edges of the butt joints are particularly vulnerable as the wood’s pores absorb more moisture here.


Does staining wood make it waterproof?

No, the stain just gives the wood its color.  It doesn’t provide much (if any) water or scratch protection.  You can easily scratch through the stain color if you don’t add polyurethane on top.   So you start with the stain, and after it properly dries (usually 24 hours), you would add on 2 to 3 coats of polyurethane to protect them (3 is better).


Are shinier floors more waterproof or durable?  Does the sheen impact the water resilience?

does stain make your hardwood waterproofNo, this is a common misperception.  Some people (even installers) mistakenly believe that shinier finishes last longer. There are 4 sheens – glossy, semi gloss, satin, matte – and they are all equally durable.  It doesn’t matter which you sheen level  you use as they are each equally durable.  They are technically equally as durable.


However, contrary to this mistaken belief, less shiny finishes look better longer so these appear to me more durable, not less durable.  This is because shinier floors reflect the light more, so they highlight scratches, dents and imperfections more.


And for the record, it doesn’t matter if you use shinier or duller finishes on the lower layers.  These neither make your finish stronger or weaker.  Whatever is on the top layer will be the sheen level you see.  Don’t worry if your refinisher uses a different sheen for the 1st or 2nd coat. It will neither impact the ultimate sheen level nor durability.


You can read more about sheens (and see pictures) in this article:  Which polyurethane sheen are most popular?


Is water based polyurethane waterproof?

Neither water borne nor oil based poly are waterproof, but they are both water resilient.  There is also a misperception that water based poly isn’t as durable as oil based poly, and the truth is that it depends which brand of water borne poly you are using.

Does polyurethane protect wood from water

There are many mid and low grade water based polyurethanes that are inferior to oil based poly.  But, there are also a few high grade water borne polyurethanes, such as Bona Traffic HD, that are equally are high grade and equally as durable.


You can read more about the best (and worst) brands of water polyurethane in this post.


Final thoughts on polyurethane and water resilience

Polyurethane does not make hardwood waterproof, but it does provide a strong protection layer to make wood water resilient and protect your floors from scratches.   To give your floors the best protection, be sure to use 3 coats of a high grade polyurethane.  And,be sure to pick up spills and accidents quickly.  Removing your shoes and adding area rugs will certainly help as well.  And, of course cleaning and maintaining your floors will also help, and periodically (every 3 to 4 years), consider getting a screen and recoat to give your floors and extra layer of protection.


Related polyurethane articles:


Does Polyurethane Make Wood Waterproof?


7 thoughts on “Does Polyurethane Make Wood Waterproof?”

  1. Hi! I just want to second your comments on refinishing floors yourself. I actually did that once. After I finished, I promised myself that I would never do that again! It’s a very big job.

    1. Andrea – Yes, it’s much harder than people think. I’ve had a lot of people try it say that they would never do it again. And, I’ve had a lot of people’s floors that we needed to resand as a result of DIYers.

  2. Since wood expands and contracts with heat and humidity, does climate ever play a role in the choice of polyurethane products? For example, are there climates where oil-based would be better than water borne?

  3. Great post and very informative. Just an interesting observation. I’m a real estate agent and in quite a few older homes, I’ve noticed that Pine floors were often preferred in kitchens of all places. Since they didn’t have the products we have today, it must have been almost impossible those floors in good condition.

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