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.
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.
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What happens to polyurethane over time? Does it become less waterproof?
Over 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
White 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).
Harder 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
I 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)
I 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?
Yes, 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?
No, 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.
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:
- Most popular sheens and finishes for hardwood floors
- What is a screen and recoat and when does it make sense?
- Best brands of polyurethane for hardwoods
- Which brands of polyurethane don’t yellow
- Best vacuum for hardwood floors
- Do shinier floors last longer? Are they more durable?
Does Polyurethane Make Wood Waterproof?