How to Waterproof Wood: 3 Old but Gold Methods You Should Know

Learning how to waterproof wood is one of the best ways to keep your tables, decks, and furniture from warping, cracking, or rotting. Water is the #1 enemy of any wooden surface, and it does its damage slowly, then all at once.

Luckily, you can waterproof wood at home with a few simple supplies and no contractor.

In this guide, our team walks you through 4 proven-effective methods of how to make wood waterproof for indoor and outdoor. We show you which one fits your project, and help you avoid the mistakes that turn a nice piece into a water-damaged wood table top. Keep reading below!

Why You Need to Waterproof Wood

In fact, water damage is the #1 enemy of wooden surfaces, and it ruins wood faster than almost anything else. Without the right protection, your beautiful wooden table top, deck, fence, or furniture can turn into an expensive repair nightmare.

Water ruins wood faster than almost anything else

Photo: Freepik

Below are 3 popular reasons why you should learn how to make wood waterproof: 

Stop expensive damage before it starts:

• Wood cracks, warps, and splits when it soaks up too much moisture

• Wet wood rots from the inside out, weakening the entire structure

• Swollen wood breaks apart at the joints and creates uneven, dangerous surfaces

Keep your wood looking good:

• Water leaves ugly, dark stains that never fully disappear

• Sun and rain work together to fade wood's natural color

• Untreated wood turns a nasty gray that makes everything look old and neglected

Protect your health and safety:

• Damp wood grows mold and mildew that can make your family sick

• Bugs love wet, rotting wood and will move right in

• Damaged surfaces become rough and splintery, creating injury risks

You might like: How to Protect Wood Table Top

The Fastest Way to Choose Your Wood Waterproofing Method

First things first, let’s take a second to match the method to the surface you're working with. Waterproofing a cutting board doesn't call for the same approach as sealing a piece of wood furniture that's going to sit in your backyard. Use the quick guide below to find your starting point, then jump straight to that section.

How to Waterproof Wood: 4 Effective Methods Every Time

Let’s tour with 3 most efficient methods to seal wood from water: Natural wood oils, waterproof wood sealer, and waterproofing outdoor wood paint.

If you want to watch, we’ve made a video about the 3 most common ways to waterproof wood right here:

Otherwise, for our readers, let’s go over the top 3 ways for waterproofing indoor and 1 for outdoor furniture:

1. How to Waterproof Wood Naturally with Wood Oils

The easiest and most natural way to waterproof wood is with a penetrating oil, and it’s what people want when they search for how to waterproof wood naturally.

Oils like tung oil, linseed oil, and Danish oil soak into the grain and harden inside the wood, so they protect from within instead of sitting on top. The finish stays matte and keeps that warm, natural feel. A waterproof wood oil is also the only safe choice for anything that touches food. 

The 3 best natural oils to waterproof wood:

• Tung Oil: The gold standard, which gives the longest-lasting protection of all natural oils you can buy.

• Linseed Oil: What your grandfather probably had on the shelf in his garage. Time-tested, reliable, and still one of the best at keeping water out of wood.

• Danish Oil: A smart blend that does two jobs at once. It protects the wood from moisture and brings out a gorgeous finish at the same time. 

Covering the floor with natural wood oils

Photo: Shutterstock

Below is how we apply oil on our own wood pieces with natural wood oils:

Tools needed:

• Tung oil, linseed oil, or Danish oil

• 400-grit sandpaper

• Lint-free application cloths

• Tack cloth for dust removal

• Nitrile gloves

• Mineral spirits (for cleanup)

Step 1: Get your Wood Ready

• Give the wood a good cleaning to get rid of any dirt, grease, or old finish. Oil absorbs evenly only on a clean base, so wipe it down the way we explain in how to clean a wood table.

• We check that the wood is dry enough. It should be below 12% moisture if you have a meter to test it.

• Sand lightly with 400-grit sandpaper, always going with the grain to help the oil soak in better.

• Wipe away every bit of dust with a tack cloth, as any leftover dust will mess up your finish.

You might be interested in: How To Finish A Table Top Like A Pro

Step 2: Oil Application

• Stir your oil gently with a stick (never shake the can, or you'll get bubbles that ruin the finish)

• Brush or wipe on a thin coat, always following the direction of the wood grain.

• Work the oil into the surface using small circular motions to help it penetrate

• After 15 minutes, you wipe off any oil that's still sitting on top

Oil application for waterproofing wood table before

Photo: Lumer Grand

Step 3: Let the Oil Cure and Add More if Needed

• Wait for each coat to dry for a full 24 hours before adding another one

• We highly recommend a maximum of 3 thin coats. Applying more than that just creates problems without better protection

• Keep everything off the surface for 72 hours so the oil can fully harden

Oil application for waterproofing wood table after

Photo: Lumer Grand

2. How to Waterproof Wood with a Wood Sealer

When you need protection that lasts, a sealer is how to permanently waterproof wood. Synthetic sealers build a tough shell right on top of the surface, which makes them the strongest barrier you can get at home. This is also the route to take when you want to fully seal wood from water on a high-use piece. The not-so-good thing is that the wood won't feel as natural in your hand.

The common sealers are polyurethane, spar urethane, and marine varnish. Polyurethane suits indoor tables and shelves. Spar urethane and marine varnish flex with the wood and shrug off the sun, so they belong outdoors.

The 3 best synthetic sealers for different jobs:

• Polyurethane: Your best bet for dining table tops, counters, and anything that gets daily use and abuse. Also, if you’re a fan of polyurethane, don’t skip our beginner's guide on how to polyurethane a table.

• Marine Varnish: Built to handle boats in saltwater. It’s perfect for outdoor decks, fences, and patio furniture.

• Lacquer: What the pros use on expensive furniture when they want a flawless, rock-hard finish.

Read more: 5+ Best Polyurethane for Kitchen Table

Polyurethane is your best bet for dining tables

Photo: Lumber Grand

Here is how to permanently waterproof wood with a synthetic sealer:

Tools needed:

• High-quality waterproof wood sealer (polyurethane, varnish, or lacquer)

• Synthetic bristle brush or foam applicator

• 220 — 320 grit sandpaper

• Tack cloth

• Mineral spirits for cleanup

• Well-ventilated workspace

Step 1: Prepare your Wood Properly

• Strip off any old paint, stain, or finish. You should know that the sealer won't stick to dirty or glossy surfaces.

• Start with coarse paper and work your way up to fine grits for a smooth base.

• Wipe down with mineral spirits to remove every trace of dust, grease, and sanding residue.

• Work in a clean area where dust won't blow onto your wet sealer

Step 2: Apply the Sealer

• Pour some sealer into a separate container and stir gently

• Use a quality brush and apply thin, even coats following the wood grain

• Keep your brush strokes long and smooth. Also, you should overlap slightly to avoid streaks.

• Work fast enough to keep a "wet edge" so each section blends into the next

Read more: 5+ Best Polyurethane for Table Top: Oil-based & Water-based Picks

Step 3: Build Up Your Protection

• Wait 2 — 4 hours minimum between coats

• Lightly sand between coats with 320-grit paper to help the next coat stick

• Apply 2 — 3 thin coats total for complete water protection

• Keep everything off the surface for 72 hours while it fully hardens

Some advice to get the best results for waterproofing wood. You’ll need to:

• Work when it's 65 — 75°F. This is because too hot or too cold messes with how the sealer flows.

• Keep humidity under 85% or the sealer won't cure properly

• Stay out of direct sunlight while applying, or it will make the sealer dry too fast.

3. How to Waterproof Wood with Wood Paint

Sometimes, you want to change your wood's color and at the same time, protect it from water damage. Waterproof paint for wood kills two birds with one stone. This means it can give you beautiful color plus serious moisture protection. 

Top 3 waterproofing paint for wood that you should try:

• Acrylic-Based Waterproof Paint: Cleans up with soap and water, dries fast so you can finish projects quickly

• Oil-Based Protective Coatings: Soaks deeper into wood fibers and lasts longer, especially outdoors (DO NOT use water based)

• Stain/Sealer Combinations: One product that colors and seals at the same time
  

Waterproof paint for wood gives you beautiful color plus serious moisture protection

Photo: Lumber Grand

How to waterproof wood with waterproof paint:

Tools needed:

• Waterproof paint or stain/sealer combination

• 3/8-inch nap roller or quality brush

• 5-gallon bucket for mixing

• Pressure washer (for outdoor prep)

• Painter's tape and drop cloths

• Complete safety equipment

Step 1: Clean the Wood Surface

• We power wash the entire surface to remove dirt, mildew, and loose material. Then, you need to wait 48 hours for complete drying.

• Strip off any old paint or stain that's peeling or flaking

• Sand everything smooth so the new paint has a good surface to grab onto

• Use painter's tape to protect windows, concrete, and anything else you don't want painted

Step 2: Prepare Your Paint Properly

• If you're using multiple containers, you need to mix them all in a large bucket. It’s good at preventing color variations across your project.

• Stir thoroughly to make sure all the pigments are evenly distributed

• Test your color on a hidden spot first to make sure you like how it looks

Step 3: Apply the First Waterproof Paint Coat

• Roll or brush on thin even coats across the entire surface

• Work fast enough to keep a wet edge where you're painting

• Use a brush for detailed areas and corners, a roller for big flat surfaces

• Follow the coverage amounts on the can

Step 4: Add the Second Waterproof Paint Coat

• Wait the recommended time between coats. We usually wait 1 — 4 hours, but it will depend on your paint type.

• Apply a second coat for better protection and even color coverage

• Don’t forget to walk around and check for any spots you missed, then you touch them up right away.

Here is some advice for getting the best results when working with waterproof paint. You’ll need to:

• You should paint when it's between 55 and 90°F.

• Make sure NO rain is forecast for 24 hours after you finish.

• Overcast days are actually better than bright sun because the paint won't dry too fast.

4. How to Waterproof Wood Furniture for Outdoors

Outdoor wood is not a separate method. It’s the 3 methods above used under harder conditions, because the wood fights rain, sun, and temperature swings every day. In such cases, you’ll need a product that blocks moisture and UV at the same time.

A bare sealer will keep the water out just fine, but it won't stop the sun from slowly graying out the wood underneath. So instead, we highly recommend using a spar urethane, spar varnish, or an exterior sealer-stain that has UV protection already built in. 

Recoat outdoor pieces every one to two years, and always reseal cut ends and joints, since that is where water sneaks in first. The same careful thinking carries over to any surface you want to hold onto for the long run, which is why it pairs nicely with our guide on how to protect your wood tabletop long-term.

FAQs

1. What is the Easiest Way to Waterproof Wood?

The easiest way to waterproof wood is to wipe on a penetrating oil like tung oil, Danish oil, or linseed oil. Clean the surface first, then rub a thin coat along the grain, wait about 15 minutes, and buff off whatever the wood didn't soak up.

Two or three coats give solid everyday protection with no spray gear or pro skills. With tops that take daily spills, we’d step up to a wipe-on polyurethane, but oil is the simplest place to start.

2. How Do You Waterproof 100% Wood?

You can't make wood 100% waterproof, but you can make it very water-resistant. The best approach is to use a penetrating wood sealer followed by a good-quality exterior wood stain or paint. 

We can do it by cleaning the wood thoroughly, then applying a wood preservative that soaks deep into the grain. After it dries, you can add your topcoat. This waterproof technique keeps most water out and lets the wood breathe naturally.

3. Can You Spray Something on Wood to Make it Waterproof?

Yes, you can spray wood to make it waterproof using a clear sealer spray. Thompson's WaterSeal and similar products come in spray bottles that are perfect for decks, fences, and outdoor furniture. 

However, spraying wastes more than brushing, so it costs more. Besides, you'll need to reapply spray sealers more often. That’s usually every 1 — 2 years instead of 3 — 4 years for brushed-on products.

4. How to Seal Wood so It Doesn't Rot?

The best way to stop wood rot is to keep moisture out before it starts. And to achieve this, you’ll need to clean your wood and let it dry for at least 48 hours.
Secondly, you apply a wood preservative that soaks deep into the grain (it kills any fungus that causes rot). Once that's dry, you add a waterproof topcoat like polyurethane or marine varnish to create a barrier against water.

5. Can You Make Untreated Wood Waterproof?

Absolutely Yes! Untreated wood is actually easier to waterproof because there's no old finish to strip off first. And no matter if you choose natural oil, synthetic sealer, or waterproof paint, untreated wood soaks it up better and gives you longer-lasting protection.

How to Waterproof Wood: Guide Ends Here

So there you have it, protecting your wood from water damage really isn't as hard as it sounds once you know what you're doing. Pick the method that makes sense for your project and take your time doing it right the first time. Your future self will thank you when you're not sealing exterior wood with rotting boards or expensive repairs.

Want to learn more tricks for keeping your home in great shape? We've got plenty more helpful blogs that break things down for beginners, just like this one.

Do you have questions about how to waterproof wood or get stuck on something specific? Simply contact our dedicated team! We love helping folks figure out the best way to tackle water resistant wood.