Is Walnut Wood Water Resistant (A Clear Answer)

Walnut wood is a lovely shade of brown that can brighten up any project. This is one of the reasons why this sort of wood is so popular. However, before you start making something with this wood, you should consider how it reacts to moisture, especially if you plan to make furniture in a damp place like a bathroom. So you want to know, is walnut wood water resistant?

In short, due to its hardness and medium durability class, walnut wood has reasonably strong water resistance. As a result, when exposed to water, walnut wood resists shrinkage, warping, and rotting.

This article discusses how moisture is absorbed by the wood, what consequences this can have, and how you can make wood even more resistant to moisture to give you a better understanding of the water resistance of walnut wood.

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How does wood absorb water

To understand how wood absorbs moisture, it’s helpful to know how the wood you’re working with was while it was still a tree.

You should think of wood as a conduit for water and nutrients that are received by the tree’s roots and must be transported to the leaves.

The wood includes very small cells that allow this to happen. These cells have thin walls and can communicate with one another by passing moisture and nutrients through them. Water can be transferred from the roots to the leaves in this manner, from cell to cell.

A cell can therefore release water, which happens when we start drying the wood and the cell becomes empty (and also shrinks, depending on the type of wood). The opposite is also possible, so if moisture gets on the dry wood, the cells can store the water again, resulting in expansion.

Wood is hygroscopic, meaning that like a sponge, its moisture content changes depending on the relative humidity of the surrounding air. When the humidity increases, the wood absorbs moisture from the air and when the humidity decreases, the wood releases water into the air.

So if you are wondering, is walnut waterproof, then you will understand that walnut and any other type of wood is sensitive to moisture. However, not all types of wood are equally sensitive to this. Moisture absorption is largely determined by the hardness of the wood, which is expressed in Janka rating.

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How does water affect wood

Water can have a variety of effects on wood, ranging from mild to severe. As previously said, this is dependent on the sort of wood. Each type of wood has a distinct hardness, which affects the wood’s long-term endurance. More information on sustainability may be found in my article A Clear Guide To Wood Durability Classes + Chart.

Before we answer the question, is walnut wood water resistant, it’s important to understand what water can do to wood. This allows you to determine whether walnut wood is the ideal choice for the project you’re working on even more accurately.

Wood expands as it comes into touch with water because the cells fill with water. This isn’t a problem for some projects, but it might have severe repercussions for others, such as cupboard doors that won’t open or wood cracking.

Mold growth, which leads to deterioration, is a more serious issue. As a result, the rotting wood will weaken and fall apart over time. There are, however, other varieties of wood rot, which I shall discuss later in this essay.

If you read the above, you probably now realize that wood that absorbs water can cost you a lot of money to restore. Water damage can be the result of a wide variety of things. It can be the result of high humidity or direct contact with water.

It is therefore good to start using the right type of wood for the purpose you have in mind. If you want to use walnut in a room where there is moisture, or if water will come into direct contact, it is good to know to what extent walnut wood is waterproof.

What causes wood rot?

Wood rot is a type of degradation brought on by a mix of moisture and fungi (microscopic organisms). Fungi cannot grow on dried wood, hence the wood must be kept moist at all times for them to establish themselves.

While there are certain fungi that are beneficial, such as mushrooms, others are harmful.
In nature, fungi are the clearers of fallen wood. However, when we make something with wood, we always want to prevent these fungi from destroying our project.The many species that cause wood rot are divided into three categories based on their impact on wood.

Brown rot

Because the wood’s surface seems to be dry, brown rot is sometimes known as “dry rot.” Brown rot fungi feed on the cellulose that makes up the structure of wood. When the cellulose in the wood breaks down, it shrinks, turning a dark brown hue and shattering into small cube-shaped pieces. This type of fracture is known as a cuboidal fracture.

Brown rot flourishes in temperatures ranging from 18 °C to 32 °C (65 °F to 90 °F), and it spreads quickly once it starts to grow.

Is walnut wood water resistant - Brown rot
Is walnut wood water resistant – Brown rot (source: Wikipedia)

White Rot

White rot appears when wood turns a whitish or light yellow color and feels spongy. White-rot fungi break down lignin, another component of the wood structure, leaving the light-colored cellulose left, while brown rot fungi attack cellulose. White rot, like brown rot, occurs at temperatures ranging from 18 to 32 degrees Celsius (65 and 90 degrees Fahrenheit).

Is walnut wood water resistant - White rot
Is walnut wood water resistantWhite rot (Source: Wikipedia)

Soft rot

Soft rot fungi destroy wood more slowly than brown rot and white rot fungi, but they flourish in temperatures between -17 °C and 45 °C, which are too hot and too cold for the other species to live (0 and 110 degrees Fahrenheit). Although it is most usually seen in fallen logs and trees, soft rot fungus chews down cellulose, giving the wood a honeycomb look.

Is walnut wood water resistant

And now the question of this article is, is walnut waterproof?
Due to its hardness and durability class 3, walnut wood is resistant to wet conditions and water drops. As a result, walnut wood resists shrinkage, warping, rotting, and other disasters pretty well when exposed to water.

However, because there is always the potential of wood-decaying or working, a decent finish is required. If you make sure it’s handled properly, you can raise the water resistance of walnut wood. Like that, you can avoid problems.

Wood finishing can be done in several ways. You can use an oil, wax, stain, or varnish for this. Which choice you have to make depends on your own goal, but also on the use of the object you are making. To discover more about wood finishes, I suggest you take a look at my article, 4 Types Of Wood Finishes. What To Use When And How?

In some cases, wood will come into contact with food. Then it is good to look for food-safe finishers. You do not want your food to be contaminated with toxic substances from the finishing layer. These can cause chronic poisoning.

Walnut is a sturdy and easy-to-work-with wood with a fine texture. It’s a common choice for furniture, wall panels, and cabinets because of this.


Walnut wood contains Juglone, a poisonous chemical that can cause long-term harm to humans. Because not only the sawdust, but also the wood itself, contains juglone, it is not advised for use as a type of wood for making products that come into touch with foodstuffs. I wrote an article about it here: Is Walnut Wood Toxic, Important health info.

Is walnut wood weather resistant

Walnut has great weather resistance because of its hardness and durability class 3. Untreated walnut wood can have an outdoor life of up to 15 years.

Walnut wood comes in different variants. For example, there is black walnut, butternut, or English walnut to name but a few. Each variant has a different hardness and durability.

On the website wood database, you can compare all types of walnut and make the best choice of which walnut wood is best suited for the project you are working on.

If you want to compare walnut with oak, I can recommend you to check out my article, Walnut vs Oak, a quick guide to help you choose.

To compare walnut to mahogany, you should dive deeper into the differences by reading my article Walnut Wood vs. Mahogany: Which Is Better for Your Projects?

Frequently Asked Questions

How weather resistant is walnut?

Walnut wood is less prone to damage from temperature and weather conditions than teak or cedar, making it unsuitable for outdoor projects. Its best applications are indoors where it will not be exposed to extreme temperatures or humidity.

what drawbacks does walnut wood possess?

Walnut wood may be seen as having several disadvantages, due to its brittleness leading to dints and scratches and its usually greater cost than other woods. Moreover, in certain regions it can be challenging to get hold of this type of timber.

Is walnut a good exterior wood?

Although Walnut is not especially durable outdoors, it can still be effectively utilized outside provided it receives the appropriate care and maintenance.

Is Black Walnut wood waterproof?

Black walnut is not impervious to water, yet it offers a good degree of water-resistance. It can tolerate some dampness without deteriorating, but it is not advised to place the material in prolonged contact with liquid.

Is walnut wood mold resistant?

Walnut possesses a certain level of defense against the proliferation of mold owing to its inherent oils and resins, although it is not totally impregnable to mold.

Does walnut wood fade in the sun?

Walnut wood can fade over time when exposed to direct sunlight. This is a natural process and can give the wood a beautiful patina over time.

Can walnut wood get wet?

Walnut wood is capable of tolerating some exposure to moisture, yet if continuously exposed to water over a prolonged period, it will start to degrade.

Does walnut absorb moisture?

Walnut can absorb moisture, but it is less prone to moisture absorption than some other woods due to its natural oils and resins.

What is walnut wood best suited for?

Walnut is an incredibly versatile material, ideal for constructing furniture, floors, cabinets and various decorative items.

Is walnut more durable than oak?

Oak is generally considered to have more longevity than walnut due to its dense and hard grain. Despite this, walnut still proves to be a sturdy material that can withstand heavy use.

How do you protect walnut wood from water?

To guard walnut wood from water damage, seal it with a protective finish and avoid long-term exposure to moisture.

Is walnut wood rot resistant?

Walnut is not inherently rot-resistant, but it can resist rot to some degree due to its natural oils and resins.

Does walnut wood need to be sealed?

Yes, walnut wood should be sealed to protect it from moisture and other forms of damage.

How do you seal walnut wood for outdoor use?

To seal walnut wood for outdoor use, it should be treated with a water-resistant finish that is designed for outdoor applications. This may involve multiple coats and regular maintenance.

Is walnut an expensive wood?

Due to its rarity and captivating beauty, Walnut is frequently seen as a luxurious wood and can be pricier than other types of timber.

Is walnut wood antibacterial?

Walnut’s natural antibacterial qualities make it an excellent material for cutting boards and other kitchen surfaces.

What happens to walnut wood over time?

With age, walnut wood can darken and gain a stunning patina. However, if neglected, it can become brittle and more likely to fracture.

Does walnut darken over time?

Yes, walnut wood typically darkens over time as it is exposed to light and air.

How do you care for walnut wood?

To care for walnut wood, it should be regularly cleaned and dusted with a soft cloth. It should also be protected from direct sunlight and moisture, and periodically treated with a high-quality wood polish or oil.

Should you oil walnut wood?

Oiling walnut wood can help to protect it from moisture and other forms of damage, and can also enhance its natural beauty. It is essential to utilize an exceptional oil particularly formulated for application on wooden surfaces.

How porous is walnut?

Walnut is a moderately porous wood, which means that it can absorb some moisture if it is not properly sealed and protected.

Which wood does not rot in water?

Teak, cedar, and redwood – all naturally resistant to rot – are often utilized for outdoor purposes like constructing decks and borders.

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