Wood rot is a serious problem that can quickly destroy any wooden fixtures in your yard. Whether it’s decking, furniture, doors or windows, you need to take steps to tackle wood rot. Choosing the right type of wood for exterior projects is the best place to start. This article will list the top 10 best rot resistant woods and explain the benefits and drawbacks of each. It will also answer some key questions you may have about wood rot and how to avoid it.
Can Any Type of Wood Rot?
Yes, any type of wood can rot. Although some species of wood have a much higher natural resistance to moisture and fungi, all kinds of wood will eventually rot. Some will last a lot longer than others, but if you don’t take steps to proactively combat wood rot, it will set in eventually.
What Causes Wood to Rot?
Wood rot is a type of decay that is caused by fungus in the air. When the spores settle in the wood, they will grow and break down the wood, using it as food. This causes the wood to rot and become weak. If left untreated, the wood will lose its structural integrity and become useless.
In order for wood rot to set in, the wood needs to be constantly damp. The fungus thrives in damp conditions, which is why wood rot is particularly prevalent outside. Fungus also survives best in warm conditions and it needs oxygen. There are a few different types of wood rot to watch out for;
- Brown rot – Brown rot (also known as dry rot) happens when a specific fungi targets the cellulose in the structure of the wood. Although the surface looks dry, the wood is still damp to some extent. It breaks down into small pieces with a cube pattern and becomes weak and brittle.
- White rot – White rot leaves cellulose behind and attacks lignin instead. Cellulose has a yellowy white color, hence the name white rot. The wood will become very spongy and start to pull apart.
- Soft rot – Soft rot is less likely to affect wood around your home but it could still occur outside. It also breaks down the cellulose but it acts more slowly. The fungi that causes soft rot also survives in colder and warmer temperatures than other fungi.
Once the rot has set in, insects like termites will be attracted and they will also feed on the wood, causing the decay to speed up. Finding ways to prevent wood rot before it sets in is crucial.
What Helps Prevent Wood from Rotting?
There are two key elements that lead to wood rot; the fungi and the moisture that it needs to thrive. Unfortunately, there are so many different types of fungus and the spores are always blowing around in the air, so stopping them is an impossible task. So, that means you need to deal with the moisture if you want to avoid rot. Using a sealer or wood oil on exterior wood will stop it from rotting as quickly. Covering it so it is not in direct rain helps too.
The type of wood that you use for outdoor projects makes a big difference too. There are certain species of wood that are far less prone to rotting than others. Wood that has a higher natural oil content is more resistant to moisture, and wood that is very dense and has a tight grain soaks up water a lot slower. Ultimately, this means they are less likely to rot when used outside. Making the right choice can help you avoid issues for years to come. However, that doesn’t mean they are completely safe from wood rot.
10 Best Rot Resistant Woods
1. Pressure-Treated Pine
If rot resistance is your main priority over everything else, pressure-treated pine is the way to go. Natural pine is actually one of the worst options because it takes in a lot of moisture and is very prone to rotting. But once it has been pressure-treated, it is a whole different story. Pressure-treated pine is also quite a bit cheaper than many natural rot resistant woods.
The treatment process involves using pressure to force preservatives into the wood under high pressures. Instead of simply coating the surface, they are drawn into the cells of the wood, offering exceptional protection. The preservatives used, including alkaline copper arsenate, are designed to protect the wood against moisture as well as act as a fungicide and insecticide. Compared with natural wood, the protection you get from pressure-treated pine is excellent.
The only potential downside is that it takes on the color of the preservative and can have a green tint, which doesn’t look the best. If you are using it for a shed or a fence, for example, and you are going to paint it, this isn’t really an issue. But if you want a nice natural wood effect, you may want to consider something else.
Accoya is another type of treated wood that is becoming very popular because of its amazing rot resistance and durability. In fact, manufacturers claim that it will last for 50 years outside above ground. It is made through a process called acetylation, which involves exposing the wood to acetic anhydride and changing the structure. This makes it far less absorbent and blocks out moisture, so it’s a lot more durable.
Many people prefer it to pressure-treated wood because it is less toxic than pressure-treated wood. However, the chemicals used to pressure-treated wood have changed over the years and they are less harmful than they once were. Accoya wood is also more expensive than most of the options out there.
Mahogany is one of the most durable and rot resistant natural woods there is. It is incredibly dense and hard, with a tight grain that doesn’t let much water in at all. Compared with other woods, it’s also very strong and durable, making it an extremely useful wood for indoor and outdoor applications. It’s excellent for things like doors or furniture, and it’s common for flooring too. The aesthetic of mahogany is great as well as it has a nice rich red-brown color to it and an interesting, clear grain.
Mahogany is also a good wood to work with as it is easy to cut and sand, and it finishes nicely. The only reason that mahogany is not used as often as other woods is the price. It’s more expensive but you get what you pay for.
Teak is a much more common exterior wood that still offers the same rot protection as mahogany. In fact, it is often considered the go-to natural wood for rot resistance. It is not quite as strong as mahogany but it is still very durable and perfect for exterior uses where the wood needs to be hard wearing.
The appearance is a golden or medium brown and it tends to get darker as it ages. It’s also very simple to work with and finishes well. Again, it is quite expensive, but it’s a good all-around choice for exterior woodworking projects if it is in your budget.
Iroko is often used as a substitute for teak because it has similar rot resistance properties but it’s a cheaper alternative. The golden brown color is also very similar to teak, so the two are easily interchangeable. However, teak does beat Iroko on workability because Iroko has an interlocked grain that sometimes causes issues. Iroko also contains high amounts of calcium carbonate sometimes, and this can dull cutting blades easily. That said, it still makes an excellent low-cost substitute for teak, in many cases.
Ipe is a popular choice for decking because of its rot resistance and all-around strength and durability. It is a hardwood with a very tight grain that locks moisture out and prevents rot from growing. It is available in a range of shades, cut from different parts of the tree, so you can choose from lighter yellow colors all the way down to deep browns. The other thing that people love about Ipe is that it’s very sustainable, while some other types of wood are not.
You will find that Ipe is significantly more expensive than species like redwood and cedar, so if you’re on a budget, it isn’t your best choice.
7. White Oak
White Oak is a great rot resistant wood that is easy to get hold of. It is grown in the US in large quantities, so it’s fairly affordable and readily available, and it has excellent rot resistance too. The light brown color is ideal for any general woodworking projects and even though it’s not the most interesting looking wood, it still has a nice natural effect to it. It’s simple to work with too.
However, it does tend to shrink quite a lot, so if it is constantly exposed to temperature and humidity changes, it is likely to crack. You can avoid this, to some extent, by using a sealer to keep moisture out, but it’s something to be aware of.
Cedar is another wood species that is very rot resistant, but it is more prone to attacks from insects. Cedar is also a relatively soft species of wood, so it scratches and dents easily and doesn’t always sand brilliantly. This may not be an issue, depending on what you are using it for, but you should consider something else if the wood will get a lot of wear and tear.
Aesthetically, it has a red-brown color with dark stripes and a coarse grain, which makes it quite interesting. Cedar is often used for things like siding because it looks nice and the siding isn’t going to be walked on or moved around etc.
Cypress is a good mid-range option if you want to balance rot resistance and price. It’s more affordable than species like mahogany and teak, and it offers moderate resistance to moisture and wood rot. It has a light yellow-brown color but some pieces may be almost white if they cut closer to the center of the tree.
It’s good to work with and it accepts paint and stain well. If you are using it outside, giving it a layer of protection with some wood oil, sealer, or paint is advisable. However, it’s still relatively resistant to wood rot and it’s a more affordable option.
Redwood is commonly used for all sorts of exterior projects including decking, furniture, and fence posts. It has a similar rot resistance to cypress, but it does tend to be more expensive. The main difference between the two is in the aesthetics. Redwood has a nice pinkish brown color which varies in depth, and the grain is more interesting. It is easy to shape and sand and it finishes well. It is still most likely cheaper than mahogany and teak, but still more expensive than Cypress or pressure-treated pine.
What are Some Other Woods Across the World that are Rot Resistant?
There are many other types of wood around the world that are rot-resistant. Common ones not included in the list above are:
- Black walnut
- Black cherry
- Spanish cedar
- European larch
- Black locust
What Types of Wood are More Likely to Rot?
Any wood that is soft and absorbent, and has a lower concentration of natural oils is more likely to rot. These types of wood will soak up a lot of moisture and create the perfect conditions for the fungus to live and feed on the wood. Types of wood that are more likely to rot include:
Ideally, you should avoid using these types of wood outside and if you do, they require a lot of treatment to stop moisture from seeping in and causing wood rot.
What’s the Cheapest Rot Resistant Wood?
Pressure-treated pine is the cheapest option for rot resistant wood. There is a significant price difference when compared to all other rot resistant woods, which is why it’s such a popular choice for exterior projects.
What Rot Resistant Wood Should You Use for Raised Garden Beds?
Cedar is a popular choice for raised garden beds because it is rot resistant and it is relatively cheap. However, you can also use pressure-treated wood as it is even cheaper and it also does better when exposed to constant damp conditions from the soil.
People often worry that pressure-treated wood is harmful to plants because of the chemicals used to treat it, but that is not the case as long as you avoid wood that has been treated with chromated copper arsenate (CCA). This is the additive that was used in the past but has since been phased out in favor of non-toxic alternatives.
If you decide to use something like cedar, it’s important that you treat the wood properly because it will be exposed to excessive moisture. However, it’s vital that you use non-toxic options, especially if you are growing vegetables to eat.
How to Prevent Wood Rot?
Choosing the right type of wood is the first step in preventing wood rot, but there are a few other things you can do.
Treating the wood is probably the best way to avoid wood rot because you block out all of the moisture. Clear coats that form a strong barrier on the surface of the wood are excellent for this. You can also use stain products that contain fungicides that will kill off any rot before it can take hold. Alternatively, you can use a good quality exterior paint that will create a protective layer against the elements and change the aesthetic too.
When it comes to things like wooden furniture that you only use in the summer, consider bringing it inside in the winter when moisture and rot is most likely to set in.
Read our related article: Wet Rot Vs Dry Rot | What’s the Difference?
Can You Stop Wood that has Already Started Rotting?
If you catch wood rot early, you may be able to deal with it. Using fungicide products will stop the rot from spreading so you can think about repairing the damage. Next, you should remove all damaged wood. In some cases, it is best to replace entire boards. For example, if you have a deck that has started rotting. In other situations (wooden window frames, for example) you can remove the affected area and then use wood filler to patch it up.
However, this only works if you catch the rot early and then clean away all of the fungus with a strong fungicide. If the rot has been left for a while, it is usually better to replace than attempting a repair.
Douglas Fir vs Cedar Rot Resistance?
Douglas fir is considered to have moderate resistance to moisture and rot, but it is quite prone to insect damage. In general, cedar is more resistant and is the better choice for any exterior projects.
Spruce vs Pine Rot Resistance?
Neither spruce or pine are particularly resistant to rot and are not great for exterior uses unless they have been sealed properly. However, pine is slightly more rot resistant, and if it is pressure-treated, it is far superior.
Redwood vs Cedar Rot Resistance?
Both redwood and cedar are rot resistant and good for outdoor use. However, cedar tends to be slightly more resistant to moisture and rot than redwood.
Finding the right rot resistant wood is key for exterior projects. Although you should always treat the wood to improve its longevity, starting with a durable species of wood makes life a lot easier. In general, pressure-treated wood is the cheapest and most resistant wood. But if you want something that looks nicer, then teak, or Iroko if you want something cheaper, are always good choices.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.