Wooden furniture makes a great addition to your yard, but you need to look after it properly if you want it to stay in good condition. Damage caused by moisture and prolonged exposure to the sun can ruin the look of your furniture and damage the structural integrity. If you are not careful, it can rot and become unusable.
However, if you waterproof your wood furniture, you can protect it from the elements and keep it in good condition for longer. In this article, we will discuss why it’s important to waterproof furniture in the first place, and some of the easiest ways to do it.
Does Outdoor Wood Furniture Need to Be Sealed from Water?
Yes, outdoor wood furniture needs to be sealed from water. Exposure to the elements can ruin the finish of the wood, cause it to warp, and make it susceptible to rot. When water gets into the wood, it can cause the fibers to swell and break, which leads to decay.
Some wood furniture is made from pressure-treated timber, so it already has some level of protection against moisture. However, this protection fades over time and the wood will need to be sealed to prevent moisture from getting inside and causing the wood to decay.
What Happens if You Do Not Seal Outdoor Wood Furniture?
If you do not seal outdoor wood furniture from water, it will soon get soaked through and the wood will rot. You are also much more susceptible to mold and mildew because the presence of moisture creates the perfect environment for it to grow.
Any paint or stain that you put on your wooden furniture will also peel and flake off when exposed to excess moisture. Using paint or stain with a built-in sealer can help to prevent this.
Obviously, this is a big problem in the winter when it is raining a lot, but moisture is still an issue in the summer. When it is humid and there is a lot of moisture in the air, this can seep into the wood and cause decay. So, your furniture needs to be sealed whether you live in a rainy climate or not.
Sealing your outdoor furniture also protects against UV rays, which can cause the wood to fade over time.
How to Waterproof Wood Furniture for Outdoors?
There are a number of ways you can waterproof wood furniture so it is fit for outdoor use. All of the methods outlined below are simple, so as long as you have some basic DIY skills and a few simple tools, you should be able to manage it on your own.
1. Spar Urethane 
Spar urethane is a type of sealant that is used to protect the wood from moisture and decay. It comes in a variety of finishes, including matte, satin, and gloss. It is available in both clear and tinted versions, so you can choose the one that best suits your needs.
Spar urethane can be applied with a brush or a roller, and it dries quickly so you can get it done in just a few hours. It is also UV-resistant, so it will not fade in the sun. When applying spar urethane, make sure that the wood is prepared by sanding it down and removing any dirt or dust. You will need to apply at least two coats for good protection.
The protective coating should last for about two years before it needs to be reapplied. Spar urethane is a good choice for sealing wood furniture if you want a long-lasting finish that lets the natural wood show through.
You can see similar sealers on our top 10 best clear coats for outdoor wood furniture here.
2. Exterior Paint
Painting the furniture is a good way to give it some color and protect it at the same time. However, it’s important that you choose the right paint. It needs to be exterior wood paint, not interior paint. Oil-based paints are the best for outdoor furniture because they are more durable and waterproof. Latex-based paints also work well, just double check that they are specifically formulated for outdoor use.
You can either use paint with a built-in sealer, or you can apply a coat of sealant, like spar urethane, over the top of the paint. The sealant will need to be reapplied every few years, but it will help to protect the paint from UV rays and moisture.
It may be a good idea to use a primer too. This will help the paint to bond to the wood and will give it an extra layer of protection. Some paints are self-priming so check the directions on the tin first.
When painting your furniture, always make sure that it is clean and give it time to fully dry before applying paint.
3. Stain and Sealant Combination
Staining is the best way to bring out the natural grain of the wood, but if you are staining furniture for outdoor use, you should combine it with a sealant.
Start by staining the wood with a waterproofing stain. This will help to protect the wood from moisture and will also give it a protective coating. Once the stain is dry, apply a coat of sealant over the top. The sealant will need to be reapplied every few years, but it will help to keep the wood looking good for longer.
Polycrylic is an excellent sealant to use over the top of wood stain. It’s cheap to buy, easy to apply, and it gives a strong coating that lasts a few years at least. You can also use spar urethan for similar results. In some cases, you can wax wood to seal it, but this doesn’t give a particularly strong protective coating, so it will need to be reapplied very often if used on outdoor furniture.
4. Wood Oils
If you want to give your furniture a natural finish, you could try using wood oils. There are a number of different types available, most of them specific to the species of wood. For example, you need teak oil for teak furniture.
However, you can get general oils like Danish oil and tung oil that are good for several types of wood. Putting oil onto wood will protect it against moisture, give it a nice finish, and accentuate the grain of the wood.
The best type of oil to use depends on the type of wood and its condition. If the furniture is new and the wood has not been treated in the past, Danish oil, which is a thinner oil, works well. Tung oil is better if you want a strong, plastic-like finish that is closer to something like spar urethane or polycrylic but with a natural feel. It is not advised to use linseed oil for exterior projects as it does not offer adequate protection.
The oil needs to soak into the wood, so it cannot be used over the top of a wood stain like other sealants. The stain will prevent it from soaking in properly and you won’t get the protection that you need.
To apply wood oil, you will need to give the furniture a good clean first. You can use a brush, rag, or sprayer to apply it. The oil needs to be worked well into the wood, so make sure you take your time and don’t rush it. Once it’s applied, wipe away any excess that hasn’t soaked in.
Let it dry, give it a light sand, and then apply another coat. Two or three coats should be adequate. You can also get teak oil sprays which are great for topping up the coating without having to sand it beforehand.
One downside of wood oil is that it doesn’t last very long. The finish will start to wear off after a year or two, so you will need to reapply it. However, it is an easy process and the results are worth it if you want natural-looking furniture.
See our 10 best outdoor wood furniture wood oils in our detailed guide here.
5. Thompson’s Water Seal
Thompson’s Water Seal is a sealant that comes in a liquid form. It can be used on wood, concrete, and other materials. It is very easy to apply, it dries quickly, and you only need one coat on most pieces of furniture, so it’s a very popular option. You have a big range of colors to choose from too.
Even better, it lasts up to ten years without losing its color, so if you want a low-maintenance option, this is definitely the product for you.
Once you have cleaned the wood, the best way to apply Thompson’s Water Seal is with a sprayer. This cuts down the application time and gives you a nice even coverage. But if you don’t have one, you can still apply it easily with a brush, paint pad, or roller.
Alternative Ways to Protect Outdoor Wood Furniture
Sealing your wood furniture will protect it from moisture and prevent rotting. But you can make your furniture last even longer if you take additional steps to stop it from getting damaged. These are some of the easy things you can do.
Placing Wood Furniture Under Cover
Covering your wooden furniture is the simplest way to protect it. If you have a pergola or covered patio area of some kind, keep your furniture under there whenever you are not using it. Not only does this stop it from getting wet, but it also protects it from the sun, so the wood does not fade as easily.
Storing it During Winter Months
It’s unlikely that you spend much time sitting in the yard during the winter, so does your furniture need to stay out there? This is the time of year when it gets the most moisture exposure, so if you can store it in a garage or shed until the weather warms up, you will protect it.
Use a Furniture Cover
You may not have space to store it over the winter and you might not have a covered area in the garden either. In that case, invest in a furniture cover. This is a waterproof and weatherproof cover that will keep your furniture safe from the rain, snow, and sun. It’s not expensive and it’s a great way to protect wooden furniture without having to move it.
See our best outdoor furniture covers here!
Regular Cleaning
Even if you take all of the above steps to protect your furniture, it’s still important to clean it on a regular basis. This will remove any dirt, dust, or debris that can damage the wood over time. Small pieces of dirt can carry mildew spores and moisture onto the wood, increasing the chances of decay. Simply wiping it down and brushing away loose dirt on a regular basis can make a big difference.
Give your furniture a deep clean once or twice a year by using a wood cleaner. This will remove any built-up dirt or grease and it will also restore the natural color of the wood. It’s a good idea to do this in the spring and autumn when the weather is changing, as this is when your furniture is most at risk of damage.
Avoid Placing Directly in Grass and Soil
If you can, try to avoid placing your wooden furniture directly on the grass or in the soil. The moisture in the ground can cause the wood to rot and decay, so it’s best to use a patio or decking area instead. If you have no choice but to place it on the grass, then consider putting some feet on it to prevent moisture from soaking up through the bottom of the legs.
Do Some Types of Wood Require More Maintenance?
Different types of wood require different levels of maintenance. Cedar, for example, is a softer wood and it will decay more quickly than harder woods like oak or ash. If you want your furniture to last for many years, it’s important to choose the right type of wood and to give it the required amount of care.
Woods that require the least maintenance include teak, cypress, and mahogany. These woods are naturally resistant to moisture and decay, so you don’t have to do much to protect them. However, they will still benefit from a coat of sealant every now and then.
A lot of wooden furniture is pressure-treated with chemicals that give it some moisture resistance and protection from mold and mildew. This type of wood requires less maintenance too, but it should still be sealed regularly to increase its longevity.
Does the Sun Damage Outdoor Wood?
The sun can cause outdoor wood to fade and become brittle over time. The good news is, most waterproof sealers also provide strong UV protection to prevent this. When you are choosing products to seal outdoor furniture, always double-check that it protects against sun damage too.
Final Thoughts
Taking the time to properly care for your wooden furniture can make a big difference in its lifespan. Sealing it is the most important thing you can do because prolonged exposure to moisture and sunlight will do a lot of damage. All of the options outlined in this article will help you prevent decay and keep your outdoor furniture in great condition.
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.