Redwood is so good at handling weather elements like sunlight and moisture that it can last for decades even without any type of treatment. Therefore, it is not surprising that most homeowners wonder whether it is worth sealing redwood siding.

While redwood is naturally durable, you should still seal it. This is because sealing it will prolong its lifespan. It will also make it easier for you to both maintain it and customize its appearance. And it can also help to keep the rich reddish color of the siding from fading.

Here is what you should know.

Should you seal Redwood siding

You should seal exterior redwood because it helps to prolong the life of your siding. It preserves its appearance, makes it easier to maintain, and also offers a perfect way to achieve a customized look.

Here is what you should know about why sealing the siding is always recommended.

Preserve color

You should seal your siding in order to keep its color from fading. It will keep it from turning soft gray by shielding it from weather elements. Therefore, if you want your siding to keep its rich color for a longer period, you should definitely consider sealing it.

Create a customized look

You should also seal the siding if you want to give it a customized look.

Doing so will give it a unique texture or hue that is designed to not only enhance your home’s curb appeal, but also make it stand out.

What is even better about using a sealer is that the look that you are gunning for doesn’t have to be radically different from that of the redwood. You can opt for sealants that simply enhance its appearance. This may mean having to go for transparent or semi-transparent sealers.

Easier maintenance

Sealants make it easier to refresh the look of siding. This is because all that one has to do in order to refresh the appearance of the siding is to simply reseal it. This is easy to do since what wears out is the sealant and not the wood surface.

Therefore, providing the wood surface with a fresh sealant coat will be enough to get rid of the weathered look. This is way easier and better than having to restore the appearance of the redwood.

Prolong its lifespan

While redwood is naturally more durable than other types of wood, it eventually wears out after constant exposure to moisture, sunlight, and other environmental elements.

Therefore, whether you are dealing with a redwood deck or siding, adding an extra layer of protection will always help in terms of improving durability. And that is what a good sealant will do: provide it with an extra layer of protection.

How do you seal redwood siding?

Sealing your siding, or even a redwood deck, is the best way to protect it. Here are the steps that you should follow if you want to prolong the lifespan of your siding.


Staining works well when the surface being stained is free of grime, dirt, debris, and oil. Therefore, cleaning your siding should be one of the first things that you should do.

If you have a pressure washer, you should definitely use it. It will make your work easier and you will end up saving a lot of time. This is because the pressure from the pressure washer will make it easier to dislodge stubborn dirt and debris from the surface, and this will in turn make the work of cleaning the siding to be less labor-intensive.


If the siding has been painted before, or if it has an old layer of stain, you will need to remove these layers before applying the stain.

Sanding is the best method of removing old paint or stains. It also smoothens the redwood surface, something that enhances the results. Therefore, right after the redwood surface properly dries up, you should sand it.

But if sanding is not effective, or if you simply don’t want to subject yourself to the physical demands of the sanding process, you can use chemical strippers. Provided you follow the instructions that they come with, using them will make for a less physically demanding process.


After sanding, you will need to get rid of any particles and dust that may be on the siding surface.

A tack cloth will come in handy in helping you do so. A good vacuum can also help. And so can a bucket of soapy water and a sponge. Using either method, right after removing old paint or staining, is thus advisable.


To apply the sealer, you will need a clean brush, fine-grit sandpaper, and a high-quality sealer.

Dip the brush in the sealer and then cover the siding surface with a thin coat. Use long strokes when working. And after you are done, give the first coat enough time to dry, sand it, and then apply a second coat.

When sealing redwood, there are a few things that you should keep in mind.

The first is that if you don’t have a brush, you can always use a rag — especially if you are dealing with something like a redwood deck — to apply the sealer or paint sprayer. The second is that you can always use multiple coats of sealants — as many as are needed to achieve the look and feel that you want.


These steps can work for any type of redwood structure or fixture. Therefore, whether you want to seal a redwood deck, your home’s siding, or any other item that is made out of redwood, the above steps will still apply.

Redwood color restoration

Both weathering and stains can change the color of redwood.

The good news is that you can always reverse these changes by cleaning the wood. If your siding changes color and you don’t like it, you can always reverse this change.

Here are the steps that you should follow for proper redwood color restoration.

Step 1: Clean your siding with water and a mild detergent

Over time, your siding will gather dust, grime, debris, and dirt. This will create ugly marks that will make your siding look unattractive.

If all you are dealing with is basic dirt and debris, then you won’t need much. A bucket of soap, clean water, and a detergent is all you will need to restore its appearance. Just wipe the siding down and then rinse it with clean water.

Step 1 Clean your siding with water and a mild detergent

Step 2: Scrub with a brush

However, if you are dealing with stubborn stains, rinsing with soapy water will not cut it. You will need to use a stiff-bristled brush. You may also need to use warm water.

The combination of warm water and scrubbing will help to dislodge any stubborn stains from the siding. Rinsing it off with a bucket of clean water, or with a hose, should then leave the siding free of any stains or debris.

Step 2 Scrub with a brush

Step 3: Rinse the siding with bleach

If the stains don’t come off, the next step is to conduct a mold and mildew test.

Perform this test by dabbing diluted bleach onto the stained surface. If the stains brighten up immediately, then you are likely dealing with severe mildew infestations.

Once you have confirmed that mildew and mold are to blame for the stains, start the removal process by scrubbing the affected area with a mild detergent.

Thereafter, dip a piece of cloth in diluted household bleach and then use it to wipe the area. Use a stiff bristle brush to dislodge any stubborn stains in the area. And after you are done, rinse the area with clean water.

Step 3 Rinse the siding with bleach

Step 4: Scrub the affected area with trisodium phosphate (TSP)

If your siding still has stains, you should mix a cup of household bleach, a cup of TSP, and a gallon of water. Use the resulting mix to wash the surface, and after you are done, rinse off the surface with clean water.

TSP is good at getting rid of extractive stains. It can also remove severe mildew stains.

Step 4 Scrub the affected area with trisodium phosphate (TSP)

Step 5: Apply a solution of oxalic acid

Oxalic acid is the most effective remover of stains that result from extractive bleeding. It also works wonders when it comes to removing iron stains.

Applying a solution of the acid will cause these stains to fade. And in about 20 minutes, it can completely clear any ugly marks that may have formed as a result of extractive bleeding and rusting.

For the best results, take oxalic acid — about 4 ounces — and mix it in a gallon of warm water. Take the resulting solution and then apply it to the stains. Give it time to work, and then rinse the area with clean water.

Step 4 Apply a solution of oxalic acid

What causes redwood discoloration?

Old redwood siding gradually loses color and becomes discolored because of a number of factors.

Here are the most common causes of wood siding discoloration.

  • Ultraviolet radiation
  • Extractive staining
  • Iron stains
  • Heat
  • Moisture
  • Soot

How to clean your siding

The steps that you are going to take in order to clean your siding will primarily be dictated by the cause of the stains and how stubborn they are. As a result, here are the general steps that a homeowner will have to take in order to get their siding to look great.

How to get rid of rust stains

With time, your siding will be exposed to moisture. The iron nails, and other fasteners, that are used to install it will eventually start to rust. The combination of the rust and redwood tannins will eventually form ugly stains that will then make the siding unattractive.

It is possible to restore your siding color by getting rid of these nail stains and any other stains that may form as a result of rust.

In order to get rid of rust stains from the wood surface, you will need the following.

  • Water
  • Oxalic acid crystals
  • A bristle brush

Here are the steps that you should follow.

  • Fill a cup with water
  • Add 4 ounces of oxalic acid to the water
  • Soak the stained area with the resulting solution
  • Use the brush to scrub the stains off the surface
  • Use clean water to rinse off the acid

How to get rid of extractive bleeding stains

Extractive bleeding is another common cause of stains in redwood.

To get rid of these stains, and to restore the natural color of your siding, you will need

  • A cup of TSP,
  • Oxalic acid crystals
  • Clean water
  • Household bleach.

The process

  • Start the process by washing the redwood with diluted bleach.
  • Thereafter, rinse the surface with water until there is no trace of the solution.
  • Mix a gallon of warm water with about 4 ounces of oxalic crystals ( Make sure that you do the mixing in a non-metallic container).
  • Apply the resulting solution to the siding
  • Give it enough time to dry, and then use clean water to rinse it off

How to get rid of mildew growth stains

Mold and mildew growth can also cause black, brown, white,e and dark spots on redwood. And if they are to blame, then you have to not only remove them, but also kill them.

To get rid of mildew stains, all you need to do is to wash the area with a mildew-killing solution. Commercial mildewcides can work. And so can diluted bleach. After you are done, simply rinse the area with clean water, and then let it dry.

Can you power wash wood siding?

You can clean your siding with a power washer.

This is an ideal way to clean siding because:

  • It saves time.
  • It is less labor-intensive, something that often leads to lower labor costs.
  • It tends to be more effective, than using a hose, at dislodging and washing away dirt and debris.

However, the power washing process has risks. It can wear out your siding. As a result, it is always advisable that you use the lowest pressure possible. This is in addition to directing the water jet at an angle.

Stain vs. Sealer

You can protect your siding by either staining or sealing it.

So, what is the difference between these two popular ways of treating wood siding?


The main difference between a stain and a sealer is the fact that stains are primarily designed to penetrate wood fibers while sealers are not. This penetration is what then allows stains to effectively seal the siding from moisture penetration.

When choosing stains, you will have to choose between transparent and semi-transparent stains.

Go for transparent stains when you have no intention of modifying the redwood color. But if you want to slightly enhance its color and give it more sunlight protection, then a semi-transparent stain will make more sense.

You can also get a more pigmented effect by using semi-solid or solid stains. With solid stains or semi-solid stains, you can be able to give your redwood more protection against the sun. However, you may not give it as much breathing room as may be desirable.


Sealants, on the other hand, do not penetrate wood fibers. They work by forming a protective layer on the wood’s surface and thereby shielding the wood from damage. Sealants can protect the wood from the sun, mildew, fungal infestations, and the harmful effects of moisture.

However, how much protection you get will largely depend on the additives that the sealant has. And so when choosing a sealant, it is always good to pay attention to which additives it has. Does it offer UV protection? Does it have fungicides or mildewcides? And how much-added protection does it offer?

Sealants are perfect in cases where you want to protect the wood without messing with its natural color. It is ideal mainly because it is clear, and so all it does is offer protection and enhance the appearance of the wood.

Ben McInerney
Author: Ben McInerney - is a qualified arborist with 15 plus years of industry experience in Arboriculture. He ran a successful tree service before turning to writing and publishing. Ben is dedicated to providing users with the most accurate up-to-date information on everything trees.