Using a Wood Filler For Decks is Tricky!! Read this first…

May 18, 2023
Deck Restoration | By Jason Rowe
Wood Filler For Decks

If you’re looking for the best wood filler for decks then this article will be the most important thing you read all day…

Here’s the thing…

I’ve been sanding and staining decks for over 8 years now and I’ve never seen a time where applying wood filler to an outdoor deck for any type of repair has ever lasted long term…

That’s why I don’t recommend filling deck cracks with a wood filler…

There’s a couple of reasons for this that I’ll go into now…

Why I don’t recommend using a wood filler for decks…

Do you see how your deck boards are all cracked and split?

Well that’s obviously from being exposed to the harsh weather right?

What happens is, the rain soaks your deck boards and then the sun comes and dries them out again…

This soaking and drying causes your boards to expand and then contract…

Expand and contract…

Over and over again…

Sometimes if the spacing between the decking boards is too close, when the boards expand with the rain, the boards next to each other will touch…

And this can cause the boards to warp and buckle…

As you could imagine, with this constant weathering, your deck boards will start to crack and split…

So now, if you fill those deck cracks with a wood filler, the expanding and contracting of the wood doesn’t stop…

The wood filler is hard and can’t expand and contract with the timber so the wood filler will just crack and fall out…

And the biggest problem with the wood filler cracking and falling out is not that it looks ugly…

You could use a more flexible epoxy but it looks ugly under the stain or deck oil…

Now, the biggest problem with this is that the areas where the filler comes out from are now left bare and exposed to the weather…

So the damage will get worse on your deck and your boards will eventually rot out and need to be replaced…

It’s a waste of time and money to be filling cracks in your deck boards…

Let me show you something…

See this deck brush applicator?

The bristles stain inside deck cracks
Deck applicator for deck cracks

When you apply a quality stain or deck oil to your boards, those bristles will work their way in between the boards and also coat the sides of the boards…

Make sense?

Ok, so with this in mind, these bristles will also get inside any cracks in your deck boards and give them a coat of oil as well…

This doesn’t completely protect the cracked sections but coatinging the inside of the cracks will greatly reduce the effects of the weather so your deck boards will last a lot longer before they’ll need to be replaced…

But, if you fill those cracks with a wood filler, the deck oils and stains can’t coat and protect inside those cracks…

Then a few months later when the wood filler falls out, those boards will be completely exposed…

And trust me when I say, that wood filler is coming out…

That’s why I don’t recommend any type of wood filler for deck cracks…

But I also know that some people won’t care what the deck looks like in 2 to 12 months because perhaps you’re trying to sell your home…

Or maybe you don’t mind re-doing the filler every 6 to12 months…

In that case, if you are going to fill your deck cracks with a filler, here’s what you should look for…

Hey! Do you have a question?

I know you’re busy reading all about the horrors of using wood filler on your deck, but if there’s something you’re struggling to find answers for, why don’t you just ask me?

Yep, I can be your personal deck consultant…

Tips For Choosing the Best Wood Filler For Deck Cracks…

By now you know that I don’t like filling decking boards with a wood filler but sometimes it’s what the customer really wants…

So when I do fill in those cracks, here’s what I look for in a wood filler…

  1. Look for a wood filler made by the company that made your deck coating…
  2. Be sure it’s for exterior use…
  3. Make sure it takes on the colour of the stain…

Look for a wood filler made by the company that made your deck coating…

When I do a deck restoration, a lot of the time I use Intergrain decking oil or Cabot’s deck stain…

The great thing with Intergrain and Cabot’s is that they also have a range of exterior wood filler that are made specifically for outdoor decks…

And they have a different colour of wood filler to match the different colours of stain…

So when I have to fill cracks in the decking boards, I always check to see if the company that makes the stain also has a wood filler…

They would’ve tested the filler to make sure it works well with the stain…

That’s why this is my number one time when selecting a wood filler…

Be sure it’s for exterior use…

When choosing a wood filler, the number one thing to look for is to make sure it’s for exterior use…

If you choose a wood filler that’s designed for interior use, it’ll fail out a lot sooner than an exterior wood filler…

An interior wood filler isn’t as flexible as an exterior filler and it can’t withstand the UV from the sun…

The sun will cause it to shrink and dry out…

So make sure you use a filler that has “Exterior Use” printed on the side…

Moving on…

Make sure it takes on the colour of the stain…

Some deck fillers that you use, won’t take on the colour of the stain so it won’t blend into the rest of your deck…

The whole idea is to make the gaps disappear, not highlight them with an ugly filler that stands out through the deck stain…

That’s another reason why I recommend getting a wood filler from the same company that produces your deck stain…

They’ve already gone to the trouble of colour matching the wood fillers to the stain…

With that said, most exterior fillers will have different colours to choose from…

You just need to make sure you choose one that will look similar to the finished colour you want…

And also check the packaging to see if it is designed to absorb stain and take on that colour…

You just need to read the package…

The 2 Wood Fillers That I Recommend for Decks…

  1. Intergrain WoodBlend
  2. Cabot’s Wood Tone Putty

These 2 could be the perfect wood filler for decks…

They’re made by the deck stain companies so they will work better with decking stain…

Let’s have a closer look at both of them…

1. Intergrain WoodBlend…

I did previously introduce you to the filler that I use on decks but just in case you missed it…

One of the best wood fillers for decks would have to be the Intergrain Wood Filler…

Intergrain WoodBlend is a great wood filler for decks…

This product comes in 6 different colours…

  1. Cyprus/Cedar
  2. Ash/Meranti
  3. Radiata/Baltic
  4. Teak/Blackwood
  5. Walnut/Dark Oak
  6. Jarrah/Merbau

With this range, you’ll be able to find a colour that suits your timber and stain…

It’s pretty easy to use…

You can mix a little water with the putty and then work it into the cracks…

The great thing is that it’s pretty easy to sand smooth and it has been designed by a deck stain company to be used with deck stain…

So it will take on the colour of the stain much better than some other exterior wood fillers…

2. Cabot’s Wood Tone Putty

Cabot’s Wood Tone Putty is another wood filler that I’ve used on decks in the past…

Cabot’s Wood Tone Putty is a wood filler designed for decks

This filler also comes in 5 colours…

  1. Cedarstone
  2. Meranti
  3. Natural
  4. Pine
  5. Walnut

You apply the filler in the same way as any other wood filler…

You know…

Slap some putty into the cracks and spread it around…

Ok, how about I list it out step by step so there’s no confusion…

How to Fill Gaps in a Wood Deck…

Filling the gaps in your wood deck is pretty easy to do…

Each product will have its own instructions but this is generally how you would do it…

  1. Use a flexible blade or scraper to apply the filler to deck cracks.
  2. If the hole is deep, make sure to only fill in 10mm stages and allow 2 hours to dry.
  3. You can slightly wet the blade to make it easier to work the filler into the cracks.
  4. To fill thin timber grain, reduce filler with water.
  5. Smooth filler with the damp blade and remove any excess with a sponge.
  6. Allow to dry and then sand smooth.

It’s not rocket science…

Believe me when I say, “You can do this”…

So I wouldn’t freak out over filling the crack in your deck

Some other tips for using a wood filler on your deck…

Most of the fillers you get will look terrible when coated with a transparent or semi transparent stain…

Not always, but most times…

So if you are looking to fill those deck cracks, then it will look better if you use an opaque deck stain that will completely cover and hide the filler…

That’s the first thing to consider…

Next, you need to realise that usually if you fill the cracks on a high-traffic deck, the filler could crack and fall out within a few months…

Usually!!

So with all that said, there will be cases where a filler will last 12 months…

But, all of the decks that I restored that have previously been filled…

The owner has said they would never do that again because it didn’t last very long at all…

It’s a waste of time and money…

Outdoor timber cracks and splits…

Alway has, always will…

In the same way that decking stains fade and will need to be re-done

So as long as you are aware that filling your deck crack with a wood filler is an ongoing maintenance process, and you’re willing to do it every 6 months…

Or every 12 to 18 months…

Then by all means, fill those cracks…

With all that said…

That’s all I’ve got for you today…

I think I’ll leave it right there…

Good luck with choosing a wood filler for decks…

I hope it all works out for you…

Peace,

Jason…

Need some Expert Advice?

I’ve got 10 years of deck knowledge crammed into my noggin. I can pretty much guarantee I’ve got an answer to your problem just rattling around in there…

FAQ’s

Can wood filler be used on a deck?

Wood filler can be used to repair a deck but I don’t recommend it. Between the weather and the foot traffic on the deck, the filler will crack and fall out…

What is the best outdoor wood filler for decks?

The best outdoor wood filler for decks would be an exterior filler that is easy to sand and can be painted or stained…

Can you use wood filler on a decking without sanding?

No you can’t use a filler on a decking without sanding it back. If you do, the deck will be rough and the stain will peel from those sections very easily…

Summary
Using a Wood Filler For Decks is Tricky!! Read this first…
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Using a Wood Filler For Decks is Tricky!! Read this first…
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If you‘re looking for a wood filler for decks, then this article is a “must read” before you purchase any wood filler…
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The Deck Restoration Co.
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