Wood Filler for Decks 4.5/5 (21)

by Deck Stain Help

Updated February 2020

Use a Wood Filler for Decks?

DeckStainHelp.com has become the Internet’s number one resource for all things wood deck restoration related. As before, we do not recommend you use wood or crack filler and/or caulk for your decking projects. Feel free to leave us a comment with pictures of your completed projects below.


Best Wood Filler and Caulk for Decks

When taking on an exterior wood maintenance project, it is always best to follow proven methods to get the best results. For the do-it-yourself enthusiast, restoring a wood deck or other wood surface is something you can accomplish in a few days. Being educated on wood restoration will ensure your wood surface will look good and last for many years.

Many homeowners have asked about using wood filler and/or caulk prior to staining. As wood ages, it can crack and split leaving large voids on the surface. It can be tempting to fill these voids with a wood filler or caulk. Experts say that this can actually be a mistake you may want to avoid at all costs.

Wood filler and caulk do not work well for decking. There are several reasons for this. The wood filler does not “stain” to match the deck finish. This can be frustrating for someone staining a deck. No matter how hard you try, the caulk will not look like the rest of the stained surface and will stick out like a sore thumb.

Another major issue with using wood filler on a deck or wood surface is the stability of the filler. Wood filler and caulk are not stable and end up cracking or breaking out of the voids. This is especially true in an area where there is a wide range of climate change. Colder climates that freeze and thaw will cause wood filler and caulk to fail quickly.

Wood Deck Crack Fillers

Trying to use wood filler or caulk prior to staining will just end up looking unsightly, as the product will eventually fail anyway. The best way to deal with cracks and voids is to sand around the area to lessen the size of the crack. In extreme cases, replacing the boards or turning them over may be the best option. Otherwise, some small cracks and splits will not hurt the deck’s performance and can be stained over.

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Kevin
Kevin

What do you recommend for a knot that has started to rot? I see you don’t recommend fillers but worried to just stain this area like the rest of the deck.

Any help would be greatly appreciated!

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Rox
Rox

What stainable product would you use to fill cracks on a deck in Maine that is exposed to extreme heat & cold?

Judie
Judie

The top rail in this photo has been curing for 8 months and we are now ready to stain deck- photos show what happened to board over winter. If filler is not suggested, do you have any suggestions as to what should be done? Thanks for your time and great website!

Jeff
Jeff

my contractor filled screw holes on the deck and railing with wood filler then sanded the areas. I wanted to stain it natural, but now not sure what to do as I’m concerned these wood fill sections will be very noticeable. Should I sand the whole deck and railing to even it out then prep treat it before I stain? Would changing the stain color to a darker shade help?

Tresa Litteral
Tresa Litteral

Building a new deck. Should anything be done to the knots in the wood before staining deck?

Larry
Larry

Hello,

We have an old (likely since the house was built in 1990) untreated cedar deck, with some rot and/or softer spots on its boards.
1.) Would I be able to use PC-Petrifier Wood Hardener on some of its boards and railings? (I wouldn’t mind using on all of it.)
2.) If so, should I use it after I would clean and brighten it?
3.) I’d like to just seal it afterwards (and yearly from now on). What would you recommend as the best sealer for this type (age & condition) of deck? We live in Seattle, and even though the deck is facing west, it gets max 3hrs/day of sunlight.

Thank you very much!
Larry

glenn r grossarth
glenn r grossarth

I just put new decking boards on my deck, Looks really good but a lot of nail holes, I would like to fill them and stain the deck clear, question is there any filler that would look like treated wood ? so when I put the thompsons clear on my eyes won’t go right to them ? Thanks Glenn

Mark
Mark

I know that wood filler and caulk aren’t good options for filling cracks on deck but, I have a toddler and I’m concerned about splinters. My deck was in bad shape when we moved to this house and I have sanded it down so it’s a flush surface again. I still have cracks and some deep chips. If I just paint my deck is there anything I could use to fill the bad areas? I would replace some of the boards but it would end up being more than half the deck and I can’t get into that big of a project. Please any help you can offer would be greatly appreciated