Stain Underside of Deck Board?  4.9/5 (112)

This post was updated on April 22, 2024

Do You Stain All Sides of Deck Board?

Welcome to Deckstainhelp.com, your source for the latest tips, tricks, and deck stain industry insights. This is an update for our previously published article, discussing whether or not you should stain all sides of the deck board. As before, we recommend you only stain the exposed sides of the deck board. We want to hear from you. Leave us a comment below.


Stain All Sides of Boards or Just Exposed Sides?

A common question when it comes to staining a wood deck is whether or not you have to stain all the sides of the deck boards including underneath.

Normally a deck floor is only stained on the exposed side facing up. This helps protect the boards from UV fading and water damage. The underside of a deck obviously is not going to be subjected to any harsh UV rays but what about moisture?

Moisture and water damage can be a problem, especially on the exposed side of a deck where rain constantly hits the boards and may even puddle up allowing it to be absorbed. On the underside of a deck, the boards are not being pelted with rain but they can get slightly wet during a good downpour. The problem with staining deck boards underneath is that it is almost more trouble than it is worth.

Stain Undersides of Deck

Unless you are staining all the sides of each board as the deck is being built, staining the underside of an existing deck can be very labor-intensive, time-consuming, and expensive. In addition, some areas of the underneath boards will still not be stained. Anywhere a deck board rides above or comes in contact with a support beam or floor joist you can’t even see, let alone stain.

There has also been some debate as to whether or not staining all sides of deck boards can actually trap moisture. There are various opinions about this but all boards by nature have moisture in them and should be able to breathe. So it makes the most sense to stain only the top exposed portions of a deck board where it is prone to sun and rain damage.

One reason you may want to stain all sides of deck boards is for aesthetic purposes, especially on an upper-level deck. When the underside of an upper-level deck is exposed it can be more of an appearance issue when concerning yourself with staining the bottom side of a deck.

In our experience, staining only the exposed sides of deck boards is sufficient for protecting the wood from heavy traffic and weather. It is common however to stain the underside of any deck steps, exposed beams, and supports they may be more noticeable. In some cases, if a deck owner is willing to do the work or pay for it, staining the underside of deck boards, especially on elevated decks is more personal preference than anything and certainly is not necessary.

Question on Staining All Sides of Deck Boards? Please Ask Below

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Scott Paul ~ Restoring Wood & Decks Since 1993 Owner
As an article and comment contributor to the site, Scott has been around the pressure washing industry since attending college. In 1993 he started his first company called Oakland Pressure Wash specializing in exterior pressure washing and deck staining. That company evolved into OPW L.L.C. shortly thereafter concentrating more on exterior wood and deck restoration. Scott and his Deck Cleaning Michigan company have restored over 10,000 decks in the Metro Detroit area since the early years. He has become an authority in the deck restoration industry and has contributed to numerous wood restoration forums and informative sites. All the products he suggests through this site are sold through online sites and in retail stores, allowing the consumer to choose their own means of purchase. Scott’s eCommerce sites do sell many top brands he endorses and if you appreciate any of the help he has offered then feel free to purchase from one of them.

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RichC
RichC
1 month ago

I have a gray TimberTech deck with a paving stone patio underneath. Rain drips and stains the paving stones & over time seems to discolor my patio. Should I paint or maybe stain the under side of my deck to block the staining problem? Or is there any solution to keep my patio looking good? Thank you.

Mike Rohling
Mike Rohling
1 year ago

I will be staining all deck boards with exception of underneath deck with oil based semi solid stain. My research shows a water based sealer on top of the oil based stain is ok with a little preparation of wiping down all boards with water/denatured alcohol solution of 1:1 is recommended. Is this correct?
Is there a significant benefit of applying a sealer on top of a stain?

Googe
Googe
2 years ago

Replacing the rotten joists and rotten top boards of my 31 yo redwood deck. I live in No. California where oak leaves are an issue. Was thinking that I would paint the top of the new 2×10 joists with latex paint to give them some protection before we put the new redwood on top. Would this be ok?

Vladimir jozic
Vladimir jozic
3 years ago

As I’m decking over concreate the rain will sit on the concreate as the concreate has a slight fall should I put a clear coat on both sides of timber decking to prevent water and mould growth from the under side thank you

Jared
Jared
4 years ago

From the midwest USA – we have giant bees drilling into the underside of our second-story deck, so I used a S.W. clear sealer on the underside to take away the bare, untreated wood that bees look for. It was not THAT labor intensive, just a lot of holding your hands above your head. I used a light coat on the underside of the deck boards, a regular coat on the frame.
Are there any completed studies about using a clear sealer/water treatment around the entire board? I am trying to decide what to do on the stairs, I need to take up every deck board and sand, because it is 10 years old and never really treated for the weather. I am planning to do a light coat on the bottom, mostly because the rain water hugs wood and drips from the underside.

James
James
3 years ago
Reply to  Jared

Quick comment. Those bees are “carpenter bees”, and they prefer bare wood. A stain will make the wood less attractive to the carpenter bees.

The article above does say staining the underside of boards that are more noticable (like steps or underside of 2 story deck) is more of a personal preference.

Brent Fadum
Brent Fadum
4 years ago

Should I make a real effort to stain the sides of deck boards (between boards) on a deck that is already built, or just get as much as reasonably possibly without spending a lot of time?

Shelly
Shelly
4 years ago

Should I stain my cedar deck or can I leave it to weather? Will the boards get slivery if I do not? Will staining make it last longer? 🙂

Shelly
Shelly
4 years ago

Is there any advantage to staining a cedar deck? Will it last at look good if I leave it to weather? I live in Edmonton Alberta Canada and we get up to 40C below.

Queena
Queena
5 years ago

I have a 5.6 foot high cedar deck that are enclosed by pressure treated wood fence boards forming a shack. Summer 2017 I applied one coat of Thompson Water Seal (Clear) to the topside of the deck and outside vertical fence boards. This week I notice the underside of the cedar deck crawling with springtails, apparently a species that love moisture and damp areas. Does staining the underside of the cedar deck get rid of moisture and dampness? Or could I be trapping moisture and dampness by staining the underside of cedar deck and make the situation worse?

And if yes, I need to stain the underside of cedar deck, my second question is, should I use Thompson Water Seal (Clear) or should I use another product that can breathe? And what does it mean that the stain for underside of a deck should breathe? Any experience with this issue and how it was solved I greatly appreciate.

Last question, is it the case that for all cedar decks, both topside and underside of deck boards require staining? I get conflicting answers from experts at deck stores.

Richard
Richard
5 years ago

I have a 2nd story deck and a patio below. Can I put a solid stain or seal the deck posts supporting the deck or do I need to use a breathable stain? As mentioned above I am worried it will trap excess moisture and facilitate in its deterioration.
Thanks!

Sid
Sid
6 years ago

I have two decks levels (lanais) wrapping around my Waimea home. One deck over the other. The top side of the upper deck is stained a dark brown. The underside of the top deck is stained white which can be seen from the lower deck. The top side of the upper deck needs to be restained, but the white stained planks of the under side (which can be seen when looking up from the lower deck) does NOT need to be restained. It’s well protected from the sun and harsher weather elements.

Question: I have no problem protecting the lower level level deck by putting a tarp over it, but how do I stop the dark stain from dripping through gaps in the planks on the upper deck and making a mess of the white stained underside of that top deck?

I don’t want to change the color of the white underside, I want to preserve its great look without dark brown stain drips, drabs and smears getting all over it.

Any suggestions?

Mahalo from The Big Island!

Kelli
Kelli
6 years ago

Hello,
I’ve got a 3 story home in the Florida keys with exposed decking going around the entire house on the upper two floors including , four stair cases.
I’m changing all my exposed decking materials to Tangent technologies pvc/ plastic materials but the ledger boards, rim joists and floor joists are exposed and have a very unsightly appearance from the ground looking up.
I ve read that staining or painting these boards isn’t necessary and that boards need to breath for expansion and contraction.
My boards are 32 years old.
Will I create any negative issues for myself if I stain or paint my existing boards all the way around other than cost and labor.
Do my existing boards still need to breath if there years old.
I really don’t like the naturally aged look of the decks and am willing to pay the costs associated to get the appearance of a newer home.
Thanks so much.
Kelli

Rick Siu
Rick Siu
6 years ago

I am replacing a deck that is on the second story with all new cedar boards. I have the opportunity to stain the underside and sides of the deck boards before assembly, but I have also heard that you should let your deck weather for a bit before staining. Should I stain the wood prior to assembly, which would get all sides, or build it and let it weather for a bit before staining? Thanks

Myles Harmer
Myles Harmer
6 years ago

I am building a deck less than two feet from the ground. I can stain the red cedar before installation so I was wondering if it is better to stain all sides of the wood prior to installation. I am going to use Sikkens Srd. to stain the cedar. I live in Canada so extreme winter conditions are normal. Any help would be appreciated. Thank you Myles.

DIANE ERICSSON
DIANE ERICSSON
7 years ago

Redwood deck that we have needs staining again. We do this about every 4 to 5 years. We are getting older and want to roll the stain on. We can't get it onto the sides of the boards. How can we do this? Is there a "roller" that has something on it to get in between the boards. Or deck is just over 25 years old.
Thanks

Mike
Mike
7 years ago

We are removing sickens from our deck and staining with a penetrating stain. Should we remove the previous coatings from all sides?

Dean Bennett
Dean Bennett
8 years ago

I am replacing the top of the wood deck with cedar, and removing the treated wood. We will be staining with a transparent product. Would it be a good idea to stain the framework of the deck(treated and has been several years}, as long as it is all now exposed. This would be to just protect it again from the agents of rain and snow, or moisture in general.

Steve
Steve
8 years ago

Our deck is elevated about 12'. I don't mind putting in the time if will extend the life of the deck. So is your rec time investment based or won't it extend enough to make it worthwhile.

Morgan
Morgan
8 years ago

Is your recommendation the same for a deck that is only about 2 ft off the ground. Our deck sits at the bottom of a slop against our house and is in the drainage path for our yard, so there is sometimes moisture on the ground. We were considering whether to seal the bottom of the boards before install. Thanks for any insight.

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