Staining Undersides of Deck Boards 5/5 (5)

This post was updated on January 19, 2022

How to Stain Undersides of Deck Boards

Welcome to Deckstainhelp.com, your source for the latest tips, tricks, deck stain industry insights. This is an update for our previously published article, discussing whether or not you should stain the underside of deck boards in 2020. We want to hear from you. Leave us a comment and tell us if you recommend staining the underside of deck boards, and why or why not.

Do You Need to Stain the Undersides of a Deck?

Bringing up some debate is whether or not you should stain the undersides of a deck. It is common and advisable to stain the weather-exposed surfaces of a deck to protect them from water and sun damage. But do the undersides of a deck also need to be protected?

Protecting the underside of a deck from the sun is not an issue since the underside of a deck is always shaded, but what about protection from moisture? Moisture is absorbed into unprotected wood causing it to swell. Once the wood dries out, it shrinks back to its normal size. Over time this constant swelling and shrinking cause deck boards to warp, crack, and split.

Obviously, the exposed upper side of a deck is much more susceptible to moisture and water damage caused by rain and even morning dew. Although the underside of a deck may get a little wet during a good downpour, it certainly is not as likely to get wet.

The dilemma with applying stain to the underside of a deck is time and the cost of doing it. In some instances, it is almost more work than it is worth. Staining the undersides of boards can be very labor-intensive and will double the stain cost of the deck-staining project.

There is also some debate about moisture being trapped if all sides of deck boards are stained. This varies by opinion but all boards should be able to breathe. Whatever the case, it seems that just staining only the top exposed surfaces of a deck makes the most sense.

One acceptable reason to stain the underside of a deck would be for appearance especially on an upper-level deck where the underside is more noticeable.

In the experience of most deck staining professionals, staining only the exposed surface of a deck is adequate in protecting the wood. If you want some of the beams, posts, or more exposed underneath portions of the deck stained strictly for appearance then that is up to you. But as far as protecting the wood, it is not necessary to stain the underside areas of a wood deck.

Please Ask Any Questions Below

Scott Paul ~ Restoring Wood & Decks Since 1993

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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