Should I 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.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 in 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.
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