The End Seal Debate

There has been a long standing debate regarding the use of end seal and whether it is necessary to use it on the end cuts of hardwoods or not. The answer is a simple yes. Sure, it’s an easy task that you may be tempted to side step, thinking it’s not important, but continue reading why this extra step is vital to your deck’s stability as well as longevity.

Did you know that dry wood is naturally designed to look for, absorb, and store moisture? Here is a test that you can do at home to show just how much damage a small amount of water has the ability to make on a deck board whose end cut has no protection. Stand the unprotected cut end of a deck board in approximately 1 inch of standing water. Within 24 hours, the water will have risen up to 3 feet the length of the deck board.

Cut ends of deck boards are extremely susceptible to the absorption and evaporation of moisture. Remember, it’s the moisture content in deck boards that affect the amount of contraction and expansion of your deck boards. As we all know too well, this moisture content, if not planned for, can wreak havoc on an outdoor deck. When you cut your deck boards and leave the end cuts untreated, this leaves them vulnerable. This exposes the end grain which is where water enters a piece of wood most readily. The unrestricted water will give uneven moisture distribution, which ultimately causes cupping and severe end checking (cracks in the hardwood). No one wants that!

You may be asking how to prevent this. Almost all hardwood decking mills treat end cuts prior to shipping. That’s great, but what do you do when your deck boards aren’t the exact length you need? That’s easy; cut them yourself. BUT when you do cut your deck boards, coat your fresh end cuts immediately after cutting, with a wax based end seal product. This can be applied either with a rag or with a brush. I have found that folding a small rag and dipping into the wax end seal, then coating the end cuts works best for me. Note that when ripping boards, end grain seal is not required nor is it needed on the straight grain cuts; only on the end cuts.

When you are applying the end seal, use caution not to get the product on the surface of your deck boards. One draw-back to end grain seal is that it will stain your hardwood. If, by chance, you do get excess wax on the surface, it should be scraped off with a putty knife and lightly sanded in this area. If not taken care of, stain will not adhere to this area.

As you can see, unsealed end grain leads not only to checking, splitting, and cupping but incurs costly maintenance and repairs. When you build your deck, build it right the first time. Take the extra step and extra time to seal all end cuts. It will make a difference in the end.

Learn more about end grain sealer and why it's such a critical part of the deck building and installation process.