Deck sealers are important because they are necessary for protecting your deck against the elements. Building a deck can be a major investment for many, but it's also an investment in a part of your home that's almost always going to exposed to elements that can cause it damage. Rain, cold, and even sunlight can all wear away at the wood on your deck, and leaving it exposed for too long can cause the deck to rot. If you want to avoid seeing your investment literally fall to pieces, you'll definitely want to invest in a good deck sealer.