fillDecks can crack and split as the wood ages, leaving large voids on the surface, and it can be tempting to fill these voids with an outdoor wood filler. But as the Internet’s top authority on wood deck restoration, we do not recommend that you use wood filler or caulk for your decking projects. However, we are always interested in hearing about your experiences with deck restoration as well: If you’ve tried using wood crack filler on your deck or are thinking about doing so, feel free to leave us a comment or question below.