Gluing your shiplap is not absolutely necessary. If you are installing shiplap horizontally, you want to find the studs in your walls with a stud finder and add your nails there. However, if you are installing the shiplap vertically, it can be trickier because not every slat would line up with a stud. For this reason, we recommend using a high-quality construction adhesive for vertical shiplap in addition to nails (or staples, as we used on this vertical shiplap wall).