If you've decided that you want to change the look of your deck, one of the approaches that you can take is to add new post caps. Whether you remove the existing post caps or you perhaps don't have any post caps currently, new post caps will elevate the look of the structure. Regardless of the type of post caps that you buy, you'll need to determine the best way to mount them to your existing deck posts. Generally, there are several different methods that you can take, so you'll have the choice of what seems feasible for you based on your skills and available equipment. Here are three mounting options for post caps.
One of the simplest ways to install post caps on your deck posts is by caulking them into place. You'll need a tube of caulk and a caulking gun for this job. When you shop for caulk, make sure that it's rated for outdoor use and water-resistant, as this will prevent it from breaking down and allowing water to seep under your post caps. Generally, all that you'll need to do is apply a thin bead of caulk around the perimeter of the post and then slip the post cap on. Use a paper towel to wipe up any excess caulk for a clean look.
Another option for mounting your post caps is to use hardware. Screws are better than nails, although either type of hardware can work in this application. The specific series of steps that you take depends largely on the style of post caps that you're installing, so you'll want to check the instructions that come with your post caps. A common method is to push each post cap into place and then use screws or nails to join the post and the cap. You'll want to drive your nails or screw the screws from underneath, as this will hide them.
You may also be able to install your post caps simply by friction fit — that is, pressing the post caps onto the posts. If they're snug, you don't necessarily need to use another mounting method. Friction fit can be ideal if you're using post caps with lights in them. For example, if you'll need to eventually remove some of the post caps to change their bulbs, mounting them with a friction fit allows you to lift them up without much effort later on.
For more information, reach out to suppliers of things like 4x4 post caps.