what can caulk be used for
For outdoor applications, select caulk rated for exterior use. Most often these will be either silicone-based or an acrylic blend with silicone added. Image 1 shows three varieties of caulk including: tub and tile; paintable acrylic blend window, door and molding; and silicone window, door and molding. Although it can be tempting, caulk shouldn't be used as a filler. For gaps larger than 1/4 inch, you'll need to use a spray foam or backer rod to fill larger gaps, and then follow up with caulk. Backer rod is usually found with weather stripping.