Caulking your home exterior can prevent heat loss during the winter and keep cooler air indoors during the summer, according to the U.S. Department of Energy. This can help reduce your energy expenses. This flexible seal compound -- available in a caulking gun or pressurized cartridge applicator -- has to be applied thoroughly to cracks or gaps between your indoor and outdoor surfaces. This also includes the joints between stucco walls and your trim.
Four caulking types exist: rubber, latex, silicone and polyurethane. Of these, polyurethane caulk sealant is typically used on concrete and masonry walls, making it a good choice for stucco, which is comprised of cement. The price can vary between $3.50 to $7.50, according to This Old House. Polyurethane caulk is used around the exterior of windows and doors, to repair cracked masonry -- such as stucco -- and to seal joints (for example, joints of window trim being attached to stucco walls).
You need to caulk between your stucco and trim to prevent moisture from getting between the two building materials. Otherwise you will experience rot and decay problems, especially if you have wood beneath your stucco. According to Prime Stucco, you need to caulk between all joined trim moldings in addition to caulking between your home molding trim and the particular base material used, such as stucco or wood. You also need to cover all your trim joints with caulking.
In addition to your doors and windows, you need to caulk between all home trim and attachments to prevent moisture and energy loss. This includes electrical penetrations such as outdoor light fixtures, cable TV boxes and other receptacles attached to your home. It also includes dryer vents, fireplace termination caps and plumbing penetrations such as sillcocks, according to the building codes of Johnson County Kansas Unincorporated.
Temperature plays a role in how successful your caulking efforts will be with your stucco and trim. Don't caulk your exterior wall and trim if the temperature if below 40 degrees Fahrenheit outdoors. Don't leave your caulk outdoors in that temperature before use either. And don't attempt to caulk surfaces that are not clean and thoroughly dry, or which contain grease, paint or oil on them. Remove all prior caulk before caulking a surface for the second time. Polyurethane caulk sealants can become messy if you over apply them, becoming hard to tool.