Caulking to Reduce Infiltration
The purpose of caulking is to reduce the infiltration of air, dirt, noise, moisture, and insects into the home. Caulk is any pliable material that can be used to fill cracks and stop leaks. It is designed for areas where parts do not have to move relative to one another. Weather-stripping, on the other hand, is designed to stop air leakage in areas where parts must move, like doors and windows. Caulk is most commonly purchased in cartridges that require a caulk gun to apply, but also comes in convenient pressurized canisters, or in pre-formed rolls.
To begin a home weatherization project, examine your house for air leaks, inside and outside. Some leaks are hard to find because they are hidden behind cabinets or walls. If the home has a whole-house fan, it can help you locate leaks. Simply close up the house and turn the fan on. It will draw air out of the house, pulling air in through cracks. With the fan running, walk around the house and feel for leaks. You can use a piece of tissue paper or a feather to detect small air currents and movement. The professionals use smoke sticks.
The goal in sealing air leaks is to create an air-tight envelope around the living space. Begin on the inside, sealing every leak you can find.
Pay special attention to electrical outlets and switches. Walls are full of them and the plastic covers do little to stop air flow. Gaskets can be inserted behind the face plate and are available in hardware stores, and plastic inserts, which double as child-protection, can be inserted into the open plug openings. Also inside, areas under sinks and around doors, windows and vents should be examined carefully for leaks. Outside, look for cracks wherever two building sections meet or where dissimilar building materials come together, such as between the siding and the foundation or around windows and doors. Cracks are also likely where the building's shell has been pierced by pipe, wire, vents, or plumbing.
For cracks larger than one quarter inch, fill them first with fiberglass, or steel wool, or spray foam insulation, then apply caulk.