Cold air can come into your house through failed window glazing or caulking and make you uncomfortable in cold weather. If water can also get in, however, you may have to add the inconvenience of structural repairs to your discomfort. Fixing old caulk or glaze isn’t difficult, especially if the damage is obvious, but your task can be difficult if the leak is in the window frame or the siding. Water can penetrate through cracks and travel a long way before it begins dripping. That can frustrate your efforts to find the leak, much less repair it.
Chip off all the old window glazing with a putty knife. Do not remove the small triangular points that are keeping the window in place. Sand the frame by hand with 120-grit sandpaper, and wipe off the sanding dust with a rag.
Remove a quantity of glazing compound from the container, roll it around in your hands to make it pliable, and then form it into a rope. Lay the rope in the frame around the perimeter of the window, and push it into place.
Hold a putty knife parallel to one side of the frame with the blade at a 45-degree angle relative to the edge of the frame. Start at one corner, and draw the knife along the putty to create a flat surface that extends diagonally from the window to the edge of the frame. Repeat the procedure on the other three sides of the frame.
Let the putty harden for about 10 days, then coat it with oil-based wood primer. Paint the window when the primer dries.
Choose a dry day with moderate temperatures to recaulk leaking vinyl and metal windows with waterproof caulk. Pull off all peeling and loose caulk, and wash the window with a detergent solution to remove grease and oil that can prevent the caulk from adhering.
Put the tube of caulk into a caulking gun, cut the tip at a 45-degree angle with a utility knife, and puncture the seal with a 16d nail.
Lay a continuous bead with no voids or bubbles in the joint between the window and the frame along one side of the window. Tool the bead by running your finger along it, then caulk the other three sides of the window in the same way. Let the caulk cure overnight before you paint it.
Locate the leak, which may take some detective work. One strategy is to have someone spray a section of the window while you watch for leaks inside the house. You may have to remove some drywall from around the frame to see the leaks, because the water may be traveling along the wood after it enters.
Pry off the trim from the leaking area with a pry bar, and inspect the gap between the window and frame. You may be able to fill it with caulk. If you see rotten wood, chip it out with a putty knife, and fill the void with epoxy wood filler.
Check the trim and replace it if it is rotten. Nail it back to the window, and caulk all the edges with waterproof caulk. Let the caulk dry before repainting.