How to Patch a Leaking Roof From the Inside

Enter the attic and use the beam of a flashlight to locate the hole or crack in the roof that has leaked water in the past -- a puddle of water on the attic floor or on sections of the rafters will be an indicator of the location of the hole or crack.

Dry the areas where water has collected using paper towels. Apply heat from a heat gun to the crack or hole in the roof to thoroughly dry it out.

Apply roofing patch material to the edge of a metal putty knife. Fill the hole in the roof -- if there is a hole -- with the roofing patch material. Continue filling until the hole is completely filled. If there is a crack instead of a hole, ignore this step.

Place the edge of the putty knife that has the roofing patch material on it against one end of the crack or filled-in hole.

Press down on the edge of the putty knife as you drag it across the crack or filled-in hole. Remove the edge of the putty knife from the roof once you have reached the other side. Repeat this four additional times. Let the roofing patch material set for the amount of time specified in the instructions that accompany it.

Place the caulking cylinder into the caulking gun. Apply caulk, using the caulking gun, to the roof where the crack or hole is now covered in the same manner as was done with the roofing patch material -- but only the tip of the caulking gun should be pressed against the roof. Apply the caulking a total of five times.

Smooth the caulk on the roof with the edge of a wooden paint stir stick or the edge of the putty knife.