Things You\’ll Need
If you've just built or remodeled a set of wood stairs in your home, you will note there is some spacing where the stairs meet the wall behind them. This is going to be the case whether you've got plain steps that sit individually against the wall, or an enclosed staircases that has a straight line of trim running the whole span diagonally. Sealing that gap in caulk will keep dirt and debris from accumulating there, and will give the stairway a finished look.
Clean out the joints where the sides of the stairs meet the wall, using a piece of folded sandpaper to get the whole area free of loose plaster or dirt. Get the sandpaper well down into the joint. Blow away the dust as you sand.
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Put your tube of caulk into the caulk gun, setting the back end in first and then snapping in the front. Cut a diagonal hole in plastic tip off the end of the tube, making the hole about 1/4-inch wide.
Insert a 3-inch nail into the hole to break the seal inside. Compress the gun's trigger to push the caulk up and out the hole in the tip. Release the latch at the back end of the gun to stop the flow of caulk.
Press the tip of the tube against the joint at one end of the first stair where it meets the wall, at the highest point where it meets the wall. Hold the gun forward at a diagonal angle. Compress the trigger and begin pulling the gun slowly backward along the joint, creating a thin, smooth line of caulk.
Continue to the end of the joint. Release the latch at the back end of the gun to stop the caulk flow while lifting the tip off the joint.
Repeat for each joint between the stairs and the wall.