How to caulk the baseboards in your home When you change the baseboards in your home they will need to be caulked after they are installed to fill the gap between the baseboards and the wall. Put a line of painters tape along the top edge of the baseboard. Then put a second line of tape along the wall level with the top edge of the baseboard. Use a white caulk that you can paint to caulk the baseboard. Cut a diagonal piece off of the caulk tip and keep it small because you don't want a lot of excess caulk outside of the baseboard. Stop your bead of caulk short of the tapes end so that when you push the caulk into the groove with your finger and the caulk spreads out it won't go past the end of the tape. Once you've caulked the baseboard go back and pull the tape off and you will take the excess caulk off with the tape leaving a nice clean bead of caulk on the wall.