Replacing skirting boards (base boards) is a fairly simple process and can be necessary if old skirting becomes discoloured or you'd simply prefer a refreshing look to your home with newer skirting. Also, when replacing floor tiles, the skirting should be removed first. With new carpet, new skirting should be installed first. Many different types of skirting exist in different widths, with many different types of wood, either painted or with the "natural wood" look.
Use a stud finder to locate the studs in the wall and mark off on the skirting where they are.
Push a flat nosed screwdriver down between the skirting and wall, as far as you can, at the stud. Pull the screwdriver away from the wall 1/2 inch, and with the screwdriver still in position, push about 2 inches of a small crowbar down between the wall and the screwdriver. The handle of the crowbar should be roughly 45 degrees to the wall.
Slowly push the handle toward the wall. This will leverage the skirting away from the wall. Repeat these steps at each stud to remove the skirting board.
Calculate the length of skirting needed, and add a few inches for cutting. Internal and external joint cuts are carried out when installing skirting: internal 45 degree cuts are carried out in the corner of a room, and external 45 degree cuts are carried out when a corner sticks out in a room (such as a cabinet or closet). In both cases, the skirting has to be cut in opposite ways to create a snug joint. Mark where the cut needs to be and cut using a mitre box and mitre saw.
Move from one joint to the next, methodically working on cutting until the section of skirting is finished. If cuts are not snug or to your liking, sanding the cut will make the joint tighter.
Place a stud finder on the wall and mark the wall with a pencil at each stud's location. If using nails, sink at least two nails into the skirting at each stud's location, making sure the nail head is sunk into the skirting. If using screws, one screw should be sufficient. Cover each nail hole with wood filler.
Caulk any possible gap between the top of the skirting and the wall. Wipe away any excess caulk, and be sure that no caulk is left on the skirting.
Work on one section (or wall) at a time. When two pieces of skirting have to be connected (example, halfway along a straight wall), a scarf joint needs to be cut. This joint comprises two parallel 45 degree cuts that will fit snugly together, held with adhesive glue. Though a power saw can be used, it's best to use a mitre box and mitre saw to create a good 45 degree joint. It is possible to use adhesive glue instead of screws or nails when connecting skirting to the wall, though both glue and nails/screws are preferable. Always be aware of whether you're cutting an internal or external 45 degree joint.