How to Transition Baseboards Across Different Floor Levels

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How to install baseboard molding where there are changes in floor heights.

There are occasions during home renovations where it is necessary to install baseboard trim across differing floor levels or elevations. This may occur where a new tile or hardwood floor is installed over an existing floor or to redo a poor finish carpentry installation. Either way with a few simple tips you can make this transition disappear or accentuate to show off you carpentry skills or the unique architecture of your home.

Types of Baseboard Transitions

Floor transitions fall into 3 basic forms; minor, intermediate, and large. Floor elevations that are under 1 inch would fall into the minor transitions; floor elevations that are over 1 inch but less than a full step height are intermediate; and step downs would be large transitions. Intermediate transitions are probably the rarest since a floor transition between 2 inches and 5 inches would be a trip hazard, but they can occur in older homes or around built-in cabinetry where the baseboard continues around the room.

Minor Transitions

If you have a minor transition between two adjoining floors, you have two options:

If the differential height is a small fraction of the baseboard height, such as ½-inch to ¾-inch, you can rip the bottom of the baseboard molding on a table saw to accommodate the height difference. This will produce a baseboard molding that is level along the top edge and create a continuous line across the floor transition. The issue with this method is that all of the baseboard moldings in the room will also require ripping to maintain a constant level. If there is a cased opening or doorway, you can stop the ripped baseboard at this point if you’d like. If there is an adjoining room, you can have different heights since there will be a door and casing molding creating a physical separation and a small height difference will not be noticeable.

Ripping the bottom edge of the baseboard

An alternate method would be to run the baseboard molding across the transition, leaving a gap between the bottom edge of the baseboard and the floor in the room where the floor is lower. After the baseboard has been installed, nail a filler strip that is the same thickness of your baseboard molding. Install quarter-round or shoe molding to cover the seam between the two pieces of wood. Where the quarter round meets the transition, you can cut the quarter round on an angle or chamfer the end to give it a more pleasing look.

Intermediate Transitions

For larger transitions, over ¾-inch, a good way to handle these situations is install an end block between the two pieces of baseboard. The end block can be ¾-inch stock, or ripped down to ½-inch. The bottom edge would be directly on top of the floor and the top edge would extend about ½ to ¾-in. above the top edge of the higher baseboard. The top edge can be cut on an angle or coped with a jigsaw or coping saw to mimic the top profile of the baseboard. The end block can be nailed into the end of the baseboard. The end block should be pre-drilled to prevent splitting.

Installing a block between two pieces of baseboard

Major Transitions

One of the easiest transitions to install is where there is a change in floor level near a step-down. In this case you install the baseboard to the step down then run the baseboard vertically to the next floor level, then continue baseboard along the other floor level. This is accomplished by cutting the end of the bottom piece of baseboard on a 45-degree angle, and then the vertical piece of baseboard has two 45-degree angles cut to resemble a parallelogram. The end of the other baseboard is cut with a matching 45-degree cut to continue the baseboard around the room.

Mitering baseboard to change floor levels

How to Install Baseboard Molding

1. Measure the length of each wall carefully to calculate how much molding you will need. Add about 15% to this total for waste.

2. Start installation at a convenient location. Cut baseboard to reach from corner to corner. For runs longer than 5 feet, cut the pieces about 1/16-inch longer than the measurement. You can bow the baseboard slightly to get it into place to form tight fit.

3. Drive 8 penny finishing nails into the studs and along the bottom plate of the wall. Use as many nails as needed to close any gaps between the molding and the wall.

4. Measure the next piece of baseboard from wall to wall and cut the end that will butt up against the first piece of baseboard on a 45-degree angle and then use this profile to cope the end.

5. After coping the end of the second piece, measure and cut it to length. Again, add about 1/16 inch to the length for a tight fit.

6. To miter outside corners, fit the coped end of the molding first and then mark the miter location with the piece in place. Keep in mind that corners are rarely perfectly square. You may need to adjust the miter angles slightly for a good fit. Make test cuts in scrap. If the joint is open at the front, use a block plane at the back of the joint to tighten the fit. Another way to change a miter angle slightly is to place a playing card or two between the miter saw fence and molding.

7. Install quarter round or shoe molding if desired.

8. Putty and paint trim.

See my other related articles here:

How to Use Different Types of Molding in Your Home

Trim and Paneling Ideas to Improve the Look of Your Home


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Posted on Jan 25, 2011
Jerry Walch
Posted on Jan 25, 2011