How To Make Floor Transition Strips Between Two Uneven Floors

Tile, carpet and hardwood are rarely the same thickness. When two of them meet at a doorway, the abrupt edge is obvious. It might be slight, or enough to stub your toe. Transition strips create a bridge to fill the uneven gap. One size doesn't fit all, so the solution is to make your own with hardwood.

Commercial floor installers deal with differing floor heights with different techniques. Some build a ramp under the shorter surface, and skip the transition strip — but ramps break down over time. Some use aluminum or metal transition strips, but they look industrial.

A wood transition strip allows you the flexibility to custom-fit the transition strip if needed. The natural warmth and durability of hardwood adds a homey touch to flooring.

Don't confuse a transition strip with an overlap reducer, which is used for dramatic drop-offs between floors. It looks like a short, blunt ramp with a single lip.

T-molding transition strips have two lips to cover the edges of both surfaces, when flooring products differ no more than about 3/8-inch in height. Transition strips do not bottom out; the leg of the "T" doesn't touch the floor. The strip is supported on both sides by the lips, and held in place with nails.

T-molding is created by cutting a rabbet on both sides of a piece of hardwood. It's best to cut the rabbets first, and then route or sand the profile on top. The square shape of the hardwood — before it's rounded — makes it easier to work with.

Transition molding requires at least a 3/8-inch gap between the vertical bottom of the "T" shape and the flooring on each side. The gap, also known as an expansion gap, allows floors to expand as needed. The molding is nailed to the subfloor — never to flooring products.

Cutting rabbets for a transition strip is a basic woodworking technique. There are several ways to accomplish it, including a router or table saw with a dado blade, but one of the most convenient methods employs a table saw with a standard blade. Make a 48-inch transition strip long enough to span most doorways.

1. Set Blade Height

Raise the blade on a table saw to 3/4 inch, from the point where it emerges from the table to the tip of the highest tooth.

2. Set the Fence

Set the table saw fence at 5/16-inch. Lock it down.

3. Cut the Kerf

Stand the oak on edge, behind the blade. Turn on the saw and run the oak over the blade. Flip the oak 180 degrees. Cut a matching kerf on the opposite side. The kerf is slot or channel in the wood that the blade creates.

4. Set Blade and Fence

Raise the blade on the table saw to 1/4 inch. Set the fence at 5/8 inch.

5. Cut the Rabbets

Lay the molding flat behind the blade, with the kerfs on the bottom. Run the molding over the blade to cut a 1/4-by-3/4-inch rabbet. Flip it 180 degrees and make an identical cut on the opposite side to create the "T" shape.

6. Add Support Blocking

Place a 1/4-by-3/4-by-72-inch piece of scrap wood on the edge of a table. Place clamps on both ends. This piece serves as a support for the T-shaped molding so you can add the rounded profile.

7. Shape the Profile

Fit the lip of the T-molding over the scrap wood, facing the edge of the table. The curvature of the lip is a matter of personal choice. Use an orbital sander with 100-grit sandpaper to round it lightly. Use a belt sander with 100-grit belt to round it to a higher degree. Use a router with a 1/4-inch roundover bit to round it significantly.

8. Sand and Finish

Sand the molding smooth by hand with 100-grit sandpaper. Add stain and lacquer as needed.

9. Cut and Install

Measure the length of the transition. Use a miter saw to cut it to length. Fit it into the gap. Use 2-inch finish nails and hammer to secure it to the subfloor. Do not nail it to the flooring products.

Don't be afraid to customize your transition strips. If you have only slight differences in height, cut the rabbets shallow. If you have a drastic difference in height, use thicker material, and cut the rabbets deeper, or cut one deep, and one shallow. If you have only a shallow gap side to side, cut the T-shaped leg more narrow.