A successful hardwood floor transition requires one of two different joints in order to change the direction of the planks. A change in direction refers to the positioning of the tongue and groove joints between each adjacent plank. While in the first room, the grooves on each plank might point away from the door, a transition allows that direction to change and the grooves to point the opposite way. Flooring transition is necessary where two rooms meet that both have hardwood floors. Your options are to use a T-molding, which creates a lip that sticks out between the planks at the transition point or a spline which is completely concealed.
Step 1: Lay Flooring Up to Transition Point
Joining two rooms with hardwood floors requires a transition point between them in the plane of the doorway. The transition lets you change the direction of the tongue and groove planks. Finish the first room with the planks laid with their tongues pointed away from the door. When you reach the door jamb, you should see a single groove from the last plank of hardwood you installed. Into this groove will go the spline, and from there the transition.
Step 2: Cut the Spline
The exact dimensions of the spline will depend upon the thickness of the groove in the plank. It will also depend upon the total depth of the grooves in each plank joined groove to groove. 5/16 of an inch is a common groove thickness, while a ½-inch space between is typical. Take the measurements and cut the spline to the necessary thickness and width.
Step 3: Cut Spline to Length
Now measure the length that the spline must be. It should extend the full length of the exposed groove. Mark it and cut it to the appropriate length with the circular saw.
Step 4: Sand the Edges
Round the edges of the spline until it resembles a rough oval. It need not be exactly that shape, but rounded edges will help slide into place.
Step 5: Test the Spline
Insert the spline into the groove of the plank already laid in the first room. Do not glue it in yet. Have the first plank for the second room ready to go. With the spline in place, put the first plank up against the spline in the opposite direction to those in the finished room. The groove of this first piece should fit over the spline. Check the concealment of the spline and the transition to make sure there are no gaps. If there are, adjust the spline as necessary to remove any excess space between rooms.
Step 6: Glue the Spline
With the spline tested and ready to go, run a bead of glue along one end of it and insert it into the groove of the last plank in the finished room. You might also add a few finish nails to secure it fully before the glue dries. Make the heads of the nails level so they don’t cause any gaps. With the spline in place you can now begin to lay the planks in the second room.