Do they make a double sided tongue?

Q: I’m installing some hardwood flooring. I am going around a corner and transitioning the strips together (L pattern), but I’m ending up with groove to groove at the corner. Do they make a double sided tongue, or can I just nail the groove ends down?

A: You local flooring retailer may sell splines to use for this purpose. I used some today. the ones I have a made by the makers of Mirage floors. I generally pre drill the bottom of one row on the groove side and nail. Then apply some adhesive to one edge of the spline. Insert into groove of boards I nailed. Spread adhesive (I use moisture cure urethane adhesive.) Where next row will sit. Also apply a bit of adhesive to the top part of the groove on the boards for the next row. Tap the 2 rows together and nail the facing row in the top of the tongue. It takes more time, but is far better than face nailing 2 rows.

Similar Q: I have two grooves together instead of one tongue, one groove. Do they make filler strips for this or can I make my own?

A: Yes, split tongues or splines come pre made. Mirage makes some good ones, but others can be found. I usually buy them by the bundle, because it isn’t worth my time to make my own. If you only need a handful one time, you could make your own.