How to Center a Shelf When the Wall Studs Won't Cooperate

This is the spot I want to hang my shelf. The toilet is under that white board. I wanted it centered over the toilet

Using my handy dandy stud finder, I located the stud that will fall behind my shelf. To be sure I hit wood, I drilled a hole with a tiny bit. It worked!!!

I found an old board that was in my basement. It was the right height and I cut it down to the width of my shelf. I gave it a few good coats of white paint.

You can see my dilemma with the location of the hanging holes on the shelf. I measured their exact location, transferred that info to the white board, and then set the hanging screws in place. I left them protruding about 1/8" from the board. I set the shelf onto the screws to test their placement. Thankfully it was good.

This next step is the secret to a stabilized shelf. I set the board on the chair railing, exactly centered over the toilet. I then measured from the corner to the hole I had drilled into the stud. I made a mark on the board about 1/2" from the top edge. I then put a second mark on the bottom edge, the same distance from the corner.

Next, I made marks on the opposite end of the board the same distance from the edge. I drilled pilot holes and inserted 2" screws just enough so they wouldn't fall out.

I wanted the top of the shelf about 15" above the chair railing so I made a mark for reference. I then held up the board at that height, centered over the toilet, and drove the upper right screw in but not all the way.

Then, I used a level to position the board and drove the bottom right screw in place. These two screws are what's holding the shelf safely in place because they are driven directly into the stud.

The last two screws went into the drywall and are of no consequence other than a balanced appearance.

I touched up all of the screws with white paint. (not shown)

Lastly, I hung the shelf on the two screws that were already in the board. Now I just need some prettier towels to finish it off!