Steps:

1. Remove the shower valve handle.

2. Unscrew the cover plates from the shower valve.

3. While standing in the shower, drill ¼-inch holes through the wall behind the shower valve.

4. Cut open the wall behind the shower valve using a drywall saw.

5. Cut a 1×4 to fit behind the type of water pipes in your shower.

6. Screw the 1×4 to the studs on either side of the shower valve.

7. Secure the water pipes to the 1×4 blocking with copper clips.

8. Cover the hole cut in the back wall with a plastic access panel.

9. Apply silicone caulk to the backside of the wall plate, and screw it in place.

10. Place a bead of plumber’s putty around the valve cover and reattach it.

11. Replace shower valve handle and remove excess putty from around the valve cover.