How Securing the Tub and Surround?
Set the tub in place and level it. Carefully position the tub in the alcove so that the drain rests over the drain opening in the floor. Place a level on each side of the tub. If any spots are uneven, position hardwood shims underneath the tub and glue them in place. Some manufacturers may advise you to spread mortar on the floor and set your tub on the mortar to secure it in place.
Secure the tub to the studs. There will be a small flange, or vertical lip, around the outside of the tub. Follow the manufacturer’s directions to secure the flange to the studs in the wall. In most cases, you can use a hammer to drive roofing nails through the flange to secure it to each stud in the wall.
Fit a new tub surround. The surround is made up of the panels that protect the wall around your tub from moisture and mildew. First, dry-fit the surround and mark the location of the accessories, including the faucet and water handles. Ensure that the faucet will line up with the water lines in the wall. Then, cut out the accessory openings with a jigsaw.
Make sure you measure the location for accessories multiple times before cutting into the surround!A one-piece surround is the easiest type to install. Caulk the tub to the surround and secure the surround to the studs. Place a bead of silicone caulk around the entire perimeter of the tub on the ledge next to the flange. Then, carefully set the surround on top of the silicone caulk.
Next, use a drill to screw the surround into each wall stud. Aim to use a screw every 6 inches (15 cm) up the length of the surround. Be sure to choose silicone caulk meant for use in bathrooms.