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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. 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. 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. 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. Screw the faucet into the coupling for the water lines through the hole in the surround. Then, screw the strainer cover over the drain opening in the floor of the tub. Add any other accessories you need, such as handles if they are separate from your faucet. Thread the drain chute into the P-trap under the tub. You may need to use PVC pipe to connect the drain chute to the P-trap if they don’t align perfectly. If that’s the case, dry-fit the pieces first and secure the PVC pipe to the chute and P-trap with ABS cement to prevent it from coming loose. Run a bead of silicone caulk along the outside edge of the tub where it meets the floor. Make sure it meets both outside corners to prevent water from getting in between the tub and floor. Smooth out the bead with your finger or a damp rag. To give the caulk and other adhesives time to dry, wait at least a full day. Then, you can turn on the water and check for leaks. If you find any problems, contact a certified plumber.
Set the tub in place and level it. Secure the tub to the studs. Fit a new tub surround. Caulk the tub to the surround and secure the surround to the studs. Connect the water lines and install your accessories. Connect the drain to the P-trap. Caulk the tub to the floor. Wait 24 hours before turning on the water.