I would like to remove my standard bath tub and install a large shower stall , all on a concrete slab. My question is with the drain. Do I have to slope the new floor over to the existing drain? Break up the concrete and move the drain? How large do pre-made shower bases come?

FXD

You can buy a shower pan that is made specially for this application. It will match your old tub drain. I don't have the pictures but Speedball1 will catch you later and he has pics and installation suggestions. The pans are not cheap>

Kohlor makes a shower base designed to convert a tub to a shower. At $222.00 it's not too bad a price. Check it out at; Kohler Shower Base. Model 72141110 [ Kohler Shower Bases, Shower Pans , showers, shower bases, shower pans, K141110, K-141110 ] - Home & Garden - BizRate - Compare prices & buy - Discount - Price If you wish I can pull up a marble base at over $100.00. You will have to extend the trap raiser to a few inches over the floor line to connect to the drain . Good luck, Tom