Removing a cast iron bathtub for a bathroom remodel job, is a tough job, not in the sense of tough on skills, but tough as in tough backbreaking work. Cast iron bathtubs weigh about 300 lbs. and are in a tight location making even moving it out of place difficult.
The first thing you need to do is disconnect the plumbing to the old tub. You will need to shut off the water to the tub, in many homes the water supply to the whole house will need to be shut off. Others may have shut off valves in the basement or in an access panel in the wall behind the tub, if you do not have an access panel I would recommend cutting one on the wall on the backside of the drain and mixer valve, this will be needed later anyway. In a house where the whole house has to be shut off if the pipes are copper, CPVC or, PEX you can cut the pipes then place SharkBite end caps on the pipe to seal them so you can turn the water back on to the rest of the house. You can then remove the old mixer valve and spout giving you additional room.
The waste and overflow tub drain will also have to be disconnected before the tub can move. To disconnect the waste and overflow remove the screws holding the overflow plate and lever in place then remove the plate and lever lifting the stopper mechanism out with it. On tubs with pop up stoppers you will have to lift the pop up stopper out of the drain before the stopper mechanism can be removed. After removing the overflow plate the next task is to remove the drain flange. On tubs that have cross bars in the drain flange a “Dumbbell Wrench” can be used to remove the flange by unscrewing it counter-clockwise. Sometimes the flange can be tough to remove and cutting through the flange with a hacksaw and chiseling the flange in a circular motion can remove it. You can also just reach in from the access panel and cut the drainpipe or dismantle it. Make sure that once the drain is disconnected, you stuff rags into the opening to prevent debris from going down the drain, and this will prevent problems later.
If you have a free standing or, claw foot tub once the supply lines and the drains have been disconnected you are ready to get a helper and carry the tub out. I have used the turtle method as well as just grabbing the ends and going. Make sure that your entire path out has the clearances you need before starting the carry.
The bathtub has a flange around 3 sides of the tub with the wall coming down inside the tub flange. The walls will have to be removed above the tub flange to allow its removal. Once the walls have been removed and the tub is in the clear to be removed the fun begins. There are two schools of thought on how to remove a tub at this point none of them easy. One is to lift the tub out in one piece and carry it out while the other is to break the tub in pieces and carry the tub out.
To lift the tub you will need a helper to help lift and move the tub, pry bars, crowbars and other tools to get the tub moving out of place. A “Wonder Bar” or, “Super Bar” with it’s flat profile is a great tool for prying loose a cast iron bathtub. Keep in mind the size of the tub and obstacles in the bathroom that will have to be cleared to get the tub in and out of its space. The tub fits tight to the studs and cannot move in a diagonal manner until it is clear from its alcove. Doors, molding, radiators, baseboards, toilets, and sinks often have to be removed to allow the tub to be removed and it is far easier to remove these before a tub that has been partially removed crowds them. Consider the entire path in and out of the house as well. ¼ of the way down the stairs is not when you want to discover that a handrail on the wall needs to be removed. These same fixtures will probably be in the way of installing the new tub as well, so plan ahead. When prying keep in mind damaging the tile by prying can occur. While the wall probably is being completely replaced because of the section being removed for clearance, if you are planning on keeping the floor use wood blocks when prying against the flooring to prevent damage. From here on it is pure “Bull Work” to tear out the tub and carry it outside. One thing I have done is get inside the upside down tub and play turtle to carry it out with a helper to guide and assist me.
The other option is to smash the tub with a sledgehammer then carry out the pieces. There is nothing easy about this either and you still will need a clear path to get the new tub in place. However, with the smash method it may be a one-man job to remove the old tub. When you remove a cast iron tub using the smash method there is a hazard where shards of the porcelain tub finish will fly off when you hit it with the sledgehammer. Take an old blanket that you don’t care about and wet it then place it over the tub, this will help containing the flying debris. The sound of the hammer hitting the tub will be quite loud as well. Make sure you use proper personal protective equipment to prevent injury from the flying porcelain shards and noise. Long pants, long sleeve shirt, gloves, ear protection, eye and face protection are needed. When I said sledgehammer I meant “Think Big” I would consider 10-12 lb. sledges to be minimum. Start the breaking about ½ to 2/3 of the way down the tub from the drain and start swinging trying to break the tub into 2 large pieces. Of course you will have a large number of smaller pieces that break off but the 2 larger pieces will be manageable to carry out.
Whatever method you choose you will probably wonder if the other was easier.