The actual installation of a bathtub is a job for two or three men. Even a "light" steel built-in tub weighs over 150 pounds. Others weigh more. Moving a tub around and setting it in place, to say nothing of carrying it up a flight of stairs, is no job for one man. In most other respects, however, installing a bathtub involves little more plumbing prowess than any other job. One man can handle most of the preliminary work and a good portion of the finishing.
Three types of tub are common in the United States. They differ chiefly in the ways they are set in the room. Least pleasing to the eye but common in older homes is the tub set on legs. The second kind, which rests on a base, is a more attractive modification of the first. Most popular of all and certainly the most beautiful is the built-in tub which is installed as an integral part of the bathroom. This discussion will center on the built-in tub. Those problems which belong precisely to the sphere of plumbing however, differ little with the kind of tub installed.
No matter what type of tub you are putting in, you will have to expose the joists near the head of the tub to take care of the waste elbow and the drainage pipe from it to the trap. Hot and cold water service pipes must also run through the opening. If the course of the pipe runs perpendicular to the floor joists, the joists must be notched. Joists with deep notches will have to be reinforced.
Although it is not absolutely necessary to do so, set the built-in tub on the rough or unfinished flooring. If your bathroom is already finished, this may seem like too much work. However, the finish floor can then cover the lower flange of the tub. This facilitates cleaning and aids hygiene in addition to giving your work a professional touch that adds beauty and modernity to your bathroom. The tub and floor join smoothly.
The manufacturer usually provides hangers or supports which bold the built-in bathtub in place. These should be adjustable since, in some cases, the joists shrink or the house settles and a crack develops between the wall and tub. Especially when the built-in tub is also part of a shower installation, the walls must be waterproof and the connection between tub and wall sealed.
The shelves of the conventional hanger angle toward the rear. Two hangers are located at the ends of the tub near the outer edge. The other two are at the far edge of the tub near the ends. Attach each hanger at the proper height for your tub with the single screw that goes through the elongated slot. You are not yet ready to set your tub in place. However, when you have completed the other preparations given below, you will proceed as follows.
Set the tub on the hangers. Level it carefully. Then adjust the hangers so that they actually support the tub and secure them with the remaining screws. If your walls are to be plastered, use the upper shelves; if they are to be filed, use the lower shelves.
You can make a similar installation by using vertical and horizontal wooden supports. Spike the horizontal support to the studs. Then insert the vertical supports beneath it. They provide the additional bracing needed to bold the tub in place. Whenever installing either of the above supports, follow the manufacturer's directions carefully. Keep an accurate level handy and check your work frequently.
Installing the tub
The usual procedure is to install the waste elbow, the overflow pipe, and the mechanical waste before setting the tub in position. If, however, the installation is new and you can reach the area below and adjacent to the bead of the tub easily, you can install them after the tub is in position. In most instances, space limitations or other factors will make this impossible and the parts will have to be assembled before the tub is attached to the supports.
Tilt the tub on its side and wipe the outlet with oil or grease. Next coat the underside of the outlet strainer liberally with putty and slip it into place.
Insert the outlet strainer through the outlet opening in the tub. Working from the underside of the tub, slip the rubber washer over the threaded portion of the outlet strainer and screw the waste elbow in place. Tighten this connection with a bathand-basin plug wrench. Insert the wrench into the outlet and turn it until the outlet and waste elbow squeeze out putty and the rubber washer is fastened securely.
Remove the waste elbow and the overflow tube loose-head couplings from the bath-waste T. Place one set over the waste-elbow tail piece and the other over the overflow tube. Adjust the assembly until the opening of the overflow tube lines up with the overflow opening of the tub. If you have to cut either the arm of the waste elbow or the overflow tube, use a fine-tooth hacksaw.
When the overflow elbow aligns the overflow opening, set it in beveled washer between elbow and the tub. Place portion of the washer at the bottom and slip the overflow plate bolt through the overflow plate and screw it into the threaded section of the overflow pipe.
You can now secure the tub to the tub supports. This requires two men. Make sure the tub is completely leveled and that it cannot slip out of place.
Once you have the tub in place, run a piece of 1 1/2" drain pipe from your trap to within 3" of the bottom of the bath-waste T. Slide the loosehead coupling over the tail piece and allow the tail piece to extend into the drain pipe for about 1". When you have tightened the loose-head coupling, the installation is almost complete.
The mechanical waste consists of a dial and a waste operating mechanism. It is usually linked to a steel supporting frame which in addition to the above contains the hot and cold water valves and the nipple or ell to which the tub spout is connected.
You will have to rely on the manufacturer to supply explicit instructions, but in general the mechanical waste is installed in a manner similar to that outlined for installing the waste arm and overflow. The most important point to remember is that the mechanical operating lever must be set directly in line with the tub outlet if it is to function properly. It is usually advisable to install the waste assembly before the supporting plate is fastened to the studs.
There are several types of concealed valve assembly that can be used to furnish a built-in tub with water. Factory assembled units, consisting of the hot and cold water valves and over-rim spout ejector on a steel support, are highly recommended. They are fairly inexpensive, simple to install, and provide satisfactory service.
Incidentally, an over-rim spout is hygienically a sound choice. Its location prevents all possibility of back siphonage, a condition which permits waste water to enter the water service pipes.
Loosely secure the bracket to the studs at the tub's head. The valves should be 9" to 10" above the rim of the tub; the distance from the valve center and spout ejector to the face of the finished wall should be at least 3" and not more than 3 1/2", and the spout ejector should be centered above the tub outlet.
If you do not plan to install an overhead shower, the only connections that have to be made are those for the hot and cold water-supply piping. Remember that hot water should be delivered to the left valve.
Most valve unions are designed to receive conventional piping; you will have to use adapters for copper tubing, if used.
Perhaps the valve assembly you are working with contains openings situated in the top of the valves and possibly another centrally located in the pipe joining them. These openings are intended for shower piping, and since they are not going to be used they will have to be sealed. Do this by using 1/2" plugs.
Run your supply pipes and join them loosely to the valves. Make certain that the valve assembly is level before tightening the connections. After doing this, screw or nail the supporting bracket to the studs.
Before walling up the area, attach the tub spout and fill the tub to the overflow. Discharge the water and carefully inspect the service and drainage piping. It is much easier to locate and correct deficiencies at this point than after walling up. If everything works, remove spout and faucet trim and wall the area.
The logical time to provide an overhead shower is when the valve assembly for a built-in tub is being installed. A shower can be added with little expense and a minimum of effort at this time.
A highly satisfactory shower that allows you to premix the water to the desired temperature before stepping into it can be controlled by a diverter attached to the valve assembly, or the tub spout. The installation consists of a single riser pipe connected from a fitting situated between the hot and cold water valves. The pipe should be run to a point between 6 1/4 and 6 1/2 feet above the bottom of the tub. Here a 90°' elbow for securing the shower arm is added.
Separate controls, for an overhead shower can be installed. The only advantage this type of arrangement offers is in permitting regulation of the hot and cold water valves without stooping. It does not, of course, require a diverter.