Bathroom and toilet officially speaking is a bathroom unit. A space it takes makes only 6-8% of the general flat area, but considering its importance it is out of competition. It is possible to imagine an apartment without any room or even without a kitchen (there is no kitchen as such in studios, it is joined with the living room), but it is quite impossible to imagine an apartment without a bathroom unit. Major repairs of a bathroom unit is technically quite a difficult task, you can not repair your steam shower yourself easily, it is not a joke. You should leave this work only for highly skilled specialists.
At first, if a quality of mounting and finishing works can be checked by anyone (for example, a wall is curved, a window or a door does not close, or tiles are put roughly), then a quality of plumbing mounting, sewage and electrical systems you cant check. And secondly, as a result of bad work your neighbours can be flooded, constantly clogged sewage system, short circuit failure in the electric wiring due to the contact with water and other serious problems.
We have already written a lot about floors, ceilings and walls, therefore I will remind you briefly that all the materials must be water proof, and there must be damp proofing on the floor. It is also very important to observe the geometry of your bathroom; otherwise it will be difficult to put tiles and to place sanitary equipment in a right way. While connecting towel dryer childish error is the wrong supply of hot water. If sanitary technician says that it is impossible to supply hot water to a towel dryer, trust him and set an electric towel dryer.
Sewage-pipes are mounted with a slope of about 5% and if possible avoid corners of 90. I strongly recommend buying all the pipes and sanitary engineering armature only of the known producers and preferably in the specialized shops. Revisory access holes for the maintenance of plumbing-sewage system must not be too little, otherwise their purpose is lost and in case of some problems it will be necessary to break the walls. All of these are basic moments of plumbing and sewage system mounting, and in general all of this must be the business of your sanitary technicians.
Sanitary engineering equipment. Here we will discuss mixers, water heaters, ceramic bathroom fittings and etc. For showers or soaking tubs, pay attention to the models with a thermostat. There are two regulators in them. One regulates a temperature, and another regulates water pressure.
To my mind, it is exceptionally convenient. Pay attention to toilets flushing systems, which are wall mounted, and wall toilet sinks for them. Electric water heaters. They are divided into running and storage. Running water heaters are smaller, but are more powerful, than storage ones. It can reach 16 kW. Having a lot of other electric devices in an apartment can create heavy load on your electric system.
Whether to have a whirlpool spa wholesale or not, I will not advise anything, because a good bath is a very expensive thing and its up to you to decide, whether to pay 1000-3000 for it. I will only tell you, that connection of a spa does not differ from ordinary bath connection.
I hope that these information will help you during repair works, when buying materials and dealing with builders.