Rain shower heads are mounted higher than usual overhead showers, designed to create the rain effect.
Sizes and Shapes
Size of the rain shower head dramatically impacts the price. They range from about 6 inches to over 4 feet. Of course, the larger it gets, the more water it is going to consume. For common usage such as for a single person use, 8 to 12 inch shower head should be sufficient.
Most common shapes are round and square. They make no difference functionally with the shape, although the round ones are easier to install.
For aesthetic reasons, rain showers may be mounted flush into the ceiling if false roofing is installed. Other wise a shower arm extending from the ceiling may be used to hold the rain shower head.
Quality and Materials
The best quality ones are made of pure brass that may be chrome coated. The water nozzles are made of high quality silicone designed to withstand years of hard water running through them. Since bathroom water supply is not filtered like drinking water, there is a possibility of dirt blocking these nozzles. Over a period of time, the water flowing through will decrease. You may have to reach up to the shower head and scratch the silicone nozzles slightly to push the dirt out. The ones with brass nozzles are built more rigid and have a higher quality feel, however, they may have to be dismantled for cleaning purposes.
The plumping pipe will have to be routed to the top of shower closet along the ceiling. Avoid the use of sharp L-bends in plumbing pipes. This will drop the water pressure drastically. Try to use pipes with a larger bend radius. If the water pressure is insufficient, you might want to install a self activating pump just outside the bathroom that activates itself while the shower is in use.
It is not recommended to use POP (Plaster of Paris) based false ceiling as it tends to retain moisture and soften up over a period of time. Once the POP ceiling gets moist, mold or mildew might start growing within it that may impact your health. Also, a moist POP ceiling may sag and develop cracks over years of usage.
Use high quality pipe joints with adhesives that join the pipes permanently to avoid any scope for leakage and repairs.