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Bathroom Systems

A grasp of basic plumbing, electrical, and heating and cooling principles will help you plan your bathroom better.

Bathroom Plumbing

Two main components make up any plumbing system - the water supply and the drain, waste, and vent system. Building codes often require a 1-inch diameter supply line from the street to the house for new construction. For multiple bathrooms, a 1-imch line must run all the way to the water heater. If you own an older home, there's a good chance your main supply line is smaller, so you may not have optimal water pressure if you increase the number and size of fixtures. If you have several bathrooms or want a luxury fixture, you may have to put in a new supply line.

Extending water supply lines is usually straightforward but expensive. Creating a new drain and vent stack is also a big job. To keep your bathroom remodeling project simple, try to place fixtures within a few feet of your home's main vent stack. Your local building code will specify the maximum distance that fixtures may be placed from the vent lines.

Bathroom Electrical Wiring

The modern bathroom uses a good deal of power. If you have an older house with a small-capacity electrical service (less than 100 amps), you may need an upgrade to acommodate the latest amenities. Consult an electrician, especially if you plan to install a power-hungry whirpool, steam generator or sauna.

If your electrical system has not been upgraded for 20 years or more, you probably need to install ground-fault circuit interrupters. Required by code in bathrooms, they prevent accidental shock or electrocution.

Bathroom Heating

If you want to link your bathroom to your forced-air central heating system, you'll need to extend the supply and return the air ducts that connect your furnace - a costly job that requires professional know-how. Auxiliary heating is less expensive to install and works well in a small space such as bathroom. A wall- or ceiling-mounted heater will provide plenty of heat (a gas heater must be vented to the outside). Radiant floor heating is another option.

You can use the radiant floor heat to warm the entire room, or just to chase the chill from the tile. For true space heating, especially in cold climates, a system that carries hot water through a series of tubes underneath the floor is most effective and energy efficient. If the goal is merely to warm the floor in a room that already has heat, a thin electric warming mat can be laid between the subfloor and the tiles. Mat systems are cheaper to install, but more expensive to operate.

In addition to delivering heat, it is critical to retain it. Make sure that insulation gets into all the spaces, like behind the shower or tub. Ridged foam can be cut to fit tight into the stud bays. Spray-in foams are even more effective and will fill the gaps - and with these you don't need a vapor barrier.

Bathroom Ventilation

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Most local building codes require that the bathroom be ventilated, and for good reason - poor ventilation allows humid air to condense in the walls, where it can cause extensive structural rot in a short amount of time. For good ventilation you need an exhaust fan that's powerful enough to completely replace the air in the room at least eight times an hour.

Every fan has a CFM rating, which tells you how many cubic feet of air you can move in a minute. To determine what CFM rating your fan should have, multiply the total cubic footage of the room by 8 and then divide by 60. The smallest fans on the market move about 60 cubic feet of air per minute, enough to clear moisture from a 5-by-8 foot bathroom. For bathrooms larger than 100 square feet, one needs a ventilation rate based on the number and type of fixtures present. Toilets, showers and tubs require 50 CFM each; a whirpool tub requires 100.

Your fan should be controlled by a timer switch or, even better, a humid-instant switch that operates the fan when the humidity levels in the room require it. This will keep the fan on even after you've left the bath without you having to remember to turn it off.