The Bathroom Vent System

Bathroom ventilation systems are designed to exhaust odors and damp air to the home’s exterior. A typical system consists of a ceiling fan unit connected to a duct that terminates at the roof.  Ventilation systems should be installed in all bathrooms, including those with windows, since windows will not be opened during the winter in cold climates.

Fan Function  

The fan may be controlled in one of several ways.

  • Most are controlled by a conventional wall switch. 
  • A timer switch may be mounted on the wall.
  • A wall-mounted humidistat can be pre-set to turn the fan on and off based on different levels of relative humidity.

It’s not always easy to tell whether the bathroom vent fan is operating as it should.  Newer fans may be very quiet but work just fine. Older fans may be very noisy or very quiet. If an older fan is quiet, it may not be working well. 

Bathroom ventilation fans should be periodically checked for dust buildup, which can impede air flow. Particles of moisture-laden animal dander and lint are also attracted to the fan because of its static charge. Homeowners should regularly clean dirty fan covers to prevent this kind of buildup.

Defects

 The following conditions indicate insufficient ventilation in the bathroom:

  • stains on the bathroom walls and/or ceiling; 
  • corrosion of metal parts of the vent system;
  • visible mold on the walls and/or ceiling;
  • peeling paint or wallpaper;
  • frost on the interior of the bathroom window; 
  • high indoor humidity; and/or
  • improper duct termination.

Duct Termination

The most common defect related to the bathroom’s ventilation system is improper termination of the duct. Vents must terminate at the home’s exterior. 

The most common improper terminations locations are:

  • mid-level in the attic. These are easy to spot;
  • beneath the insulation in the attic.  The duct may terminate beneath the insulation or there may be no duct installed; and 
  • under attic vents. The duct must terminate at the home’s exterior.

Improperly terminated ventilation systems may appear to work fine from inside the bathroom, so the homeowner or inspector may have to look in the attic or on the roof. Sometimes, poorly installed ducts will loosen or become disconnected at joints or connections.

Ducts that leak or terminate in the attic can cause problems from condensation. Warm, moisture-laden air will condense on cold attic framing, insulation and other materials. This condition has the potential to cause health and/or decay problems from mold, or damage to building materials, such as drywall. Moisture buildup also reduces the effectiveness of thermal insulation. 

Mold growth is another undesirable consequence of improperly vented damp air.  Even though mold growth may take place primarily in the attic and basement/crawlspace, mold spores can be sucked into the living area of a home by low air pressure, which is usually created by the expulsion of household air from exhaust fans in bathrooms and kitchens, and from clothes dryers and heating equipment. 

Improper Ventilation 

Ventilation ducts must be made from appropriate materials and oriented effectively in order to ensure that damp air is properly exhausted.

Ventilation ducts must:

  1. terminate outdoors. Ducts should never terminate within the building envelope; 
  2. contain a screen or louvered (angled) slats at its termination to prevent bird, rodent and insect entry;
  3. be as short and straight as possible and avoid turns. Longer ducts allow more time for vapor to condense and also force the exhaust fan to work harder; 
  4. be insulated, especially in cooler climates. Cold ducts encourage condensation; 
  5. protrude at least several inches from the roof; 
  6. be equipped with a roof termination cap that protects the duct from the elements; and 
  7. be installed according to the manufacturer’s recommendations.

The following tips are also helpful. Ventilation ducts should:

  • be made from inflexible metal, PVC, or other rigid material. Unlike dryer exhaust vents, they should not droop; and 
  • have smooth interiors. Ridges will encourage vapor to condense, allowing water to back-flow into the exhaust fan or leak through joints onto vulnerable surfaces.

Above all else, a bathroom ventilation fan should be connected to a duct capable of venting water vapor and odors to the outdoors. Mold growth within the bathroom or attic is a clear indication of improper ventilation that must be corrected in order to avoid structural decay and respiratory health issues for family members.

Under-Sink Plumbing

Sinks are a category of plumbing fixtures that includes kitchen sinks, service sinks, bar sinks, mop sinks and wash sinks. A sink is considered a different item than a lavatory (or a bathroom sink), although the terms are often used interchangeably. Sinks can be made of enameled cast-iron, vitreous china, stainless steel, porcelain-enameled formed steel, non-vitreous ceramic, and plastic materials.

Sink waste outlets should have a minimum diameter of 1-1/2 inches. Most kitchen sinks have an opening of 3-1/2 inches in diameter. A food-waste grinder has a standard opening of 3-1/2 inches, and so do most kitchen sink basket strainers. A strainer or crossbar should be provided to restrict the clear opening of the waste outlet.

Plumbing Requirements for Garbage Disposals

Food-waste grinders (also known as garbage disposals and disposers) are designed to grind foods, including bones, into small-sized bits that can flow through the drain line. Using them to dispose of fibrous and stringy foods, such as corn husks, celery, banana skins and onions, is not recommended because fibers tend to pass by the grinder teeth, move into the drain pipe, and cause drains to clog.

Water must be supplied to the grinder to assist during its operation in transporting waste. The water flushes the grinder chamber and carries the waste down the drainpipe. Blockage may result if the grinder is used without running the water during operation. Grinders should be connected to a drain of not less than 1-1/2 inches in diameter. Food-waste grinders are supplied with water from the sink faucet. They do not add to the load used to compute drainage pipe sizing. The drain size required for a grinder is consistent with that for a kitchen sink.

Plumbing Requirements for Dishwashers

The water supply to a residential dishwasher should be protected against backflow by an air gap or backflow preventer. The machine must be equipped with an integral backflow mechanism, or the potable water supply must have either a backflow preventer or an air gap. The discharge pipe from the dishwasher should be increased to a minimum of 3/4-inch in diameter. It should be connected with a wye fitting to the sink tailpiece. Before connecting to the sink tailpiece, the dishwasher waste line should rise and be securely fastened to the underside of the counter. The combined discharge from a sink, dishwasher, and waste grinder is allowed to discharge through a single 1-1/2-inch trap.

Maintenance Tips

Homeowners should take care not to overload the garbage disposal or the dishwasher, as this can lead to leaks and backups in the sink and the plumbing system. A backup at the kitchen sink may mean that the garbage disposal is clogged, or the plumbing line has some obstruction that prevents proper drainage. It’s important that homeowners understand the cause of the problem, as well as the proper way to repair it, before dismantling pipes under the sink. The right size of fittings and replacement parts, as well as proper drainage (including slope and traps) will ensure that the sink will work as it should following a repair, which is why most maintenance issues are best left to professionals, unless the homeowner has the proper instruction, parts and tools available.

Bathroom Sinks (Lavatories)

A lavatory is a washbasin or sink located in a bathroom or washroom. “Lavatory” means washbasin or sink, and is derived from the Latin word lavatorium, which means washing vessel, and the French word laver, meaning “to wash.” Lavatories come in a variety of shapes and sizes. They are available in enameled cast-iron, vitreous china, stainless steel, porcelain-enameled formed steel, plastic, and non-vitreous ceramic. They can be wall-mounted, hanger-mounted, under-mounted, pedestal, rimmed, and above-center basin types.
Countertops integrated with lavatories are constructed of a variety of materials, including ABS, PVC, gel-coated fiberglass-reinforced plastic, acrylic, polyester, and cultured marble. Plastic vanity tops should be impregnated with fire-resistant chemicals to reduce the fuel contribution of the lavatory during a house fire or the accidental fire from a plumber’s torch. They are also made to resist the effect of a burning cigarette left unattended on the vanity top.

Lavatories should have a waste outlet of at least 1-1/4 inches in diameter. Each lavatory must have a strainer, a pop-up stopper, a crossbar, or other mechanism to prevent items such as rings, toothbrushes and cosmetic items from dropping into the drain.

Lavatory Overflows

Former standards required lavatories to have an overflow, but that is no longer the case. The overflow is now an option of the manufacturer. The reason for not requiring an overflow at a lavatory is because of the lack of use of the overflow, which can cause bacterial and micro-organism growth.

Where a lavatory does have an overflow installed, the cross-sectional area of the overflow should be a minimum of 1-1/8 inches; anything larger can promote bacterial and micro-organism growth. The overflow should be able to prevent overflowing of the sink for a minimum of five minutes when tested from the onset of water flowing into the overflow’s opening.

Maintenance Tips

There are many different designs of lavatories, including artisanal styles that sit up on the vanity, rather than being dropped into a recessed cavity in the vanity or countertop. Regardless of the style or whether it includes an overflow opening, the washbasin should be securely attached to the vanity, be free of cracks and other defects, and have gaps that are properly caulked to prevent moisture buildup, which can lead to unsanitary conditions, including mold growth.

Showers & Bathtubs

Bathtubs

Bathtubs are made from many different types of materials, including enameled cast-iron, porcelain-enameled steel, and plastic. Plastic tubs are made from materials including ABS, PVC, fiberglass, fiberglass-reinforced plastic, acrylic, and cultured-marble acrylic. Bathtubs that are equipped with shower fixtures should be manufactured with slip-resistant surfaces. Bathtubs should have a drainage outlet (tailpiece) with a minimum diameter of 1-1/2 inches. Every tub should be equipped with a stopper. The bathtub should have an overflow outlet installed. The overflow prevents flooding if the tub is being filled while unattended, and prevents overflow of the water when a person enters a tub that is full.

Fire-Resistance

Bathtubs made of plastic are tested for fire ignition. They are made with fire-resistant chemicals to reduce their fuel contribution in a house fire, or an accidental exposure to a plumber’s torch.

Large Bathtub Loads

Some bathtubs are so large that they can accommodate more than one person at a time. These larger bathtubs may need special and additional structural support underneath them to adequately support the load.
A 3×4-foot bathtub may have a capacity to hold 200 gallons or more. The weight of the bathtub, water, and occupants may total over 1 ton, considering:

200 pounds for the bathtub
1,600 pounds of water
350 pounds for two people
= 2,150 pounds

A very large tub may cause structural problems because live-loading for a typical residential home is 40 pounds per square foot. The live load for a 3×4-foot occupied tub may be assumed to be only 480 pounds, but may weigh over 2,000 pounds while it is in use.

Maintenance Tips

The homeowner should make sure that the tub is free of cracks, rust and other staining, and that all edges, gaps and surrounding tile are adequately caulked to ensure that moisture cannot leach behind the tile work and drywall, which can lead to leaks and structural damage behind walls that won’t be evident until the issue becomes extensive and expensive to fix.

Showers

Plastic, pre-fabricated shower units are constructed of various synthetic materials, including ABS, PVC, gel-coated fiberglass-reinforced plastic, cultured marble, cast-filled fiberglass, polyester, cultured marble acrylic, and acrylic. These shower units are impregnated with fire-retardant chemicals to reduce the fuel contribution during a fire, and protection against an accidental burn by a plumber’s torch.

The showerhead height is not typically regulated by building codes, but the head is commonly installed 70 to 80 inches above the shower floor.

Shower Water Pipes

Water-supply pipes from the shower valve to the showerhead outlet — referred to as the shower riser pipes — whether exposed or not, must be firmly attached to a structural component to prevent the pipes from leaking caused by stress fractures or joint failures. Movement of the showerhead may move the riser piping, possibly causing failure of the piping. The risers must be firmly secured.

The common practice for installing the riser pipe is to place a drop-ear elbow at the top of the riser pipe. The elbow has two wing connections. They can be screwed to a structural backing board, such as a 2×4. A pipe strap can be used instead of a drop-ear elbow. When the riser is exposed, the manufacturer will typically provide a strap or attachment device to match the finish of the fixture and pipe. The strap or attachment device should be firmly secured to a structural component.

Shower Outlets

The waste outlet for a shower should have minimum diameter of 1-1/2 inches. The shower outlet should have a strainer that is at least 3 inches in diameter, with dimensional openings in the strainer of at least a 1/4-inch. The strainer should be removable.

Shower Area

A shower compartment should have an interior cross-sectional area of at least 900 square inches. This will allow an average-sized adult to clean the lower body while bending over. A shower that’s any smaller would be inadequately sized. Shower compartments should be at least 30 inches in minimum dimension. This measurement is based on the movement of an adult body inside a shower and measured from the finished interior dimension of the compartment, excluding fixture valves, showerheads, soap dishes and grab bars. There are exceptions for showers having fold-down seats, and those with compartments at least 25 inches wide and 1,300 square inches in cross-sectional area.

The exception allows for a shower with one dimension being 25 inches, provided the compartment has at least 1,300 square inches of cross-sectional area. This is useful to contractors and DIY homeowners who remove an old bathtub and install a standup shower fixture in the same space.

Shower Walls

Showers and bathtubs with installed showerheads should be finished with a non-absorbent surface that shall extend to a height of not less than 6 feet above the floor level of the room, or 70 inches above the shower floor. It should be constructed of smooth, corrosion-resistant and non-absorbent materials to protect the structural components from moisture damage. The gypsum or cement wallboard behind ceramic tiles of a shower wall should be water-resistant. The water-resistant material is not required in the rest of the bathroom, although it is a common practice to use water-resistant gypsum wallboard in other areas of the bathroom because of the moisture levels.

Shower Access and Egress Opening

Many injuries in a home are related to accidents in the bathtub or shower. The minimum opening requirements for access and egress allows an adult enough room to safely step into and exit the shower area without having to twist or turn through a narrow opening. The shower opening (or access and egress opening) should be at least 22 inches of clear and unobstructed finish-width. The 22-inch width is based on the approximate shoulder width of an average-sized adult, and provides comfortable access to service the valves, showerheads and drain. It allows for emergency response and rescue access, and emergency egress.

Shower Floors

The shower floor surface must be watertight with smooth, corrosion-resistant, non-absorbent, waterproof materials. Joints between the floor and walls of the shower must be sealed or flashed to prevent water penetration. Ideally, there should be some type of slip-resistant floor surface. The shower floor structure needs proper support by a smooth and structurally sound base. The base of the shower floor should be designed to support both dead (structural) and live (people and water) loads.

Shower pans and liners are installed under and around showers to prevent moisture intrusion from getting into the structural supports under and behind the shower enclosure. They must meet specific standards for material, installation and size in order to support both dead and live loads.

Shower Glazing

Glass doors enclosing the shower should be made of safety glazing. If a window is installed in the shower, the window should be made of safety glazing to provide protection. If a person slips or falls inside the shower, s/he may be seriously injured by broken glass if the glass is not made of safety glazing. The safety glazing should be correctly labeled by being permanently marked in a corner, legible and visible after installation, and indoor applications should be marked “indoor use only.”

Maintenance Tips

Similar to other bathroom fixtures, the homeowner should make sure that the shower is free of cracks, rust and other staining, and that all edges, gaps and surrounding tile are adequately caulked to ensure that moisture cannot leach behind the tile work and drywall, which can lead to leaks and structural damage behind walls that won’t be evident until the issue becomes extensive and expensive to fix. Additionally, if the glazing for the showers doors is damaged, it should be replaced, as cracked glazing can break without notice and cause serious injuries.

Toilets & Bidets

A water closet in the U.S. is commonly referred to as a toilet. The term “water closet” originates from the time when plumbing was brought indoors, and defecation took place in a small, closet-size room with a pot.

Toilet Styles

There are three styles of water closets: close-coupled, one-piece, and flushometer valve. The most common is the close-coupled water closet, which has a bowl and separate gravity-type tank or flushometer tank that is supported by the bowl. A one-piece water closet is constructed with the gravity-type tank or flushometer tank and bowl as one integral unit. A flushometer-valve water closet is a bowl with a flushometer valve. Water closet bowls come in six styles: blow-out, siphon jet, reverse trap, wash-down, siphon vortex, and siphon wash.
Toilet Measurements
A water closet has a water consumption limit of a maximum average of 1.6 gallons of water per flush. The general bowl rim height above the floor is between 14 and 15 inches. Other rim heights may be needed for water closets used by children (10 inches), and the elderly and persons with physical disabilities (18 inches). Elongated water closet bowls are required for public or employee use but are often installed in homes. An elongated bowl is 2 inches longer than a regular bowl.

Defects at Toilets

The water closet (toilet) may have a clogged drain. While flushing the toilet, watch the flush performance, and use toilet paper as part of this test. There should be no excessive odors around the water closet. Check the flooring around the toilet with your foot. Using the side of your leg, check to see if the toilet is securely attached to the floor. If it wobbles, the screws at the base may be loose, or the wax ring that adheres the fixture to the waste pipe may be worn or of the wrong size. If so, it should be replaced. Look for dampness around the bottom of the toilet base. Toilets sometimes run continuously. Check for a water shut-off valve. Some toilets are mistakenly connected to the hot water system. Tank lids are often cracked. Any defective parts should be immediately replaced to avoid backup flooding.

Bidets

Common in much of Europe and Asia, bidets are toilet-like plumbing fixtures designed to promote posterior hygiene. They’re becoming increasingly common in North America. Contrary to popular belief, a bidet is not an alternative to a toilet. Its purpose is as a hygiene device following toilet use. However, some bidets have been incorporated into toilets, especially in bathrooms that are not large enough for both fixtures.

Bidets, like toilets, are typically made from porcelain and contain a deep recess within a wide rim. They emit an arc of clean water from a nozzle that may be located beneath the rear of the rim or deep within the fixture’s cavity. Users can sit on the rim (or seat, if it has one), or straddle the fixture and face in either direction. He or she can decide which direction to face based on the water jet configuration and the part of their body that needs cleaning. Water temperature and pressure can be adjusted with knobs in order to arrive at the desired settings.

Some bidets come with built-in air dryers. Toilet paper can be used for this purpose if no dryer is available. The bidet can be rinsed after use to keep it clean.

Benefits

People who suffer from hemorrhoids, irritable bowel syndrome, or have recently had surgery can find relief with the more gentle water flow of a bidet.
As the bidet requires less operator mobility, they are easier to use for the elderly, disabled and obese.
Many believe that the use of bidets is more hygienic and effective than toilet paper.
Safety Precautions

Users should familiarize themselves with the rate of temperature and pressure changes that occur when they adjust the controls. Sensitive regions can be burned if the user is not careful, and high water pressure can be irritating.
Users should know in advance the direction of the water arc and position themselves accordingly. The spray can be powerful enough to strike a person in the face.
Bathroom Sinks (Lavatories)

Lavatories

A lavatory is a washbasin or sink located in a bathroom or washroom. “Lavatory” means washbasin or sink, and is derived from the Latin word lavatorium, which means washing vessel, and the French word laver, meaning “to wash.” Lavatories come in a variety of shapes and sizes. They are available in enameled cast-iron, vitreous china, stainless steel, porcelain-enameled formed steel, plastic, and non-vitreous ceramic. They can be wall-mounted, hanger-mounted, under-mounted, pedestal, rimmed, and above-center basin types.
Countertops integrated with lavatories are constructed of a variety of materials, including ABS, PVC, gel-coated fiberglass-reinforced plastic, acrylic, polyester, and cultured marble. Plastic vanity tops should be impregnated with fire-resistant chemicals to reduce the fuel contribution of the lavatory during a house fire or the accidental fire from a plumber’s torch. They are also made to resist the effect of a burning cigarette left unattended on the vanity top.

Lavatories should have a waste outlet of at least 1-1/4 inches in diameter. Each lavatory must have a strainer, a pop-up stopper, a crossbar, or other mechanism to prevent items such as rings, toothbrushes and cosmetic items from dropping into the drain.

Lavatory Overflows
Former standards required lavatories to have an overflow, but that is no longer the case. The overflow is now an option of the manufacturer. The reason for not requiring an overflow at a lavatory is because of the lack of use of the overflow, which can cause bacterial and micro-organism growth.

Where a lavatory does have an overflow installed, the cross-sectional area of the overflow should be a minimum of 1-1/8 inches; anything larger can promote bacterial and micro-organism growth. The overflow should be able to prevent overflowing of the sink for a minimum of five minutes when tested from the onset of water flowing into the overflow’s opening.

Maintenance Tips

There are many different designs of lavatories, including artisanal styles that sit up on the vanity, rather than being dropped into a recessed cavity in the vanity or countertop. Regardless of the style or whether it includes an overflow opening, the washbasin should be securely attached to the vanity, be free of cracks and other defects, and have gaps that are properly caulked to prevent moisture buildup, which can lead to unsanitary conditions, including mold growth.