For best laundry room ventilation to remove excess humidity, a powered ceiling or wall exahust fan is required.
What Happens When Your Laundry Room Isn't Ventilated Properly? Off-gassing from different soaps and detergents combined with humidity from home appliances leads to poor indoor air quality. If your laundry room is not properly ventilated you can expect excess humidity and lint fire hazards to pose a threat to your home.
M1502.
The maximum developed length of a clothes dryer exhaust duct shall not exceed 35 feet from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet for each 45-degree (0.8 rad) bend, and 5 feet for each 90-degree (1.6 rad) bend.
If your home has a utility room with a washing machine or tumble dryer, you should also have some form of ventilation there too.
Not less than 0.5 cfm per square foot (0.0025 m3/s × m2) of machinery room area or 20 cfm (0.009 m3/s) per person. A volume required to limit the room temperature rise to 18°F (10°C) taking into account the ambient heating effect of all machinery in the room.
The room's square footage will tell you what the CFM should be (12 x 12 = 144).
(In a 4" (102 mm) diameter pipe, this requires at least 105 CFM of air flow.) Single dryer venting systems are defined as systems that have only one dryer unit attached to a residential-type 4" (102 mm) diameter rigid metal vent system.
In particular, your laundry room should have a drain. Well-made homes have laundry drains on the floor in case you have excess water from a broken pipe or a malfunctioning machine. These drains along with a few extra exposed hoses give you the opportunity to be creative with the plumbing in this room.
Drying your clothes produces hot, humid air in your dryer. A dryer wall vent allows this air to escape through a system of ducts or pipes connected to the back of the dryer. Also called clothes dryer venting, this type of dryer duct installation removes moisture and lint so your clothes can dry.
Unvented pipes are at a high risk of overflowing and releasing harmful gases. For laundry standpipes, the vent should be at least 1 ½” in diameter and located within 5 feet of the trap.
The easiest and most effective way to vent a washing machine is to run the drainpipe into your home's vent stack. The vent stack, or waste stack, is a vertical pipe that connects to your home's plumbing and exits through the roof.
A laundry room sink helps you easily rinse attachments and wipe down surfaces, which will make a world of a difference in improving the longevity of your washing machine and the overall cleanliness of your laundry room. Prevent excess mess in your washing machine and in your kitchen.
However, on average, most residential clothes dryers have an exhaust CFM of around 150-200.
According to the International Building Code, a dryer vent pipe must be fabricated of smooth metal and at least 4-inches in diameter. It must extend all the way to a termination point outdoors. Total length of the vent pipe cannot exceed 35 feet.
Install One or More Exhaust Fans
Much like bathrooms, laundry rooms can be effectively ventilated with either windows or exhaust fans. However, as with windows, exhaust fans must be used correctly to supply the intended benefits. These fans should be kept running throughout the duration of all wash and dry cycles.
The laundry room can sometimes be a forgotten area of the home when it comes to Indoor Air Quality (IAQ). Most of the IAQ focus when it comes to ventilation is on the kitchen and bathrooms and rightfully so. However, the laundry room can be a large source of contaminants in your home.
The air now has to re-pressurize to regain its turbulent flow so it can continue to push its way down the duct. It requires about 24′ or two feet to do this. This is the 'Two-Foot Rule?. Ideally, you should allow at least 24′ between takeoffs and at the end of any duct run.
Sizes range from 4 to 16 inches in diameter, with 6 to 10 inches being the most common for main supply and return ducts. Their round shape allows for smoother airflow with less resistance, which can enhance your HVAC's efficiency.
Based on nearly 40 years of dealing with laundry rooms, I feel the minimum size for one of these rooms should be 9 feet wide by 11 feet long. Bigger is better. The door leading into the room should be at least 32 inches wide.
Plumbing codes generally don't require a floor drain in the laundry room of a single family residence, but it comes in handy in case of overflows. If you choose to install one, the drain pipe must have a minimum diameter of two inches. The drain opening, which must have a removable strainer, can't be under a fixture.
Closets, bathrooms, laundry rooms and outdoor rooms like garden sheds and pool houses can also be enhanced to serve as safe rooms.