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While a steaming hot bath or shower might be good for the soul, hot, humid air in an enclosed room like a bathroom could cause some damage. Unsightly mold and mildew could grow on bathroom surfaces as a result of insufficient ventilation. This can be remedied with the appropriate extraction fan and ducting.
PVC pipe can be used for bathroom fan venting provided the specific type of PVC pipe used has a flame spread index of less than 200. PVC Schedule 40 foam core pipe is the perfect material for venting ducts as it is designed for drain, waste, and vent purposes.
A correctly installed and vented bathroom fan ensures moist air and unwanted odors are dealt with before they become a problem, especially in rooms with little to no ventilation. This article discusses the requirements and types of PVC piping when installing a bathroom fan.
PVC Pipe Ducting Appropriate for Bathroom Fan
According to Chapter 16 of the International Residential Code, the materials for all HVAC duct systems must conform to industry standards.
M1601.1.1.1 specifically mentions different materials, but no mention is made of using PVC plastic or not in the code.
This section states that all materials used for above-ground duct systems should have a flame spread index not greater than 200. PVC has a low flame spread, so it is appropriate for use as ducting for a bathroom fan.
While IRC codes are used as the industry standards, local codes and regulations take preference.
Our informative article, What Kind Of Duct To Use For Bathroom Fan, explains the different types of bathroom fan ducts.
Requirements of PVC Pipe for Venting Bathroom Fan
When using PVC piping to vent your bathroom fan, check the regulations in your area for the type of pipe that can safely be used. Some considerations when using PVC pipe are:
- The PVC pipe should be for drain, waste, and vent purposes only and suitable for gravity-fed waste elimination systems.
- The PVC should be designed for non-pressure systems with temperatures not exceeding 140 °F (60 °C).
PVC Schedule 40 Foam core pipe is the ideal pipe for bathroom fan venting. This type of piping is non-toxic, easy to install, and is code compliant. The PVC pipe fittings can be safely cemented and sealed, preventing any water that might collect in the pipe from leaking and causing water damage.
An added advantage is that PVC Schedule 40 Foam Core has a lightweight cellular core and is co-extruded. This means that while the walls of the pipe are solid PVC, the inner core is foamed (or cellular) PVC, making the pipe lighter.
Certified cellular foam PVC piping should have the certification number ASTM F 891 stamped on the pipe.
The PVC piping needs to be as straight or as rigid as possible. Bends in the pipe increase static resistance causing problems for the fan. If your designs include bends, use long-sweeping elbows rather than short bends to improve circulation.
Our informative guide, How Bathroom Fans Should Be Vented: A Complete Guide, provides more information on venting bathroom fans.
Does PVC Pipe Need to Be Insulated
PVC pipe should be insulated when used as a ducting material for bathroom fans. Insulation prevents moisture build-up and condensation on the inside and the outside of the pipe.
In warmer climates, the indoor temperates are generally kept low, which causes condensation to form on the outside of the duct pipes. Water can drip from the pipes causing moisture damage to the fittings and the ceiling.
When hot, moist air is vented through the duct in colder climates, it connects with the cold duct, and condensation forms inside the pipes. The water could eventually drip down, causing unseen damages.
An uninsulated duct could cause a bathroom fan to drip, causing unsightly brown stains around the fan.
This Is Why PVC Pipe Is Good for Venting
PVC piping is an excellent material to use for venting your bathroom fan as long as the correct type of pipe is used. PVC creates a better seal than metal, so you won’t experience any problems with leakage as you could with using metal ducting pipes.
According to various online sources, PVC pipes are the material of choice for ducting. Here’s why:
- PVC is durable and safe. The lifespan of PVC piping is expected to be 100 years or more, so it could outlast the fan itself.
- PVC foam core pipe is less rigid and lasts even longer than standard PVC pipe.
- The core inside the PVC foam core pipe insulates sound, muffling any noises from the vent.
- Tightly sealed, leak-free fittings prevent water loss and costly water bills.
- PVC is free from bio-film contamination. Bio-film breeds bacteria and mold, which will not breed in an adequately sealed PVC pipe.
- Fewer materials are used for the manufacture of foam core PVC, making it more cost-effective.
- PVC is a lightweight material that does not rust, corrode or scale.
- PVC is a low carbon plastic making it recyclable and sustainable.
PVC Pipe Has Drawbacks as a Ducting Material
Even though PVC piping is our material of choice for ducting material, it is not perfect. PVC piping does have a few disadvantages and limitations which could influence your choice of materials:
- PVC pipes are not flexible. Maneuvering the pipes through the ceiling or roof can be difficult, limiting your installation and placement options.
- Once PVC pipe is cemented to the fan, it is difficult to remove and will need to be cut off should you need to replace any components or relocate the fan or the vent. The PVC pipe might not be salvageable and may need to be replaced with a new one, adding additional costs to the repair or relocation of the fan.
- PVC piping can become brittle in lower temperatures and is prone to cracking when exposed to freezing or colder temperatures over an extended period of time.
- PVC piping has different rated strengths. If the wrong strength is accidentally used for a particular job, the outcome might not be as expected. The pipe might not last as long, and the installation could fail.
How to Connect PVC Pipe to Bath Exhaust Fan
Before you connect any piping to your bath exhaust fan, check the building code requirements and install according to the manufacturer’s directions.
- PVC pipe
- Heavy-duty clear PVC cement
Connect the PVC pipe to the bath exhaust fan using PVC heavy-duty cement. This forms a secure water-tight bond and a properly seated joint with the fan exhaust. The best glue to use for this is a specialized PVC cement that uses chemicals to weld the PVC pipe to the exhaust vent port.
You will need to cement the pipe in place to ensure that moisture does not leak from the join and cause moisture damage to your ceiling or roof.
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