With home maintenance, some shortcuts can lead to big problems. One of those shortcuts is venting your clothes dryer into the attic. It may seem convenient, but it violates building codes in most cities because of its hazards.
Let’s further explore why venting your dryer in the attic is a bad idea.
What Potential Issues Could Arise With Venting a Dryer in the Attic?
As traditional clothes dryers run, they push out hot, moist air filled with lint. Venting the air into the attic can create a perfect storm of problems that compromise safety, structural integrity, and even your health.
Lint is highly flammable. Just one spark from the dryer or electrical system could cause the dryer or system to burst into flames, and in an attic, the fire could spread down to the rest of your home.
According to National Fire Prevention Association (NFPA) reports, there are thousands of dryer fires each year, and lint buildup causes about a third of them. Even the slightest breach in protocol could transform your attic from a peaceful storage space to a tinderbox in waiting.
When moist air from a dryer enters an attic, it can severely damage your home’s structure over time. The excess humidity can lead to these dangerous, sometimes yucky problems:
- Rot in roof trusses and decking
- Mold and mildew growth
- Insulation deterioration
- Warped wooden structures
- Metal fastener and component corrosion
Beyond structural damage, moisture accumulation can impact your home’s electrical systems by corroding wiring. That can both disrupt your household activities and further increase the risk of a fire.
Venting a dryer into the attic can affect your home’s air quality. As exhaust from your dryer circulates, it increases humidity levels and puts more lint in your household air. If mold grows from locked-in moisture, its spores can circulate through the air. Each problem can be a nightmare if you have allergies or respiratory problems.
How To Vent Your Dryer Properly
The only safe and code-compliant way to vent a dryer is to your home’s outside. This guarantees the expulsion of all the heat, moisture, and lint from the house, where they won’t cause further problems. It also makes the dryer more efficient and lowers your energy bills.
There are two main options for exterior venting: outside wall venting and roof venting. Each method has a set of procedures and considerations, and you’ll have to choose based on your home’s layout.
If your laundry room has an outside wall, cut a 4-inch hole and install a standard dryer vent hood with a damper. Don’t cut through electrical wires, pipes, or structural framing. Use rigid metal ductwork to connect the dryer to the vent hood.
You may need to vent through the roof if you don’t have exterior wall access from your laundry room. This method is a bit more complex but can be just as effective.
Choose a location on a sloped surface so moisture can run off properly, and install a specialized roof vent cap to prevent leaks. Run rigid metal ductwork, with proper support and insulation, from the dryer to the roof cap.
Seal all roof penetrations thoroughly to prevent leaks, and caulk around the vent. You don’t want external moisture to enter your home through residual gaps.
Proper Dryer Vent Installation
Whether you’re venting through a wall or your roof, follow these tips for proper installation:
- Use rigid metal ductwork. Use only rigid metal, never flexible plastic or foil vents. Metal ductwork is less prone to punctures or collapses. Never use flexible plastic or foil vents, which are less durable.
- Straight and short wins the race. Keep the vent run short and straight, ideally under 35 feet. Longer vent runs increase the chance of lint buildup and blockages.
- Cut down on elbows. Each 90-degree turn reduces airflow and puts more strain on the dryer motor. It’s, therefore, best to minimize the use of elbows.
- Use tape to seal. Seal joints with metallic HVAC tape—not screws, which can catch lint. Proper sealing techniques help maintain airflow while also preventing potential fire hazards.
- Install a damper. See that the exterior vent hood or outlet has a functioning damper to prevent backdrafts, stop pests, and maintain temperature control in your home.
- Use booster fans as needed. Longer vent runs or installations with multiple turns may require a duct booster fan to maintain airflow.
- Don’t dent the vent. Don’t use dented ducts for a dryer vent installation since they may harm healthy airflow.
Dryer Vent Safety Tips
How you use your dryer and build your vent system impacts your safety. Follow these tips for the most risk-free experience:
- Clean the lint trap. Always clean the lint trap when using your dryer. It’s a simple habit that prevents fires and protects the appliance’s lifespan.
- Inspect outlets and hoods regularly. Debris or snow can impede airflow through outlets and vent hoods. Inspect them at least twice a year.
- Clean your vents annually. Clean the entire vent system at least once a year. Even if you always clean the lint trap, there can still be clogs of lint that reduce airflow and increase fire risk. You can do the job yourself or hire a professional dryer vent cleaning company—according to Angi, the service can cost anywhere from $103 to $184.
- Keep flammable materials away. Flammable objects such as laundry detergent, cleaning supplies, and loose clothes can pose fire risks, so keep the area around your dryer clear of them.
- Never leave the dryer unattended. Don’t run your dryer when no one’s home or while you’re asleep. Constant supervision will let you intervene if any issues arise during a cycle.
How Much Does New Dryer Venting Cost?
The exact cost to install or replace dryer vents varies with the vent system’s location and complexity. However, Angi says most jobs cost between $140 and $600.
While the price tag may seem expensive, view it as an insurance policy. Preventive measures to vent your dryer properly will allow you to avoid the excessive costs of fire damage cleanup, mold remediation, or appliance repair.
FAQs About Venting Dryers
How do I clean my dryer vent?
Detach the dryer vent where it connects to the dryer and use a dryer vent brush to clean lint from the entire length of ductwork—vacuum loose lint with a hose attachment. Clean your vents at least once a year. If you’re uncomfortable with this process, ask your HVAC contractor if they provide this service when performing your annual HVAC tune-up.
Can I vent my dryer into the garage?
No, venting a dryer into the garage is dangerous, just like venting into the attic. Always exhaust dryers outdoors.
What are the signs of a clogged dryer vent?
Signs include clothes taking longer to dry, hot air escaping the dryer cabinet, and lint accumulating around the vent hood outdoors. A professional can confirm if there’s an obstruction in your vent.
What is the maximum length for a dryer vent?
Check your owner’s manual, but don’t exceed 35 feet in total developed length. Calculate length, adding 5 feet for each 90-degree elbow. Maintain velocity with rigid metal ductwork.
How do I install a dryer vent through the roof?
Use a vent designed for roof venting. Install on a sloped roof surface. Use silicone caulk to seal around the pipe penetration through the roof deck.
Can I vent two dryers together?
No. Each dryer needs its own 4-inch diameter vent from the machine to the outlet. The only exception is a common manifold at the very end.
