Can You Safely Vent a Dryer Through the Roof? (Avoid Fire)


It’s not always practical to vent a clothes dryer through an outside wall, so is it safe to vent your dryer through the roof?

You can vent a dryer through the roof, but it must be installed according to the International Residential Code. Venting through roofs is a potential fire hazard due to the build-up of lint, which is why it requires routine professional cleaning. If there is access, it’s better to vent a dryer through an outside wall.

In this article, I’ll show you:

  • Pros and cons of venting through the roof
  • How to comply with building code
  • What’s involved in order to keep the roof vent clean
  • How to install a dryer vent on your roof
Can You Put Furniture Over a Vent? ...

Pros and Cons of Venting a Dryer Through the Roof

Pros

  • Building Codes – The code forbids many forms of venting, though roof venting is often the most compliant.
  • Aesthetics – It is possible to install a roof vent, which is in keeping with your neighborhood and disappears into the colors of your roof.
  • Duct Length – The roof is often the shortest distance to the outdoors and means less ducting pipe.
  • Rodents – More difficult for rodents to make their way into a roof vent.
  • Less Complex – Fewer turns and a simple case of going straight up.
  • Protected – Roof vents are less obvious and less prone to accidental breakages than a ground-level vent.

Cons

  • Condensation – The ducting may have to go through a cold attic, which will condense the vapor in the duct. The resulting droplets will roll back down the pipe and give lint something to cling to.
  • Leaks – This means making a hole in your roof, which may start a leak even if you think you have sealed it.
  • Cleaning – Harder to clean, and the building codes may require that they be cleaned annually.

What Is in the Code for Venting a Dryer Through a Roof?

International Residential Code (IRC) Section M1502 is a specific chapter on the correct way to deal with clothes dryer exhausts. Most clauses in the dryer code are there to ensure the safety of both the occupants of the home and those living nearby.

Here are some examples of the IRC’s dryer vent clauses:

  • Directions – Follow the manufacturer’s instructions on how to install the ducting and the type of vent cap locations to avoid.
  • Standalone -The ducting for a dryer should not connect to any other venting system in the home, such as those of bathrooms or kitchen extractor fans.
  • Outside – Ducting must direct all exhaust to the outside. The exception is when the dryer is ductless.
  • Prevent Blowback – The exhaust vent must be further than 3 feet away from any other entry point, such as a door, window, or another vent.
  • Diameter – The code specifies that at no point in the ducting should the diameter of the pipe be smaller than four inches. The duct also needs to be at least 27-gauge metal (thicker than 1/64 inch).
  • Support – The ducting should have some form of support every 12 feet.
  • Max. Length – No dryer ducting should exceed 35 feet in length.

How Do You Keep Roof Vents Clean?

Before installing a roof vent for your dryer, you will first want to consider the following points on what this means for maintenance.

Roof Dryer Vent Cleaning Cost

The cost ranges from free, if you do it yourself, to over $100 to bring in a professional. The greatest benefit of using a professional is not needing to take the personal risk of clambering up onto your roof.

Cleaning a Dryer Vent Without Getting on the Roof

A less effective way of cleaning the dryer vent is to use a vacuum cleaner at the bottom of the duct. Detach the dryer from the end of the duct, then put the vacuum pipe inside.

Then try to seal up around, between the duct and vacuum with an old cloth. This will suck through a lot of material, but it will not remove stubborn lint that is stuck to the inside of the duct or in the vent cap.

Roof Dryer Vent Keeps Getting Clogged

The most common reason is something stuck in the lint trap, either dirt or an object. After eliminating the trap as an issue, check the vent flaps. The flaps may be worn, blocked from the outside, or broken.

Roof Vent Cleaning Service

A professional will clean every part of the duct and get onto the roof to clean the vent cap. Professional duct cleaners will use specialist tools to sterilize the ducting. A professional will certify the cleaning in case you need it as proof for your regulator.

How to Install a Dryer Vent on Your Roof

With a few simple tools and some basic instructions, you can have your dryer venting through your roof in no time at all.

Tools and Materials List

  • Pencil
  • Drill
  • 1/4-inch drill bit
  • 4-inch hole saw for a drill or reciprocating saw
  • Hammer or screwdriver
  • Roofing sealant
  • Roofing tar
  • Foil tape
  • 1-inch screws or nails
  • 2 × jubilee clips
  • 4-inch metal duct elbow
  • Roof vent cap
  • 4-inch metal ducting
  • Ducting insulation
  • Tin snips

Step-by-Step Guide

  1. Location – Once you have the dryer in position, plan out the shortest route to the roof. Each 90-degree bend is like adding 5 feet to the duct, so try to run the duct straight up from the first bend at the back of the dryer.
  2. Mark – Outline where you are going to cut the hole through the roof. Drill a pilot hole in the roof through the middle of the duct outline to see where the vent will come out.
  3. Shingles – Get onto the roof and remove the shingles from around where the vent will sit.
  4. Hole – Use a reciprocating saw, or a hole saw, to cut through the roof so that you can fit the vent cap through.
  5. Install – Install the vent, then paint roofing tar between the vent and the roof. Use 1-inch screws or nails to secure the vent.
  6. Seal – You can also seal the skirting to the roof with foil tape, then paint more tar over the tape to seal the roof to the tape. Replace the shingles and cut them to fit around the vent cap.
  7. Duct – Go back to the underside of the roof and connect the duct to the vent cap. Wrap foil tape around the dryer vent ceiling connection and then secure them with a jubilee clip.
  8. Insulate – Insulation will prevent the water vapor in the exhaust from condensing onto the cold metal. This is even more important if the duct first travels through an attic.
  9. Connect and Secure – Connect the duct to the back of the dryer with foil tape and a jubilee clip. And make sure that the weight of the ducting is supported if it spans more than 12 feet.

Best Roof Dryer Vent Cap

Broan Roof Vent KitOpens in a new tab.

This complete set gives you all the parts you need to install a professional-looking roof dryer duct. The low profile of the cap helps it to combat high winds and stay out of sight. The cap also has a wide skirt to give you more area to seal to the roof and prevent leaks.

  • Included: 8-foot 4-inch duct, 2 × zip-ties clips, 4-inch connector, sealant foam.

Vent Systems 4-inch Round Roof CapOpens in a new tab.

Simple but effective, this 4-inch galvanized vent cap allows for venting in all horizontal directions and can be elevated to be out of the snow. A simple rubble gasket seals the connection to the ducting, which makes this cap easier to remove for regular cleaning.

  • Included: 4-inch duct cap.

Graham Walsh

I want to share everything I know about home improvement in order to help you. Whether you're a home enthusiast or an industry professional, I have the information that you need.

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