Dryer vent cover: what the code and the dryer makers require
An outside dryer vent cover must have a backdraft damper and no screen where the 2021 International Residential Code is adopted (section M1502.3), and its outlet must give an open area of at least 12.5 square inches (M1502.3.1). Whirlpool's 2009 electric dryer installation instructions (W10267633) recommend a louvered or box hood, call an angled hood acceptable, and say not to use a hood with a magnetic latch. HomeGuide puts the cost to replace a dryer vent cover at $50 to $100, with the cover alone at $5 to $10.
| What the outside cover needs | Who says it | Wording |
|---|---|---|
| A backdraft damper at the duct termination | 2021 IRC, M1502.3 | "shall" |
| No screen at the duct termination | 2021 IRC, M1502.3 | "shall not" |
| An undiminished passageway with at least 12.5 square inches of open area | 2021 IRC, M1502.3.1 | "shall" |
| A covering that keeps out rain, snow and dirt, but no wire screen or cloth | U.S. Fire Administration | "should"; "Do not" |
| Louvered or box hood recommended; angled hood acceptable | Whirlpool 2009 electric dryer installation instructions (W10267633) | "Recommended"; "Acceptable" |
| At least 12 inches from the ground or anything in the path of the exhaust | Whirlpool; GE | "must" |
| No magnetic latch on the hood | Whirlpool 2009 electric dryer installation instructions (W10267633) | "Do not use" |
| A dampered wall cap with the opening pointed down | GE specification sheet (created 11/03) | "should"; "must" |
| The flap opens when the dryer is running | NFPA; U.S. Fire Administration | "Make sure" |
The code rules for a dryer vent cover
The 2021 International Residential Code, where your city or state has adopted it, sets the rules for the outside end of a dryer duct in section M1502.3: "Exhaust duct terminations shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination." The same section says terminations shall follow the dryer manufacturer's installation instructions.
Section M1502.3.1 adds the size rule: the passageway of the exhaust terminal "shall be undiminished in size and shall provide an open area of not less than 12.5 square inches." The 2024 edition of the IRC carries the same damper, screen and 12.5 square inch wording. State versions can differ: North Carolina's 2018 residential code version of M1502.3 says screens shall not be installed at the duct termination or weather cap outlet, and that an exhaust duct shall terminate not less than 12 inches above finished grade, with an exception: a lower termination needs an areaway with a cross-sectional area of not less than 200 square inches. The version your building department enforces is the one that counts.
Our dryer vent installation guide covers the rest of the termination rule, including the 3-foot distance from openings into the building.
Should dryer vents have screens?
No. The 2021 IRC says "Screens shall not be installed at the duct termination" (M1502.3). The U.S. Fire Administration's clothes dryer fire report says: "Outside wall dampers should have a covering that will keep out rain, snow, and dirt. Do not, however, use wire screen or cloth as these can collect lint and clog areas of the dryer vent."
That is the check to run on any product sold as a dryer vent bird guard or pest guard. Where that code is adopted, M1502.3 says: "Screens shall not be installed at the duct termination." Whether a given guard counts as a screen is for your building department to decide. It also has to leave the outlet undiminished, with at least 12.5 square inches open (M1502.3.1). Whirlpool's venting specifications say Whirlpool does not provide approvals for third-party vent accessories that are not licensed by Whirlpool Corporation. If you are unsure about a guard, ask your local building department before you fit it.
Dryer vent hood types: louvered, box and angled
Whirlpool's electric dryer installation instructions (W10267633) show three hood styles. A louvered hood and a box hood are listed as recommended; an angled hood is listed as acceptable. The same instructions say an exhaust hood should cap the vent to keep rodents and insects from entering the home, must be at least 12 inches from the ground or any object that may be in the path of the exhaust (flowers, rocks, bushes, the snow line), and says: "Do not use an exhaust hood with a magnetic latch."
The hood style changes how long the duct may be. Whirlpool's vent system chart for these models allows a longer rigid metal run with a box or louvered hood than with an angled hood:
| 90-degree elbows | Box or louvered hood | Angled hood |
|---|---|---|
| 0 | 64 ft | 58 ft |
| 1 | 54 ft | 48 ft |
| 2 | 44 ft | 38 ft |
| 3 | 35 ft | 29 ft |
| 4 | 27 ft | 21 ft |
Whirlpool says not to use vent runs longer than the chart allows, because longer systems shorten the life of the dryer and reduce performance. Your own dryer's instructions set the numbers for your model, and the code sets its own duct length limits; see how long a dryer vent can be.
GE's specification sheet for its DLSR483GE gas dryer (marked "Specification Created 11/03") says exhaust ducts should be terminated in a dampered wall cap to prevent back drafts and bird nesting, and the wall cap must be at least 12 inches above the ground or any other obstruction with the opening pointed down. It says other terminations, such as louvered wall boxes, are acceptable provided they are equivalent to a 4-inch opening dampered wall cap.
How do you keep birds out of dryer vents?
The dryer makers point to a dampered cap and regular checks. GE says a dampered wall cap prevents back drafts and bird nesting, and its check-vent support page says to make sure there is not a bird or other wildlife nest inside the duct or hood. Maytag says birds and rodents may find dryer vents a warm, sheltered spot for nests, and that regularly checking the exterior vent cover can help prevent these unwanted visitors. HomeGuide lists keeping birds and other pests from nesting in the vent as one reason a cover is needed.
A nest is a fire risk, not only a nuisance. The USFA says blockage in dryer exhaust vents can occur from the nests of small birds or other animals, that a compromised vent will not exhaust properly, and that overheating and a fire may follow. Its list of dryer safety tips says to check periodically that nests of small animals and insects are not blocking the outside vent. Our list of signs of a clogged dryer vent covers what to look for.
How to clean exterior dryer vent covers
Whirlpool's venting specifications recommend an annual inspection of the exhaust system for single-family use. Its inspection steps cover the hood:
- Disconnect the duct. Take the exhaust duct off the dryer and off the exhaust hood outside the building (Whirlpool).
- Remove lint from the duct and the hood. Whirlpool says lint may collect in the exhaust hood so that the flappers or louvers will not open or close completely.
- Check the flap or louvers. After cleaning the hood, check that the flapper or louvers move freely (Whirlpool). GE says the damper flaps of the wall cap should move freely when the dryer is operating.
- Reassemble and test. Put the duct and hood back together with secure joints, run the dryer, and check that the exhaust air is not obstructed and there are no leaks; seal any leaks found (Whirlpool).
Between cleanings, Whirlpool's product help says to check that the vent hood on the outside of the house is not clogged or blocked by landscaping. NFPA's dryer safety tips say to check that the outdoor vent flap is not covered by snow and that it opens when the dryer is operating. For a hood you cannot reach from the ground, see cleaning a dryer vent from outside.
Dryer vent cover replacement
HomeGuide puts the cost to replace a dryer vent cover at $50 to $100 on average, depending on the type and complexity, and the cover alone at $5 to $10. It says most vent covers attach directly to the vent pipe with caulking around the rim to seal it. Whirlpool's instructions say to seal the exterior wall opening around the exhaust hood with caulking compound and to secure the vent to the hood with a 4-inch clamp, with the vent fitting inside the hood.
The step-by-step swap is in our guide on how to replace an outside dryer vent. Before you buy, check the new hood against the table at the top of this page: a damper, no screen, at least 12.5 square inches open, and a style your dryer's instructions accept.
If the hood keeps filling with lint, the duct behind it may need a dryer vent cleaning rather than a new cover. To have a company check or replace your cover, use the form below and we will send your request to a company that serves your ZIP code.
Dryer vent covers: common questions
What is a backdraft damper for dryer vent?
Should outside dryer vent be open?
What is the best dryer vent cover?
Magnetic dryer vent cover
Can birds get in dryer vent?
Sources
- International Code Council, 2021 International Residential Code, section M1502: codes.iccsafe.org
- International Code Council, 2024 International Residential Code, chapter 15, section M1502: codes.iccsafe.org
- 2018 North Carolina State Building Code: Residential Code, Chapter 15: codes.iccsafe.org
- U.S. Fire Administration, "Clothes Dryer Fires in Residential Buildings (2008 to 2010)", August 2012: usfa.fema.gov
- NFPA, "Clothes dryer safety" tip sheet: nfpa.org
- Whirlpool, "Electric Dryer Installation Instructions" (W10267633A): whirlpool.com
- Whirlpool, "Dryer venting specifications" (W11688180A): whirlpool.com
- Whirlpool Product Help, "Whirlpool Dryer Check Vent Light Is On": producthelp.whirlpool.com
- GE Appliances, DLSR483GE gas dryer specification sheet, "Specification Created 11/03": geappliances.com
- GE Appliances, "Dryer: Check Vent Sensor Alert": geappliances.com
- Maytag Product Help, "How to tell if your Maytag Dryer Vent may be Blocked or Restricted": producthelp.maytag.com
- HomeGuide, dryer vent installation cost, page dated January 5, 2026: homeguide.com