FireApproved

United States / Build / Vents

Vents

Program and model No adopted WUI code we can source here. IBHS Wildfire Prepared asks for the inspection measures, and the 2024 IWUIC model says the same floor.

National floor. A ZIP opens the same question at a place where a sourced instrument exists.

Find what applies near you

Enter a ZIP before browsing the complete evidence. Matching, inherited, and place-neutral records will move first; other places and unmapped application rows will fold into expandable groups. Nothing is removed. All 3 state rule sections remain available.

The rule

Model code “noncombustible corrosion-resistant mesh with openings not to exceed 1/4 inch (6.4 mm)”

2018 IWUIC Class 1–2 vent mesh. The unamended 2018 IWUIC specifies noncombustible corrosion-resistant mesh with openings no larger than one-quarter inch for Class 1 and Class 2 vents.

Products matching the model-code floor

Model code Product matches below are limited to vents and trace to the named requirement.

Additional products matching the voluntary program

Voluntary program Product matches below are limited to vents and trace to the named requirement.

How sourced instruments differ

Three paths, not three names for one product. A listed 8165 assembly is an ASTM E2886 record. Mesh is a size rule. A dryer flap is a lint path. Oregon R327, California CWUIC, Colorado CWRC, and IBHS do not always pick the same path. CWRC 403.4 is attic, rafter, and underfloor, not a dryer-vent rule.

Oregon R327 where adopted

Listed assembly
R327.3.2 allows vents designed to resist burning embers and flame. Underside of eaves still needs the official’s accepted manufactured vent or a 12-foot opening.
Metal mesh
R327.3.2 names 1/16–1/8 inch mesh for attic, soffit, rafter, and underfloor openings. It is not a substitute for the eave-underside rule.

California CWUIC

Listed assembly
Specifiers often pull an OSFM 8165 model. Listing is still voluntary for most WUI products.
Metal mesh
Prescriptive mesh cover appears in CAL FIRE home-hardening. CWUIC-mapped jobs often use the listed-assembly path. Confirm the project scope.

Colorado CWRC

Listed assembly
CWRC 403.4.1 is one Class 1 path: listed vents tested to ASTM E2886. Class 2 includes that rule. Confirm the local ordinance.
Metal mesh
CWRC 403.4.2 is the other Class 1 path: noncombustible corrosion-resistant mesh with openings not more than 1/8 inch for enclosed attics, rafter spaces, and underfloor. It does not name 1/16 inch. Confirm the local ordinance.

Where this answer differs

6 sourced rows

  • Model code 2018 IWUIC Class 1–2 vent mesh — The unamended 2018 IWUIC specifies noncombustible corrosion-resistant mesh with openings no larger than one-quarter inch for Class 1 and Class 2 vents.
  • Model code 2021 IWUIC Class 1–2 vent mesh — The unamended 2021 IWUIC specifies noncombustible corrosion-resistant mesh with openings no larger than one-quarter inch for Class 1 and Class 2 vents.
  • Model code IWUIC vent mesh — The unamended 2024 IWUIC model code specifies noncombustible corrosion-resistant vent mesh with openings no larger than one-eighth inch as a prescriptive path.
  • Voluntary program IBHS Base forced-air vent closure — The current IBHS Base standard calls for a functional louver or flap on forced-air vents such as dryer and central-vacuum exhausts.
  • Voluntary program IBHS Base vent mesh — The 2025 IBHS Base standard permits a prescriptive vent-covering path using documented noncombustible, corrosion-resistant mesh with openings no larger than one-eighth inch.
  • Voluntary program IBHS Plus metal forced-air vent closure — The current IBHS Plus standard adds noncombustible construction to the Base functional-closure requirement for forced-air vents.