Home / Requirements / 2021 IWUIC Class 1–2 vent mesh

2021 IWUIC Class 1 and 2 quarter-inch vent-mesh path

The unamended 2021 IWUIC specifies noncombustible corrosion-resistant mesh with openings no larger than one-quarter inch for Class 1 and Class 2 vents.

This record covers documented mesh size, material, and vent role only. The 144-square-inch opening limit, free area, installation, prohibited soffit and eave locations, alternative approval, official map, assigned class, project scope, and local amendments remain checks.

code · Jurisdictions adopting unamended 2021 IWUIC Sections 504.10 and 505.10 · Last verified 2026-08-27 · JSON (CC BY 4.0)

Published requirement text

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

2021 International Wildland-Urban Interface Code, Sections 504.10 and 505.10 — International Code Council

Where this instrument is documented

Instrument iwuic-2021.

Set a location to read how this instrument lands where you are.

Place	Force	Reach	Dated	Checks open	Source
Pennsylvania	active application documented	statewide	effective 2026-01-01	4	34 Pa. Code § 403.21 Uniform Construction Code

Each place page carries that place's boundary, project scope and open official checks in full; this page's JSON twin carries them per application.

Machine-readable constraints

Attribute	Operator	Value	Unit
assemblyRole	in	foundation-vent–retrofit-mesh
meshSizeInch	lte	0.25	inch
corrosionResistant	eq	true
noncombustible	eq	true

Products with documented matching attributes

Open the Build rules that quote this requirement

Product	Category	Status	Documented match evidence
FireStorm EmberMesh roll	vents	Attribute match	4 cited fields Mesh opening: 0.0657 in Assembly role: retrofit mesh Corrosion resistant: Yes Noncombustible: Yes
Wildfire Defense Mesh 75 black roll	vents	Attribute match	4 cited fields Mesh opening: 0.1072 in Assembly role: retrofit mesh Corrosion resistant: Yes Noncombustible: Yes

Sources

2021 International Wildland-Urban Interface Code, Sections 504.10 and 505.10 — International Code Council (official). Accessed 2026-08-27.

2021 IWUIC Class 1 and 2 quarter-inch vent-mesh path. FireApproved. https://fireapproved.com/requirements/iwuic-2021-class-1-2-quarter-inch-vent-mesh/. Last verified 2026-08-27.