DEPARTMENT OF HOMELAND SECURITY

OFFICE OF THE BUILDING LAW COMPLIANCE OFFICER

The building law compliance officer, pursuant to the authority granted under IC 22-15-2-6(b) and IC 22-13-5, has developed this written interpretation of a building law. Pursuant to IC 22-13-5-4, this written interpretation of a building law is binding upon all counties and municipalities.

This written interpretation will continue to bind all counties and municipalities until the earlier of the following:

(1) The general assembly enacts a statute that substantively changes the building law interpreted or voids the written interpretation.

(2) The fire prevention and building safety commission adopts a rule under IC 4-22-2 to state a different interpretation of the building law.

(3) The written interpretation is found to be an erroneous interpretation of the building law in a judicial proceeding.

(4) The office of the building law compliance officer publishes a different written interpretation of the building law.

Indiana Residential Code (675 IAC 14-4.3) Section R703.7.4.2 requires an air space behind stone and masonry veneer wall covering that is applied over a backing of wood studs or sheathing material, and, if the wall sheathing is not water-repellent, requires a weather-resistant sheathing paper or the equivalent to cover the sheathing. Section R703.7.4.3 allows the air space required by Section R703.7.4.2 to be filled with mortar and requires weather-resistant sheathing paper or the equivalent to cover water-repellent or non-water-repellent sheathing.

The first sentence of Section R703.7.4.2 requires at least a ¾-inch air space between masonry veneer and the sheathing material. The first sentence also recognizes that a weather-resistant sheathing paper or the equivalent is required to cover non-water-repellent sheathing. Mortar that encroaches into the air space or even makes incidental contact with the sheathing or the sheathing paper or equivalent is acceptable if the air space cavity can drain and dry.

The second sentence of Section R703.7.4.2 allows the deletion of the weather-resistant sheathing paper or the equivalent where water-repellant sheathing material is applied in accordance with the manufacturer's installation instructions. Mortar that encroaches into the air space or even makes incidental contact with the sheathing is acceptable if the air space cavity can drain and dry.

Section R703.7.4.3 allows the ¾-inch air space to be filled with mortar and requires weather-resistant sheathing paper or the equivalent to cover the sheathing or studs. This provision conflicts with the requirement of Section R703.7.4.2. The interface between the mortar and weather-resistant membrane is not likely to effectively drain and dry in this situation. General Administrative Rules Section 675 IAC 12-4-8 requires that where, in any specific case, different sections of the rules of the commission specify different materials, methods of construction or other requirements, the most restrictive shall govern. Provision of the air space in accordance with Section R703.7.4.2 is the most restrictive and is the only acceptable alternative.

In addition, the ¾-inch air space required by Section R703.7.4.2 is a nominal dimension. Encroachment of mortar into the space, incidental contact with sheathing or weather-resistant membrane by mortar, and bowing of wall stud or plate material may cause variation in the dimension and are acceptable if the air space will drain and dry.

An equivalent to weather-resistant sheathing paper is a material for which an acceptable evaluation report has been issued that states equivalency in accordance with Section R703.2.

DIN: 20070919-IR-290070567NRA

Composed: May 02,2024 8:28:01PM EDT

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