Installation of windows and exterior doors that are provided with an integral exterior flange and designed to be installed on the exterior of essentially flat lock-seam metal siding without a head or sill flashing, in exterior walls with cladding assemblies to which Subsection 9.27.3. applies [see Article 9.27.1.1. for application of Subsection 9.27.3.].

To limit the probability of precipitation or meltwater ingress into wall assemblies at the junction between windows or doors and the adjoining wall.

This is to limit the probability of:

• compromised thermal performance of components intended to provide resistance to heat transfer, which could lead to an inadequate control of the temperature of interior spaces or relative humidity,
• the generation of pollutants from biological growth or from materials that become unstable on wetting, or
• deterioration, which could lead to compromised integrity of exterior walls or elements protected by exterior walls.

This is to limit the probability of:

• negative effects on the air quality of indoor spaces,
• the inadequate thermal comfort of persons, and
• contact with moisture.

This is to limit the probability of harm to persons.

To limit the application of Sentence 9.27.3.8.(3), Sentence 9.27.3.8.(4) and Sentence 9.27.3.8.(5), where windows and exterior doors are designed to be face-sealed to the exterior surface of the cladding.