How to Use This Calculator

Understanding the Simulated Durability Analysis Results

WUFI Hygrothermal Modeling and Field Experience Rating
This represents the result of a combined analysis of field experience and comprehensive WUFI analyses on the selected wall assembly in each of the 5 climate conditions:

Dark Green: HIGH PASS Field: Good experience under wide range of conditions Physics: Well understood physics and sound basis for design Hygrothermal Modelling: Simulations support field experience and expectations from physics

Light Green: PASS Field: Good experience under normal conditions Physics: Well understood physics; expected to  be slightly sensitive to details and workmanship Hygrothermal Modelling: Simulations support field experience and expectations from physics

Yellow: CONDITIONAL PASS Field: Acceptable experience under  normal conditions; more sensitive to details, workmanship, and microclimates Physics: More complex physics, expected to be more sensitive to details and workmanship Hygrothermal Modelling: Field experience and physics can only be explained by expert modellers

Orange: CONDITIONAL FAIL Field: Demonstrated to be risky in certain situations Physics: More complex physics, expected to be VERY sensitive to details and workmanship Hygrothermal Modelling: Field experience and physics can only be explained by expert modellers

Building Codes have air barrier and rain intrusion requirements that are assumed to be complied with.  Failure to meet code requirements can result in walls that are not durable.

It is important to note that all the assemblies were simulated assuming no air leakage and no water intrusion/leakage.  As a result, the WUFI durability simulations do not consider the limited drying potential associated with the use of low permeance sheathing materials when combined with poor air barrier installation and flashing details.

Please see WUFI Assumptions for more details.

Outboard to Inboard Ratio Compliance
This scale represents the result of an outboard to inboard analysis on the wall assemblies using low permeance exterior sheathings:

Green indicates that the wall meets the climate’s required minimum ratio

Red indicates that the wall does not meet the climate’s required minimum ratio and the outboard sheathing’s permeance must be examined to verify Code compliance