Washington Park, a ten-story apartment building, was originally constructed in 1964 and converted to condominiums 35 years later.  During the conversion, one contractor was hired to replace all the existing single pane aluminum windows with double pane vinyl windows. This was difficult because the original exterior of the building was considered historic by the City of Portland, requiring the appearance of the stucco-like material called ‘Marble-crete’ to remain unaltered.

The contractor engineered a way to retrofit the windows without damaging the Marble-crete, and prepared a mock-up and demonstrated the process. The retrofit was approved by the window manufacturer and developer, and completed by the contractor.  Later the Homeowners Association (HOA) filed complaints against a number of the conversion upgrades, including the retrofit windows that were installed.

During our investigation, we observed the difficultly of opening the windows. We documented the windows and performed invasive testing from the interiors, window water testing and air balancing tests.  After reviewing and analyzing the data, we determined that when the old single pane aluminum windows, which leaked air, were replaced with new windows, the air balancing dynamic of the building had changed.  The interior of the building, which had a strong system to exhaust air, did not have an adequate make up air system, causing the interior to have a fairly large negative air balance from the exterior.

This condition of interior to exterior air pressure to pull/push on the windows caused them to fit so tightly to the interior track that the rubbing friction prevented them from sliding as easily as they were manufactured to do.   The negative air pressure was so great that in some areas it was pulling moisture through minor pin holes where it would not happen otherwise.

The case ended up going to trial, where with graphics, demonstrative exhibits and expert testimony we presented the situation, and the window installer was awarded a 100% defense verdict.