Background

The 157,000 SF, six-story building is clad primarily with brick veneer with metal panels in localized areas.

Construction of the building was in progress when Rimkus was asked to evaluate several aspects of the work, including some components of the design. The envelope design was fairly conventional with steel-stud framing with batt insulation, gypsum sheathing, rigid insulation board and brick veneer with gypsum drywall on the interior.

Services:

Rimkus was asked to provide services on four individual assignment pertaining to the following:

Insulation and Weather Resistant Barriers (WRB)

• Determine whether the one rigid foam insulation product that was specified was the only one that met requirements for thermal performance and flame spread, for purposes of not having a closed specification for bidding;
• Determine whether mineral fiber insulation had to be installed in lieu of rigid foam insulation behind metal panels, due to code requirements for fire resistance;
• Determine whether an impermeable or semi-permeable WRB was appropriate for the construction indicated.

Insulation Facing, Latex Paint, and Unspecified Insulation-product Installation by a Subcontractor

• Determine whether foil-faced insulation or Foil Scrim Kraft (FSK)–faced insulation was required at areas of exposed insulation;
• Evaluate the permeability of the specified interior latex paint and its impact on the performance of the wall assembly;
• Determine whether the insulation that was not specified but was installed by a subcontractor, would be problematic in the performance of the wall.

Insulation and Flashing at Windows

• Determine whether the seams at polyisocyanurate insulation boards should be taped or not;
• Determine whether aluminum flashing under windows at punched-opening windows could be installed after the window frames were installed.

Anti-Graffiti Coating

• Determine whether an anti-graffiti coating could be applied to the brick veneer without negative impact on the performance of the wall.

Solutions / Deliverables :

• Researched alternative insulation products to meet thermal and flame spread criteria: Rimkus found an alternative product.
• Performed building code research to determine the requirements for insulation at metal panels: Rimkus concurred with the architect-of-record that mineral fiber insulation was required.
• Transient hygrothermal modeling was performed to test the impacts of several WRB products: Rimkus concluded that either impermeable or semi-permeable WRB’s could be used without negative consequences.
• Transient hygrothermal modeling was performed to test the impacts of unfaced insulation vs. FSK-faced insulation in exposed conditions: Rimkus concluded that there were no hygrothermal requirements for a vapor-impermeable layer such as FSK at these conditions.
• Researched the permeability of the specified latex paint products: Rimkus hygrothermal modeling included the use of a semi-permeable paint such as the one specified, and concluded that it presented no negative impacts on the wall assembly’s performance.
• Transient hygrothermal modeling was performed to evaluate the impact of FSK faced insulation in the stud cavity: Rimkus concluded that his product would have negative consequences by trapping moisture in the wall. The design-builder required the subcontractor to remove the gypsum drywall finish and replace the insulation with an unfaced product.
• Evaluated the need for taping of seams of the polyisocyanurate insulation adjacent to the wall’s airspace behind the brick: Rimkus concluded that, with a competent WRB behind the insulation, taping of seams was unnecessary.
• Evaluated a site mock-up of the wall assembly: Rimkus recommended that the specified aluminum insulation be installed prior to the installation of window frames, to ensure adequate quality control.
• Researched the permeability of the recommended anti-graffiti: Rimkus determined that there would be no negative consequences in the performance of the wall