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Avoiding Building Envelope Failures

Remediation Process Specifications

To help the Owner(s) with the decision-making, the following process can be used:

  1. Preparation for multi-family complexes: Select accessible, typical problem unit(s) to serve as test unit(s) for determining the feasibility and economic value of selected corrective measures.  Form a decision-making team comprised of the architect, the diagnostician, the builder, and a designated member of the Owner’s organization.  In single-unit buildings projects, the process will be the same, but the selection of test units will not be necessary.

  2. Phase I diagnostics and repairs: (See “Theoretical Considerations” in the Thermal VII paper for details about why the phase approach is required.)

    1. Collect all available data about the problem.  This includes frost, snow-melt, and ice formation pattern photos or a map or description of the locations where the problems occur.  Information about when, under what type of weather conditions, and where the problems occur is very important to understanding the problem.

    2. Review any available drawings and/or construction photos and make any non-destructive physical inspections of the building conditions.

    3. Perform non-destructive diagnostic procedures (natural and pressurized infrared thermography) on the test units to identify and locate the most significant causes of ice dams. The two major targets of this testing are air leakage (holes) and conductive heat loss (missing or inadequate insulation) areas that could warm the outer roof surface enough to melt the snow cover in below-freezing weather conditions.  Ventilation may also be an important issue once major heat losses are determined to be under control.

    4. Based on the project data collected and the results of the non-destructive testing, develop any small-scale access openings (destructive) in critical or typical areas for the inspection of specific construction details associated with air leakage, conductive heat losses, and ventilation issues that are resulting in warming of the outer roof surfaces.

    5. Report on the findings, providing a list of the likely causes of the problems, and propose corrective measures, including estimated costs for these repairs.

    6. The team then meets to review the evidence, prioritize the problem areas, and generate a phased plan of attack.  The evidence should be presented in a manner that clearly provides adequate information to assess the direct relationship between the problematic ice formations and the identified thermal envelope problems.

    7. Contract with a builder to make the Phase I repairs (designated as the highest priority) on the test unit(s).

  3. Phase II diagnostics and repairs

    • After the Phase I repairs, operate the test building(s) without preventive measures including snow shoveling or raking and the use of electric eave heaters.

    • Monitor the performance of the repairs by taking photos of the new frost, snow-melt, and ice formation patterns and map or describe the locations where and to what degree the problems still occur.

    • Perform a second series of non-destructive diagnostic test procedures to locate the remaining causes of the ice dams.

    • Report on the findings, providing a list of the likely causes of the problems, and propose corrective measures, including estimated costs for these repairs.

    • The team then meets to review the evidence, prioritize the remaining problem areas, and generate the next plan of attack for the areas that require additional repairs.

    • Contract with a builder to make the Phase II repairs on the test unit(s).

  4. Monitor the performance of the repairs by taking photos of the new frost, snow-melt, and ice formation patterns. Map or describe the locations where and to what degree the problems still occur, if any remain.

  5. Report the results to the Team.

  6. Identify the components of the process that will be required to successfully repair the balance of the units.

  7. Plan the long-term work for the rest of the units.

  8. This process may also include an assessment of the resulting change in building performance.

    • Collect all data outlined above during the winter season if the work will extend into the warmer months.

    • Determine and prioritize which units will require repairs. Identify where the problem areas are in these units.

    • Perform non-destructive testing during the winter season if the work will extend into the warmer months.

 Theoretical Considerations (excerpt from the Thermal VII paper)

The process outlined above requires two phases of testing and remediation work.  In the first series of testing procedures (Phase I), only major conductive and air-leakage loss areas could be identified because the larger losses overwhelmed or “concealed” smaller ones.  In the case of air leakage, large openings reduced the pressure differential across the barrier, and the smaller, more restricted openings had little or no flow.  In conductive loss areas, large uninsulated sections of wall or roof concealed or reduced the apparent importance of relatively poor R-value areas.  The initial (Phase I) testing gave an overall sense of the problem and determined that the primary causes of the ice formation were not failures in the insulation or ventilation systems in the cathedral roofs.  It identified the areas requiring improvements and aided in prioritizing them.  This procedure also provided a benchmark for comparative quality assurance procedures for the project.

After the Phase I improvements had been completed, the infrared and melt patterns in Phase II testing provided much more concise information about smaller, concentrated heat-loss sites.  The pressure differential across the remaining small openings increased, allowing them to be easily detected.  The second round of testing also gave the contractor making the improvements feedback about the initial round of work.  Usually, this was done prior to closing access areas and replacing finishes. By incorporating a review step and fine-tuning into the planning, there was less pressure to address potentially low-payback repairs in the first phase, resulting in cost savings on several occasions.  This also allowed everyone involved to assess the impact of the initial work, and to develop and try alternative techniques to overcome problems encountered in the first Phase.  Creating a cooperative effort where everyone worked together to accomplish practical goals resulted in a much lower probability of failure.  For all of these reasons, it was clearly important that at least two series of tests be performed