Conceptual Reference Database for Building Envelope Research Prev

EIFS hygrothermal performance due to initial construction moisture as a function of air leakage, interior cavity insulation, and climate conditions

Salonvaara, M. H. and A. N. Karagiozis
Thermal Performance of the Exterior Envelopes of Buildings VII , December, Florida

Salonvaara, M. H. and A. N. Karagiozis, (1998), "EIFS hygrothermal performance due to initial construction moisture as a function of air leakage, interior cavity insulation, and climate conditions", Thermal Performance of the Exterior Envelopes of Buildings VII , December, Florida.
The drying capability of an EIFS wall system with initial construction moisture critically depends on the climatic conditions in which it is placed. The drying rate mechanisms with which walls redistribute and transport moisture away from the envelope may affect the service life of the wall system. Potential moisture-induced damage becomes important when the wall is not properly designed with adequate drying capacity. This paper investigates the drying performance of a particular EIFS (exterior insulation and finish system) clad wall. A state-of- the-art two-dimensional hygrothermal model, developed by the authors, was employed to determine the hourly spatial temperatures, moisture content, and air velocity distributions within wall systems as a function of real climatic conditions. In the parametric investigation, the performance of a particular EIFS clad wall as a function of two stud cavity insulation materials was studied. Two cavity insulation materials were investigated: fiberglass and cellulose insulation. Two climatic conditions were chosen in the moisture analysis, representing cold and mild climates; these were Chicago, Illinois, and Wilmington, North Carolina, respectively. The effect of wall drying and wetting in the presence of a particular airflow path (cracks) was investigated for all cases. The air leakage path was assumed to be present due to an electrical outlet close at the interior, an opening present between oriented strand panels, and a conduit in the stucco layer. Initial OSB moisture content was assumed to be very high. The influences of wind-driven rain, solar radiation, and air movement were included in the simulation analysis on an hourly basis. Results showed that air leakage through a particular EIFS clad wall in Wilmington produced a net drying effect for a wall system with an initially wet OSB layer, while air leakage developed a net seasonal moisture accumulation in Chicago. The effect of stud cavity insulation was found to be critical, as the storage capacity for moisture increased in the cellulose case, compared to the fiberglass insulation case. The distinct effect is present when comparing the two insulation systems. The cellulose insulation case retained higher amounts of moisture. Solar-driven moisture was also more critical in the cellulose insulation case than in the fiberglass case. The thermal and moisture results were then linked to a state-of-the-art mold growth model to assess the risk of moisture-induced damage. Results were developed in the form of mold growth indexes. Results showed the probable mold growth index potential as a function of climatic conditions and as a function of cavity insulation. Higher risk of mold growth is present in the cellulose case than in the fiberglass insulation case. If there is a high mold growth index and the underlying material is maintained at high moisture content, there is a potential for developing decay (if the wood is already infected internally). Since boric acid is added in cellulose insulation as a treatment for fire, mold, and insect and rodent control, as wet blown cellulose comes in contact with other materials, some of the chemical will treat these surfaces. For the same wall system, Wilmington exhibited slightly worse conditions than Chicago for mold growth. The development of mold growth indexes permits one to perform a moisture engineering analysis and extend current moisture assessment analysis of building envelopes' long-term performance.

Related Resources:

Related Concepts

Author Information and Other Publications Notes
Salonvaara, M. H.
Karagiozis, A. N.
Achilles N. Karagiozis, Oak Ridge National Laboratory, Building Technology Center, Oak Ridge
  1. A North American research approach to moisture design by modeling
  2. Advanced hygrothermal modeling of building materials using MOISTURE-EXPERT 1.0
  3. Advanced hygrothermal models and design models
  4. An educational hygrothermal model: WUFI-ORNL/IBP
  5. Applied moisture engineering
  6. Barrier EIFS clad walls: Results from a moisture engineering study
  7. Boundary element analysis of uncoupled quasi-static hygrothermoelasticity for two-dimensional composite walls
  8. Building enclosure hygrothermal performance study phase I
  9. Drying capabilities of wood frame walls with wood siding
  10. Hygrothermal system-performance of a whole building
  11. Importance of moisture control in building performance
  12. Influence of material properties on the hygrothermal performance of a high-rise residential wall
  13. Integrated approaches for moisture analysis
  14. Integrated hygrothermal performance of building envelopes and systems
  15. Measurements and two-dimensional computer simulations of the hygrothermal performance of a wood frame wall
  16. Moisture transport in building envelopes using an approximate factorization solution method
  17. Position paper on material characterization and HAM model benchmarking
  18. Simulation of indoor temperature and humidity conditions including hygrothermal interactions with the building envelope
  19. Wind-driven rain distributions on two buildings
  20. WUFI-ORNL/IBP - A North American Hygrothermal Mode  

CRDBER, at CBS, BCEE, ENCS, Concordia,