Pennsylvania State University

Principal Investigator, E.F.P. Burnett

TC 4.4, Building Materials and Building Envelope Performance

Currently very little information exists as design guidelines on weather barrier systems for combined thermal and moisture performance of wood frame wall systems. The criteria to determine whether wall cavity ventilation should be used or not, in different climatic areas, does not exist. Research is needed to define how to design such air cavity systems considering both thermal and moisture performances of the complete wall system. Many examples of moisture related problems exist, and many have been recently attributed to improper design of the cladding system. Performance data of critical wall elements such as sheathing membranes and air cavities should be provided in the Handbook of Fundamental to assist envelope designers.

The information generated from this project will also provide the new SPC 160P on Prevention of Moisture Damage with valuable data to assess moisture damage. Currently the Handbook of Fundamentals does not clearly indicate design considerations and practices. The results from this research project will provide guidelines and practices to be included in the 2005 ASHRAE Handbook of Fundamentals.

The objective of this research project is to generate experimental data on the performance of sheathing membranes and air cavity ventilation strategies on the total performance of wall systems and to develop guidelines on the combined performance of sheathing membranes and air cavity ventilation strategies as a function of climatic conditions using modeling. This will provide: a) Knowledge on the interactions of air cavity and weather barrier performance as a function of climatic conditions and as a function of cladding properties. b) Experimental data to provide valuable validation data for heat, air and moisture transport models which in turn are used to generate the performance of the cladding and weather barrier on the hygrothermal performance of wood frame wall systems as function of climatic conditions.

• design
• sheathing
• wood frame houses and walls, wood structure

1. A review of rain control and design strategies
2. Drainage, ventilation drying and enclosure performance
3. Driving rain and building facades
4. Field testing of filled-cavity wall systems
5. Moisture movement in building enclosure wall systems
6. Overview of hygrothermal (HAM) analysis methods
7. Rain control and screened wall systems
8. Simplified prediction of driving rain deposition
9. The Ontario wall drying project
10. Uncertainty analysis for vapor pressure measurement
11. Ventilation drying in enclosure wall systems
12. Vents, ventilation drying, and pressure moderation