The built-in moisture in spray-applied cellulose fiber insulation (CFI) can significantly affect the hygrothermal performance of residential wood frame walls. In this application, CFI is installed in wet or damp form with water or adhesives used as bonding agents. Interior finishes are often installed without adequate drying time. In cold weather, particularly in north-facing walls, drying times may be much longer than anticipated.
Hygrothermal response of wood-framed walls after installation of spray-applied CFI was investigated using a combined numerical and experimental approach. A test hut study was undertaken in the mixed-humid climate of northern Georgia, and hygrothermal modeling was also carried out. The test results show that walls with spray-applied CFI dry out longer than anticipated. The accuracy of the predicted results was found to depend on inclusion of infrared radiation effects in the simulation. Additional simulations were performed for installations completed at different times of the year in the cold Detroit, Michigan, climate and in the hot San Antonio, Texas, climate. The results indicate that drying rates are dependent on time of year when the sprayapplied CFI is installed, particularly in colder climates. In cold weather, and in north-facing walls, the drying rates can extend for months. When spray-applied CFI is installed in January, moisture conditions near the sheathing can remain at high levels well into the spring, although moisture conditions closer to the interior decrease more rapidly. Moisture content measurement of the insulation during the drying period from the building interior using moisture meters may not detect the elevated moisture conditions that exist near the exterior sheathing. With vapor tight exterior sheathing, the walls are not capable of drying inward unless the indoor partial pressure of water vapor is below that in the insulation.
Citation: Thermal Performance, International Conference, 2010
Product Details
- Published:
- 2010
- Number of Pages:
- 14
- File Size:
- 1 file , 5.3 MB
- Product Code(s):
- D-BUILDINGSXI-144
