Wall Height Shrinkage Calculator

HD = the height of the wall section (involved height); for horizontal joint design, HD = HL
MCD = the design moisture content
MCS = the service moisture content
MCFSP moisture content at fiber saturation point
S = the shrinkage coefficient (%) in radial (SR) or tangential (ST) direction

* Formula: shrinkage =(HD*(MCD-MCS))/((MCFSP*100/S - MCFSP)+MCD)

302.2.2.3 Design moisture content (MCD). The target moisture content shall be used to determine the design moisture content (MCD) for the purpose of calculating settling due to dimensional change in accordance with the following: 1. Kiln drying used to establish the design moisture content (MCD) shall be in accordance with approved methods. When the average moisture content in a kiln charge achieves the target level or lower, the target average moisture content shall be accepted as the design moisture content. Certification of records, procedures, and actual measurements shall be provided by third-party inspection.

302.2.2.4 Service Moisture Content. The service moisture content (MCS) shall be determined by one of the following methods:
1. Presumed to be 12%
2. Selected by geographic climate zone using Figure 302.2.2.4 and Table 302.2(1).
3. Calculated in accordance with ASTM D 4933.

Table 304. -
Moisture Content of Selected Wood Species at Fiber Saturation
Wood Species / Groups Average moisture present at fiber saturation (MCFS)
Yellow Poplar 31
Engelmann Spruce, Red Oak30
Alaska Cedar, Douglas Fir-Larch, Western Hemlock28
Southern Pine26
Western Red Cedar18
Sitka Spruce28
All other species30