Commentary on FEMA P-807 for Retrofit of Wood-Frame Soft-Story Buildings

The FEMA P-807 guideline titled Seismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings with Weak First Stories is a new approach for building retrofit. It goes beyond current building codes and standards by quantifying performance in probabilistic terms. The authors performed an independent review of P-807, and the resulting commentary herein covers five topics: (1) building lateral force-drift (backbone) curves, (2) building interstory drift limits, (3) lateral strength requirements, (4) collapse safety margins, and (5) site class effects. It was concluded that P-807 may be an efficient way for relative ranking and selection of retrofit designs—but it has questionable accuracy for predicting actual building performance (i.e., the probability that a particular seismic intensity will result in a meaningful state of damage for a specific building).