I
Given the quick response, the methodology employed to evaluate the performance of manufactured housing support systems needed to be straight-forward and simple. A checklist form was quickly prepared to determine the number of homes within a mobilehome park, the number down, and, the types of support systems used on the homes that were down. Twenty-seven mobilehome parks under both HCD and local jurisdictions were evaluated under this method. Five-hundred ninety-two (592) of the two- thousand thirty-four (2,434) homes in these parks were down (24%), and the types of support systems of those homes down were carefully recorded.
Evaluation of the data collected indicated the need for additional information. It was of little value to our subsequent analysis to know what types of support systems were used on homes downed by the earthquake, but not to know what types of systems supported the homes that did not go down.
II
Inspection staff returned to 12 of the 27 mobilehome parks initially surveyed to determine the type of support systems employed on homes that did not go down. Time did not permit a re-survey of all 27 parks so those parks with the greatest number of homes down were selected. In these 12 parks containing 1,239 homes, 479 homes were down (39%). Enforcement jurisdiction in these 12 parks was also a combination of HCD and local jurisdictions.
During this re-survey data was accumulated with respect to one type of support system, in one park, that was inconsistent with the findings in other parks. This support system, concrete block, demonstrated a much higher failure rate in this particular park than in any other park surveyed.
III
Inspection staff returned to that one park, where a higher than average failure of concrete block support systems was encountered, to determine the possible reasons for the lower performance.
