Wind Damage. Evidence of wind damage include shingle failures, partial roof failure, broken windows, and garage doors blown in or out. This type of damage may be accompanied by failure of one or two walls and partial failure of the roof.
Roof-to-wall connections. Record the size and number of nails connecting top plate to roof rafter or truss. Document evidence of whole body removal of a roof (i.e. as a complete component; the building’s content remain intact the wall still standing).
Anchorage of structural walls. Record the diameter of anchor bolts and their spacing apart, size of the washers holding the wall plate to foundation, and dimensions of the wall plate.
Connection to supports. Document the size and number of nails connecting stud to wall plate, and top plate to stud; dimensions of the studs, distance/spacing, number of nails, and size of nails; and how the corner of the buildings performed and their structural details- how is the stud pack fastened together?
Debris. Document evidence of wind direction. Where did the debris from a house go? What direction were they thrown? For what distance?
Personal Interviews. What can the owners tell us about the tornado impacts? What failed first? What failed next? Was the debris blow into the building or were items pulled out of it? Where were the people in the house? How much debris?
Details sketches. Labeled sketches are immensely helpful in understanding what photos purport to show. Do not expect photos alone will be sufficient for important details of failures or that you can memorize and draw/sketch a detail later; take the time in the field to draw out what you see, and to measure and mark the dimensions on it, right there.
For more information consult FEMA Load Path document that illustrates the concept of load paths and highlight important connections in a wind uplift load path.
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