The homeowner an engineer, was acting as his own contractor. He tarped the roof to protect the house from rain during a remodeling project. Rainwater entered the home because the tarping failed (exceptional volume of rainwater). And water damaged the interior walls, floors, structure.
Allstate denied coverage based on this policy language:

We do not cover any loss which consists of, is caused by, or would not have occurred but for, one or more of the following excluded events, perils or conditions. Such loss is excluded regardless of:
a) the cause or source of the excluded event, peril or condition;
b) any other causes contributing concurrently or in any sequence with the excluded event, peril or condition to produce the loss; or
c) whether the excluded event, peril or condition involves isolated or widespread damage, arises from natural, man-made or other forces, or arises as a result of any combination of these forces

11. Planning, Construction or Maintenance, meaning faulty, inadequate or defective:
a) planning, zoning, development, surveying, siting;
b) design, specifications, workmanship, repair, construction, renovation, remodeling, grading, compaction;
c) materials used in repair, construction, renovation or remodeling; or
d) maintenance;