won a $73k USAA foundation claim that was initially denied under "earth movement" - the concurrent causation argument that finally cracked it open

posting this because i could not find a clear writeup when i was in the middle of it and "earth movement" denials seem to trip up almost every foundation claim i read about here. tldr at the bottom for people skimming.

house is a 1998 ranch in north texas, clay soil, USAA HO-3 policy held since 2014. noticed a stair step crack in the south wall in october, then a second one in the garage along with a sticking door. got a structural engineer (not USAAs, an independent one i hired for $850) who came out and put it bluntly - the south side had dropped about 1.25 inches and the foundation needed 18 push piers plus interior slab repair. estimate from the engineer's preferred foundation contractor: $73,400.

filed the claim in november. USAA sent their own inspector who agreed there was damage but denied citing the "earth movement" exclusion on the policy. their letter quoted the standard ISO language - loss caused by earthquake, landslide, subsidence, soil expansion or contraction is excluded. textbook denial. i was ready to write it off until my engineer mentioned offhand that the moisture readings around the south footing were "strange for october" and asked if i had any plumbing issues.

turned out i had a slow drain line leak under the slab on that exact side of the house. the plumber found it after we ran a static test ($425). the leak had been there long enough to overhydrate the clay on one side and not the other, which is exactly the kind of differential soil movement that causes a footing to drop. the engineer wrote a supplemental report stating with reasonable engineering certainty that the proximate cause of the foundation damage was the plumbing leak, with soil movement as a downstream mechanism rather than an independent cause.

that distinction is the whole ballgame. texas follows the "concurrent causation" doctrine which says when a covered peril (sudden plumbing leak, which is covered) and an excluded peril (earth movement, which is excluded) combine to cause a single loss, the insured can recover for the portion attributable to the covered peril. some states do this differently (california uses "efficient proximate cause" which is even more favorable to insureds in some scenarios). but in texas the standard is concurrent causation with the burden on the insured to segregate damages.

submitted the supplemental engineer report, plumber leak documentation, and a written demand citing the concurrent causation doctrine and the specific covered peril language in the policy form (water damage from accidental discharge of plumbing). USAA reopened the file and assigned a senior adjuster. they sent another inspector who confirmed the leak path matched the damage pattern. they paid the full $73,400 minus my $2,500 deductible.

tldr / lessons: if you get an earth movement denial on a foundation claim, do not stop at the inspector. (1) get an independent structural engineer who is willing to write about proximate cause not just damage. (2) check for plumbing leaks under the slab - they are stunningly common and you need a static test, not just a visual. (3) if there is any water issue at all, argue the covered peril (plumbing leak) is the proximate cause and the soil movement is a downstream mechanism. (4) know whether your state uses concurrent causation, efficient proximate cause, or strict anti-concurrent causation language because that determines whether the argument even works. (5) the policy language matters - if your policy has explicit anti-concurrent causation language (some carriers added it specifically to block this argument) you will have a much harder fight. mine did not, USAA HO-3 in texas in 2014 was still using the older form.