Conventional wisdom is that the number of claims in a given period is
more important than the size of a given claim. I know people who have
filed claims for $5,000 to $10,000 with no adverse effect on their
premiums.
ISTM rather foolish to withhold a $20K claim on a $500 deductible
policy. You might be giving your insurer a large windfall (not though
not necessarily $19,500).
BTW, $500 is a fairly low deductible for that value of house. I would
explore an increase (though your mortgage may mandate a floor).