Other than a homeowners insurance claim, which might be handled on a contingent fee, a legal action against a adjacent condo owner would typically involve a retainer and an hourly rate, the amount of which would ultimately depend on the details and value of the controversy. I.e. if you have $500,000.00 worth of claimed damages, and a complicated legal dispute, your fee would be infintitely more than if you had a $5,000.00 and the owner was not denying liability and had insurance coverage.
The general advice would be that it would not hurt you to sit down with a lawyer offline and discuss the specifics (value, amount of damage etc.) and see where to go from there. You can use the avvo lawyer search to find a lawyer that offers a free initial consultation in your area.
Best of luck
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