Assuming that the mold situation is actually a result of the faulty product, then the homeowner would likely have claims under either the products liability statute or the redhibitory defects (i.e. sale of defective product) statute, or both. You do not give the time frame between the purchase, discovery, and asking the question, so some or all of the claims may be prescribed (barred by statute of limitations). You should seek counsel as soon as possible.
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