We're not attorneys, so take this as general information, but our read is that a bank would have a hard time forcing its way back in after its own error. If the release means there is no longer a lien securing your home, and you place new financing after a clean title report and title insurance, there's no obvious mechanism for the original lender to reinsert itself into first position ahead of your new lender once that new loan records. Start by reading your deed of trust or mortgage carefully. Partial releases like this are uncommon, and the document controls what recourse the lender actually has. If the loan documents don't give the bank a clear remedy, unwinding things after a new lender has relied on clean title and issued a policy becomes highly unlikely. The stakes here (a low-rate loan, a build, competing lien positions) justify paying a real estate attorney to review your specific documents and your state's law before you move. Get the deed of trust reviewed, confirm clean title, and let a lawyer bless the plan before you draw new financing against the home.