Specifically, banks can seal up houses in the following ways:

1. Apply to the court for a ruling: the bank can bring a lawsuit to the court and request to seal up the property. The court will hear the case and make a judgment according to relevant laws.

2. Execution procedure: If you fail to fulfill the repayment obligation, the bank can seal up the property through execution procedure. During the execution procedure, the court will send bailiffs to your residence, put a notice of seizure on the door and seize the property.

To sum up, if your credit card debt cannot be paid off, the bank has the right to seal up your house. Banks can seal up by applying for a court ruling or execution procedures.

Supplementary information:

1. Seizure refers to restricting the transfer and disposal of seized property under certain circumstances according to the judgment or ruling of the court.

2. If the repayment cannot be made on time, it is suggested to negotiate with the bank as soon as possible and make a repayment plan as soon as possible to avoid possible legal disputes.

Please note that the above information is for reference only. Please consult a professional organization or lawyer for specific suggestions.