Loans originated or purchased by the Administration shall meet the following terms and conditions: The Administration shall establish or determine an interest rate or rates and other charges and fees, if any, for loans that, together with other moneys made available for those purposes, are sufficient to meet the interest and other costs payable by the Administration for its revenue bonds or other obligations financing the loans, administrative expenses of the program, and possible losses due to loan defaults in the program. The interest rate or rates on loans may not exceed the maximum permitted by §103 or 103A of the Code as applicable. The Administration shall set maximum and minimum terms for loans taking into account the terms of the revenue bonds or other obligations issued to fund loans. Loans may be made in any amounts that are necessary to finance eligible improvements, but may not exceed the lesser of the limits set by any loan insurance program, if applicable, or: $15,000 for each property containing from one to four units, one unit of which is occupied by the owner; or $30,000 for the first dwelling unit and $20,000 for each additional dwelling unit for each property containing: One to four units, all units of which are occupied by families other than the owner, or Five or more units. Borrowers shall repay the loan in substantially equal monthly payments of interest and principal in order that the loan is fully amortized over its term. Borrowers shall pay any servicing fees, loan insurance premiums, or late charges that the Administration or the loan insurer may require and that are permitted by State law. Securing of Loans. Loans shall be secured as required by the Administration and any loan insurer. Property improvement loans shall be secured by a mortgage. Energy loans in an original principal amount greater than $5,000 shall be secured by a mortgage. The Administration may require that energy loans in an original principal amount of $5,000 or less be secured by a mortgage. Borrowers shall maintain fire and extended insurance coverage in an amount not less than the outstanding principal amount of the loan and any other prior debt secured by the property. The Administration may prohibit assumptions of loans. Borrowers may prepay a loan to the extent permitted by the trust indenture. Borrowers may not refinance existing debt or work in place before approval of the loan. The loan shall comply with any restrictions or requirements of the trust indenture. Borrowers shall execute a note, a mortgage (if required), a borrower's affidavit, and any other documents that the Administration requires in order to evidence or secure the loan or to comply with the Code, the Act, these regulations, or the policies of the Department, Administration, or Program.