13 CFR §123.106

1. (a)If your home (primary residence) is totally destroyed or substantially damaged, and you do not have credit elsewhere, SBA may allow you to borrow money to refinance recorded liens or encumbrances on your home. Your home is totally destroyed or substantially damaged if it has suffered uninsured or otherwise uncompensated damage which, at the time of the disaster, is either:
   1. (1)40 percent or more of the home's market value or replacement cost at the time of the disaster, including land value, whichever is less; or
   2. (2)50 percent or more of its market value or replacement cost at the time of the disaster, not including land value, whichever is less.
2. (b)Your home disaster loan for refinancing existing liens or encumbrances cannot exceed an amount equal to the lesser of $500,000, or the physical damage to your primary residence. Any refinancing amount will be reduced to the extent such lien or encumbrance is satisfied by insurance or otherwise.