Of course, you cannot offer any other guarantees than your house, which is already mortgaged by the first loan.
What is the most interesting solution for you: establishing a second mortgage or refinancing your first loan and adding an additional amount of €50,000 guaranteed by the first mortgage.
State of this recurring question.
The establishment of a mortgage incurs costs
When you buy a property, you will often be asked to agree to the establishment of a mortgage. Often, this guarantee will be a sine qua non condition for obtaining your loan.
The establishment of a mortgage incurs significant costs that will be added to the purchase price of your house.
Mortgage refinancing is the most advantageous solution
If during the life of your mortgage loan, you need to borrow new sums of money to, for example, carry out work on your house, it will always be more advantageous to refinance your mortgage loan, increase it by the desired new amounts, and maintain the establishment of the mortgage rather than agreeing to the establishment of a new mortgage that would incur new costs.
In such a situation, consult your usual broker who will analyze your situation and advise you best.