It only makes sense to apply for extra money if you do not have enough savings to pay for the renovations. Even if you apply for extra money, you will probably not get the full amount, because the mortgage provider will only borrow you the difference between the Market Value before renovation and the Market Value after renovation. In most situations the valuator will only add half of the renovation costs to the Market Value. So if the total renovation costs will be 25.000 euro, you might have to pay half of them from your savings and the other half can be borrowed through the mortgage.