What is process of getting mortgage increased to cover renovation of the house?
Imagine we want to buy a house for 800k and we want to invest 200k in renovation (new heating system, kitchen, bathroom, floors). We have 200k of own cash, but we will need 20%*800k=160k for own contribution, which leaves us with only 40k for renovation. If we wanted to increase our mortgage to cover renovation how the process looks like? Before making the offer to the seller we wanted to make sure that bank will agree to give us more money for renovation. Otherwise we will end up with 40k for it which will be not sufficient.

Don't renovate, problem solved!

Tom

We had to put 20% deposit down for the purchase (but put a bit more down) and a further 33% of the renovation costs. We discussed this with the bank before making the offer.

Well, just because the selling price is 800k, it does not mean the bank will finance full 800k. They will do their assessment of the property value and finance that. Potential difference to the selling price of 800k you will need to finance on your own.

For renovation - inform the bank of the renovation you want to do with estimated cost. They will re-assess the value of the property and let you know what they can finance. Note if you invest 200k for renovation, it does not mean that the value of the property goes up by 200k. You will need to commit to the timeline for the renovation and at the end of the period, you will need to provide the invoices, photos, proofs of renovation work being actually done.