My and my friend's family want to cooperate in buying one house and convert/rebuild it to 2 units(semidetached). Is it be possible to get one cooperative mortgage or two mortgages for one property from bank?
You'll only get one mortgage, secured on one property, and naming all owners as mortgagors.
You can make a preliminary approach to some banks and see if they would be inclined to consider your project. They would want some sort of plan/projection and the feasibility of what you are proposing together with evidence that the proposed mortgagors can afford the repayments.
Can I suggest that you might take specific advice from a solicitor based on your specific circumstances?
You'd need to start with the actual title, review what planning issues might arise, review if there are restrictions in the title preventing a sub division, work out a scheme of obligations and responsibilities for any shared services/supports/structures etc.,etc.
Will the initial cost, plus the division costs be worthwhile financially. As in will the two new units be worth more than those costs. Otherwise getting two separate mortgages later might be a problem. Is planning easy. Will it be possible to have two driveways etc.
Sewrage, electricity and water will need to be separated.