mozz, funny that you can afford to pay for monthly installment for 800K house and not afford the 5% cash payment (which is 40K). How much loan are you planning to take and you know why much interest you will be paying a year, say for 500K loan?
800k for 2 storey 1600 sqft pre-war house is on the pricey side if the condition is bad. 2 storey means the land area is probably just over 1000+ sq feet. Old pre-war house, you will need a lot of money to renovate. First thing is the roofing and then the drainage and sewerage.
If you like to stay in landed or need it for business it is ok. Landed prices are more stable and not subject to wide swings. So the prices of landed would not have gone up as much (despite the current hot market). Similarly it would not have too much of a downside. And generally as long as you can pay your bank loan, the bank would not ask you to top up when the property market is down - you think the bank so free to do valuation of all the properties that they have?
But take not of the restriction of using CPF. CPF have a restriction on how much money that you can use to pay for the house - now is 126% of the valuation or purchase price. And that is including all the interest. Most people don't know or take note of this restriction and 20 years later find that they cannot afford to pay for the house as they have reach the CPF approved limit.
If you are thinking of investment and appreciation in value of your property then forget about landed. Get an apartment in the choice district - even old run-down apartment. In property, it is location location and location.