Budgeting cost for corner terrace

[jaconian 0]

Hello all,

I am embarking on a rebuild project for my family's first landed home. This will be our first time moving to a landed and embarking on a rebuild project, so I wanted to get some inputs/advice from seasoned professionals here. 

Land is a corner terrace, land size of ~3500 sqft. Looking to build 3 to 3.5 storeys, 5 bedrooms (3-4 with ensuite toilets), no pool, with lift. Looking at a double volume living/dining area concept so I would imagine the 2nd floor to be around 50-70% of the floor area of the 1st floor. What is a reasonable ballpark range for such a rebuild project (all-in costs)? Would $2.5million be sufficient? I contacted an architect I shortlisted and was advised to budget between $2.7 to $3 million (which honestly surprised me).

In terms of process, I have shortlisted some architects whose designs resonate with us, but at the same time, I know a builder through a mutual friend. Not sure who I should approach first? Am also cautious about working with a builder whom I have a mutual friend with - whilst I can be more assured that I won't be taken for a ride by said builder, it also makes things tougher to manage if there are hiccups during the building process. Any advice on how I should approach this?

Thanks in advance.