SIP plans

[peachpeach 2]

hi, is SIP and DIP plan a necessity or good to have before OTP? the owner does not have any floor plan. we do not intend to do tear down/major aa/add another storey. we are probably looking to push out/extend the front part to add a balcony and simple renovation. 

[snoozee 98]

No harm buying as its just a few tens of dollars.
 

With a DIP, at least you know whether your house is affected by any drainage reserves which you may need to surrender to the state if necessary in future. 
the SIP will let you know where the sewer line is and whether it will affect your extension plans if you have any