HSN/SAC

Check Heading 9954 in attached file and select your SAC appropriately.

Btw GST 12% is applicable only for " Construction of a complex, building, civil structure or a part thereof, intended for sale to a buyer, wholly or partly.
[The value of land is included in the amount charged from the service recipient] "

i.e. 12%  With Full ITC  but no refund of overflow of ITC

9954 SAC code for civil work which includes Construction of a complex, building, civil structure or a part thereof, intended for sale to a buyer, wholly or partly (the value of land is deemed to be one-third of the total amount charged for such supplies) with no ITC.

For your more doubt and issues related to GST, you can visit GSTForumindia.in and ask your question freely.