Percentage of GST on Construction Service by the Builder charged to Land Owner on Apartments

Dear Sir, what is the value of flat and the percentage of GST on Construction Service to be paid on the flats of share of Land Owners in Joint Development Agreement ? 

I read the value of Land owners flat is 2/3rd value of first sold flat from date of signing JDA as the GST is not on value of land. 

Also I read it is 1% or 5% GST depending on affordable or nonaffordable flats. 

Since details and share of flats already allotted to Builder and Land Owner in registered JDA in advance, since no conveyance deed is required to register again and since completion certificate is already issued is there any GST on Construction Service is applicable.