Abi, about half of the cost is the land cost. Contractors are now negotiating between 25% and 45% on average. The prices of parcels suitable for zoning have literally skyrocketed, only difference is that you pay for it in advance.The contractor himslef explains that construction of buildings with isolators increases the construction cost by a mere 10-15%.
In the other half of the cost, rough construction is about 25% of the total construction cost. Fine works, equipment and all other construction-related expenditures are the remaining 75%. In other words, making the earthquake isolator compulsory increases the cost of rough construction by about two times, but its share in the total cost is probably less than 10%. If the government lowers the mortgage rates for buildings with isolators a little bit and, for example, if some of this additional cost is deducted from the tax base of the contractor, we can settle this very quickly.
In my opinion, the most important issue is that raft foundation and bored pile technique must be mandatory without being determined according to the ground survey. The other issue is that especially the houses with commercial floors are inspected every year by building inspection companies for non-compliance with the project, column cutting, carrier system removal, etc.