Moving has costs that do not appear in the asking price. On a R9 million purchase, transfer duty alone runs to several hundred thousand rand; add agent commission on the sale of your current house, bond registration, conveyancing and the move itself, and the friction is commonly 8% to 11% of the value of the transaction.
New floor area, by comparison, costs between R18 000 and R30 000 per square metre finished to a high standard in this part of Johannesburg. A 96 m² double-storey addition therefore sits in the same range as the transaction costs of moving up one bracket — with the difference that you keep the stand, the trees and the school run.
Extending is the wrong answer in three situations: when the stand cannot take the coverage, when the existing services are so poor that the whole house has to be rebuilt behind the extension anyway, and when what you actually want is a different suburb.
We will tell you when we think you should move. It has happened four times in fifteen years, and each time it was the right call.