Can't help the OP but would agree that a flat roof does affect price. No idea by how much though.
THIS property with a flat roof two streets away from me has been on the market for about two months. I don't think that they will get their asking price as other properties in the same area are going for R1.4m - R1.7m.
I picked up my property for R950k just over 3 years ago and can possibly get close to R1.6m in current market conditions. I would never consider a flat roof. It just doesn't appeal to me.
Mine below. Have about 2.3m height and 6m width in the roof. Will eventually be putting in some dormer windows in the front and back to make use of the space in the attic.
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