If the builder is responsible under the contract for rectification, that will be factored into the cost of the contract, i.e. the OC will effectively be paying for it.
In some circumstances the OC and owners may agree for each to meet their own rectification costs, e.g. a friend of mine lives in a block where each owner was responsible for the cost of rectification to their apartments subsequent to installation of fire sprinklers. They figured that as the owners were the OC, they might as well each meet the costs themselves and do some other work if they wanted to at the same time.
A while ago in our building an owner sought permission to renovate their kitchen and bathroom, which included new tiles around the windows, while knowing that we would be replacing the windows. We granted permission subject to them agreeing that they would bear the cost of reinstating those tiles, because they had the option of putting the tiles up later.