This is too late for you, but maybe of value for others to consider: Having the builder include it would have been less disruptive, almost certainly much cheaper, and probably better itegrated into the structure. Sure the cost then adds to the mortgage, but thats doesn't mean you are stuck with financing it for the life of the mortgage. Just pay that amount anytime you want as an extra payment on your mortgage, and its done, you're no longer financing it. Doesn't cost any more than paying someone to do it now. Most, (not all) home loans allow such overpayments w/o penalty.