If you are worried about the room addition cost of the space you are adding onto your home, then take a breath and do some more research. It may be that the room addition cost is high because you are being too ambitious. I know you might not want to hear this, but there may be a distinct chance that you are going to need to edit your plan a little. IN like manner, it may be that the contractor you have hired, or are thinking about hiring is charging way too much for the job. Be sure to shop around aggressively before hiring someone to do you room addition work.