I have a bedroom/sewing room. I think first with the measurements of your current room and do you have enough/satisfied and would do with same size or do you want larger. With most additions you have to get permits and that can involve engineers, etc. With a shed, there are various sizes you can build and that would also determine your budget. Would you be able to put an interior stairway in the garage to access your sewing room that may save even more money and not have to worry about potential falls/slippage. I would start with measurements of the space you're using now and go from there. One thing I definitely suggest is that you do not keep the falling from your husband. If I had a shed, it would have to be every bit the size I'm utilizing currently. Like I said measurements are key. Good luck!!