I have always found private outside space to be of great value to the Chicago buyers. We really appreciate our time out of doors since it can be so limited, and I have found it to be a good investment. I agree that you rarely get 100% of investment on return, but it can definitely improve the saleability of your home and also increase the value. I am working with buyers now that demand a roof deck. Since our lots are small comparatively, any increase in usable living space (even outdoors) is a plus!!