House price depreciation rates and level of maintenance

My results show that the depreciation rates are significantly different for a maintained property and for a property that is not maintained. The price difference between a 40-year-old property (built in 1960) and maintained both indoors and outdoors and a property of the same age that is not maintained is about 13% (−10% compared to −23% in total age effect). The absence of outdoor maintenance has more impact on price depreciation rates.