is used to estimate accrued depreciation for a single component or an entire structure and provides some improvement in accuracy over the straight line method as it allows a separate calculation for curable physical items and curable functional obsolescence.

In this method, the curable physical depreciation and the curable functional obsolescence is calculated first and then deducted from the cost new of the improvements before the applying the percentage of depreciation to the cost of the remaining incurable improvements. This method assumes that there is generally a uniform decline in value with time.