 For purposes of discussion, we will assume that everybody expects the construction of the house to take about six months.There are a couple of choices of how to proceed.Under the Financial Institutions Reform, Recovery, and Enforcement Act of 1989, the valuation of a property with proposed improvements is required to be valued in its 

Often the purpose of a particular appraisal may be not the determination of the value of a property, but rather the determination of the contributory value of a particular component or portion of the property or the effect on value of a particular condition affecting the property or proposed to be imposed on the property.