Cost data are generated by HomeTech Information Systems, which updates its database of construction costs quarterly, using construction commodity data, as well as labor cost information from a nationwide network of remodeling contractors. The company prepares a detailed construction estimate for each project, then adjusts this baseline cost for each city to account for regional pricing variations. Construction cost figures include labor, material, and subtrade expenses, plus industry-standard overhead and profit. However, project costs are based on estimates for hypothetical projects, with no reliable way to accommodate short-term fluctuations in supply and demand.
Resale value data for each project are aggregated from estimates provided by members of the National Association of Realtors. In cooperation with Realtor magazine, e-mail surveys containing project descriptions and three-dimensional illustrations, plus construction costs and median home price data for each city were sent to some 150,000 appraisers, sales agents, and brokers. More than 4,000 survey respondents used this information to estimate the value that each remodeling project would add to the house at resale in the current market. Respondents were instructed not to make judgments about the motivation of the homeowner in either the decision to undertake the remodeling project or to sell the house. The survey was in the field for approximately eight weeks in July and August of 2009.