Appraisers in 2004 have access to far more property data than was available ten years ago. Much of the new data is available by way of the Internet.

As in the past, useful information for a given property includes a city Assessor's field cards, assessors' plat maps, and zoning maps and bylaws. However, appraisers now frequently can access data of this kind on the Internet and no longer need to search city halls for damaged or out of date hard copy . Web-based sources include these:

- online zoning data from cities and towns
- FEMA flood maps available at no-cost sites
- deeds and other legal records, from county Registries of Deeds

Aerial views and GIS (Geographical Information System) displays have come into common use from several sources:

- high-resolution images at no cost, available from the Boston Redevelopment Authority Web site
- state web sites, which include aerials, street maps, and land use data
- MassGis in Massachusetts for wetlands maps, hazardous waste spill locations, protected open space maps, and street and highway maps

The data from these sites can be downloaded for use with an appraiser's own GIS application such as ArcGIS, MapInfo, or Maptitude.

Census data is available at and at industry sites like Private demographic companies like Claritas offer updates of Census data and provide data that are useful to analyze spending patterns in a defined community. The federal government reports unemployment statistics online monthly for the nation, each state, and each metropolitan area.

Commercial real estate services provide the data that form much of the basis of appraisers' analyses:

- the Spaulding & Slye Report (Greater Boston rent and vacancy data)
- the National Real Estate Index, for metro area price and rent trends
- REIS, with online apartment, retail, office, and industrial market data
- NAI Hunneman Commercial, CB Richard Ellis, and other commercial houses
- publications from the restaurant, gas station, self-storage, and other industries

Sales and lease data can be obtained online. The most popular source for commercial property sales data nationally is CoStar Comps. This is a service that provides complete sales data and that can be accessed by subscription or on an "as needed" basis. REIS has a similar service. In Greater Boston, Banker & Tradesman's online service provides a broader range of data, reporting all sales transactions above a threshold consideration. Residential analysts depend heavily on online MLS data. For commercial property lease data, appraisers use Loopnet, CoStar, and a new service, The quality of the comparable sales data available online is such that field research is still required for mistake-free appraisal.

William T. Whiting, Jr.

  • 24 Thorndike Street
    Cambridge, MA 02141

About Us

Eric Reenstierna Associates LLC is a real estate appraisal firm taking on valuation and consultation assignments in Greater Boston, Massachusetts and New England. Eric Reenstierna, MAI, is the office's principal and is a commercial real estate appraiser.


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(617) 577-0096

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