Architectural Investigation - How to Learn About Your Old House

Tips to Understanding Before Swinging the Hammer

Uncover the mysteries of your older home with a process known as architectural investigation. You can hire an expert to create a professional study, or you can do it yourself. The US Department of the Interior helps us understand the tasks involved in Understanding Old Buildings: The Process of Architectural Investigation (Preservation Brief 35) written by architectural historian Travis C. McDonald, Jr. Here is a summary of his guidance and expertise with links to the complete document online.

Note: Quotes are from Preservation Brief 35 (September 1994). Photos in this summary article are not the same as in the Preservation Brief.

What Is Architectural Investigation? Can I Do It?

Beautiful springtime flowering tree in front of a 19th century house in Bonn, Germany
Cherry Blossoms in the Historic District. Photo by Andreas Rentz / Getty Images News / Getty Images

When you buy an older house, a history comes with it. You are not the only occupant who will have stared at those walls, fixed the roof, and thought about how to expand your living space. Older homes have usually evolved, inside and out, and figuring out how and when those changes happened helps us determine what needs to be done next.

How do you do it?  "Architectural investigation can range from a simple one hour walk-through," explains architectural historian Travis McDonald,  "to a month long or even multi-year project-and varies from looking at surfaces to professional sub-surface examination and laboratory work."

An architectural investigation may take place for different reasons, including a curiosity about history, the accurate preservation of a historic building, or the emergency repairs needed to keep a building standing. It's good to know what your goal is before you begin. McDonald says:

"Whether investigation will be undertaken by professionals—architects, conservators, historians—or by interested homeowners, the process is essentially comprised of a preliminary four-step procedure: historical research, documentation, inventory, and stabilization."

"The essential skill needed for any level of investigation," claims McDonald, "is the ability to observe closely and to analyze. These qualities are ideally combined with a hands-on familiarity of historic buildings—and an open mind!"

The architectural investigator is curious about history and as patient and methodical as an archaeologist. The investigator will understand the regional building techniques and common architectural styles of the area. This knowledge often is passed down from neighbor to neighbor, but it also can be learned from schools. The Secretary of the Interior provides guidelines for minimum education and experience required if you're searching for a qualified professional.

Gathering Architectural Evidence

Black and white photo of a Victorian parlor, with fireplace and lead glass windows, around 1900
Old Photos Are Invaluable Research Tools. Photo by Jonathan Kirn / Corbis Historical / Getty Images (cropped)

"Most structures over fifty years old have been altered, even if only by natural forces," explains Travis C. McDonald, Jr. Occupants leave their marks on a property as much as the weather does. A goal of any investigation is to estimate a starting date and trace the changes that have occurred and when they probably happened. People make changes to buildings for any number of reasons—additional space, technological upgrades like indoor plumbing, and sometimes people make changes just because they can! Careful observation from different sources provide clues. A common starting point beyond examining the structure itself is the old, family photograph. Inside and outside, old photos often provide visual details of the past and how the house used to look.

"Buildings acquire a 'historic character' as changes are made over time," says McDonald. A sidebar to McDonald's print-version text is an examination of a specific farmhouse in Delaware. Academic historians Bernard L. Herman and Gabrielle M. Lanier put together Showing the Evolution of an 18th Century Farmhouse to supplement McDonald's Preservation Brief 35.

Historic Building Materials and Features

Poorly constructed brick wall detail
Poorly constructed brick wall detail. Photo by Scott Peterson/Getty Images News Collection/Getty Images (cropped)

The most basic questions to answer are (1) what is the structure made of and (2) how is it made? In addition to ancient materials like adobe, McDonald points us to analyze these building materials and features:

  • Masonry: Both brick- and mortar-making have gone through many improvements throughout the years. Careful examination of interior and exterior brickwork can reveal approximate time periods.
  • Wood: Don't forget to examine nails and other fasteners when investigating how wood was cut and the types of wood used.
  • Roofs: Availability of different roofing materials has expanded over the years. Past layers may still be present on older homes.
  • Floors: Often newer flooring has been installed over older. For example, when preservationists pulled up flooring in the studio of artist Jackson Pollack, they found paint splatters from Pollack's early works. Are there patterns to observe in your home?
  • Walls: Follow the trim, and make careful observations about inconsistencies. Dare to find out what is behind walls.
  • Attics & Basements: Besides the stored castaways of past projects, attics and basements are often the places where structural elements can be easily observed.
  • Systems Technology: In colder climates, house heating systems dramatically changed throughout the life of an older home. Plumbing, waste disposal, and electricity are systems that will leave a mark as to how people lived, and, perhaps, the wealth of the inhabitants.

Levels of Investigation and Analysis

Paint analysis using a microscope
Paint analysis using a microscope. Photo by Sean Gallup/Getty Images News Collection/Getty Images (cropped)

Like the practice of a medical doctor, a professional architectural investigator should begin with non-invasive observation and move to more invasive "sub-surface" examination if warranted. "All projects should begin with the simplest, non-destructive processes," says the author, "and proceed as necessary." Reconnaissance is the preliminary surveying step. Professional investigators can make important determinations in just a 2 to 4 hour visual go-through of the property.

A very interesting practice is the laboratory analysis of paint and plaster materials and applications. Samples are examined microscopically, and, like a medical test, a report is presented to be added to other investigative data points.

"Evidence, questions, and hypotheses must be continually evaluated during investigation," explains preservationist Travis C. McDonald, Jr.  "Like a detective constructing a case, an investigator must sort out information to get at 'the facts.' Yet, are the 'facts' conclusive at any time?"

Documenting Findings

Removing damaged plaster from wood lath in ceiling of Robie House
Removing damaged plaster from wood lath in ceiling of Robie House. Photo by Frank Lloyd Wright Preservation Trust/Archive Photos Collection/Getty Images (cropped)

Before the Robie House was turned over to the Frank Lloyd Wright Preservation Trust in 1997, Wright's most famous prairie style house had been remodeled, with little written documentation about the changes. Architects were hired to investigate, analyze, and develop a restoration plan, which included replacing damaged plaster in the front hallway.

Architects do more than design and build. Studying architecture offers many opportunities, including documenting history. If historic preservation appeals to you, professional architectural investigations can be a worthwhile career. For every project, the investigator is able to, essentially, write a book about the structure and what went on there. The document may add value to your house, if you ever want to sell, but it's most always part of the process for any historic renovation and preservation. At the professional level, a template-based document called the Historic Structure Report is often the result of a thorough architectural investigation. The report may be used to raise funds for extensive and expensive historic preservation projects. The Preparation and Use of Historic Structure Reports is explained in Preservation Brief 43.

Examples of Historic Structure Reports:

Learn More:

  • How to Write a Historic Structure Report by David Arbogast, Norton, 2011

Summary and Reading List

Robie House restoration of entry hall plaster ceiling
Robie House restoration of entry hall plaster ceiling. Photo by Frank Lloyd Wright Preservation Trust/Archive Photos Collection/Getty Images (cropped)

"The expressed goal of historic preservation is to protect and preserve materials and features that convey the significant history of a place," sums up Travis C. McDonald, Jr. in Preservation Brief 35. A well-done architectural investigation helps achieve that goal.

  • Bullock, Orin M. Jr., The Restoration Manual. Norwalk, CT.: Silvermine Publishers, 1966
  • Burns, John A., editor. Recording Historic Structures. Washington, D.C.: The AIA Press, 1989
  • Howard, Hugh. How Old Is This House?  New York: Noonday Press, 1989
  • Kitchen, Judith L., Caring For Your Old House. Washington, D.C.: The Preservation Press, 1991

About Preservation Brief 35:

Understanding Old Buildings: The Process of Architectural Investigation was written by Travis C. McDonald, Jr. for the Technical Preservation Services, National Park Service, U.S. Department of the Interior. Preservation Brief 35 was first published September 1994.

Source: Preservation Brief 35 by Travis C. McDonald. Download the PDF version of Understanding Old Buildings, with more photos and diagrams, from the National Park Services website at