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Understanding Old buildings:
The Process of Architectural Investigation
Travis C. McDonald, Jr.
If you have ever felt a
sense of excitement and mystery going inside an old
building-whether occupied or vacant-it is probably because
its materials and features resonate with the spirit of past
people and events. Yet excitement about the unknown is
heightened when a historic structure is examined
architecturally, and its evolution over time emerges with
increasing clarity to reveal the lives of its occupants.
Architectural investigation is the critical first step in
planning an appropriate treatment-understanding how a
building has changed over time and assessing levels of
deterioration.
Whether as a home owner
making sympathetic repairs, a craftsman or contractor
replacing damaged or missing features, or a conservator
reconstituting wood or restoring decorative finishes, some
type of investigative skill was used to recognize and solve
an architectural question or explain a difficult aspect of
the work itself.
To date, very little has
been written for the layman on the subject of architectural
investigation. This Preservation Brief thus addresses the
often complex investigative process in broad,
easy-to-understand terminology. The logical sequence of
planning, investigation and analysis presented in this Brief
is applicable to all buildings, geographic locations,
periods, and construction types. It is neither a "how to" nor
an exhaustive study on techniques or methodologies; rather,
it serves to underscore the need for meticulous planning
prior to work on our irreplaceable cultural resources.
Determining
the Purpose of Investigation
Both the purpose and
scope of investigation need to be determined before
formulating a particular approach. For example, investigation
strictly for research purposes could produce information for
an architectural survey or for an historic designation
application at the local, state or national level.
Within the framework of
The Secretary of the Interior's Standards for the
Treatment of Historic Properties, investigation is
crucial for "identifying, retaining, and preserving the form
and detailing of those architectural materials and features
that are important in defining the historic character" of a
property, whether for repair or replacement. A
rehabilitation
project, for instance,
might require an investigation to determine the historic
configuration of interior spaces prior to partitioning a room
to meet a compatible new use. Investigation for preservation
work can entail more detailed information about an entire
building, such as determining the physical sequence of
construction to aid in interpretation. Investigation for a
restoration project must be even more comprehensive in order
to re-capture the exact form, features, finishes, and
detailing of every component of the building.
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.
Historical
Research. Primary historical research of an old
building generally encompasses written, visual and oral
resources that can provide valuable site-specific
information. Written resources usually include letters, legal
transactions, account books, insurance policies,
institutional papers, and diaries. Visual resources consist
of drawings, maps, plats, paintings and photographs. Oral
resources are people's remembrances of the past. Secondary
resources, comprised of research or history already compiled
and written about a subject, are also important for providing
a broad contextual setting for a project.
Historical research
should be conducted well in advance of physical
investigation. This allows time for important written,
visual, and oral information to be located, transcribed,
organized, studied and used for planning the actual
work.
A thorough scholarly
study of a building's history provides a responsible
framework for the physical investigation; in fact, the
importance of the link between written historical research
and structural investigation cannot be overestimated. For
example, the historical research of a building through deed
records may merely determine the sequence of owners. This, in
turn, aids the investigation of the building by establishing
a chronology and identifying the changes each occupant made
to the building. A letter may indicate that an occupant
painted the building in a certain year; the courthouse files
contain the occupant's name; paint analysis of the building
will yield the actual color. Two-dimensional documentary
research and three-dimensional physical investigation go
hand-in-hand in analyzing historic structures. The quality
and success of any restoration project is founded upon the
initial research.
Documentation. A building should be
documented prior to any inventory, stabilization or
investigative work in order to record crucial material
evidence. A simple, comprehensive method is to take 35 mm
photographs of every wall elevation (interior and exterior),
as well as general views, and typical and unusual details.
The systematic numbering of rooms, windows and doors on the
floor plan will help organize this task and also be useful
for labeling the photographs. Video coverage with annotated
sound may supplement still photographs. Additional methods of
documentation include written descriptions, sketches, and
measured drawings.
Significant structures,
such as individually listed National Register properties or
National Historic Landmarks, benefit from professional
photographic documentation and accurate measured drawings.
Professionals frequently use The Secretary of the
Interior's Standards and Guidelines for Architectural and
Engineering Documentation: HABS/HAER Standards. It
should be remembered that the documents created during
investigation might play an unforeseen role in future
treatment and interpretation. Documentation is particularly
valuable when a feature will be removed or altered.
Inventory.
The historic building and its components should be carefully
inventoried prior to taking any action; premature clean-up of
a structure or site can be a mistake. A careful look at all
spaces in and around a building may reveal loose
architectural artifacts, fragile evidence or clues to
historic landscape features. This thorough observation
includes materials and features which have fallen off due to
deterioration, fragments removed and stored in basements,
attics or outbuildings, and even materials which have
seemingly been discarded.
In the beginning,
anything that seems even remotely meaningful should be saved.
A common mistake is to presume to know the value of artifacts
or features at the beginning of a project. Even if the period
of significance or interpretation is known from the
beginning, evidence from all periods should be protected.
Documentation for future study or use includes labeling and,
if possible, photographing prior to storage in a secure
place.
Stabilization. In many cases, emergency
stabilization is necessary to ensure that a structure does
not continue to deteriorate prior to a final treatment or to
ensure the safety of current occupants, investigators, or
visitors. Although severe cases might call for structural
remedies, in more common situations, preliminary
stabilization would be undertaken on a maintenance level.
Such work could involve installing a temporary roof covering
to keep water out; diverting water away from foundation
walls; removing plants that hold water too close to the
walls; or securing a structure against intruding insects,
animals and vandals.
An old building may
require temporary remedial work on exterior surfaces such as
reversible caulking or an impermanent, distinguishable
mortar. Or if paint analysis is contemplated in the future,
deteriorated paint can be protected without heavy scraping by
applying a recognizable "memory" layer over all the historic
layers. Stabilization adds to the cost of any project, but
human safety and the protection of historical evidence are
well worth the extra money.
Investigators
and Investigative Skills
General and
Specialized Skills. The essential skill needed for
any level of investigation 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!
Next, whether acquired in a university or in a practical
setting, an investigator should have a good general knowledge
of history, building design history and, most important,
understand both construction and finish technologies.
But it is not enough to
know architectural style and building technology from a
national viewpoint; the investigator needs to understand
regional and local differences as well.
While investigative
skills are transferable between regions and chronological
periods, investigators must be familiar with the
peculiarities of any given building type and geographical
area.
Architectural survey and
comparative fieldwork provides a crucial database for
studying regional variations in historic buildings. For
example, construction practices can reflect shared
experiences of widely diverse backgrounds and traditions
within a small geographical area. Contemporary construction
practice in an urban area might vary dramatically from that
of rural areas in the same region. Neighbors or builders
within the same small geographical area often practice
different techniques of constructing similar types of
structures contemporaneously. Reliable dating clues for a
certain brick bond used in one state might be unreliable for
the same period in a different state. Regional variation
holds true for building materials as well as
construction.
Finally, even beyond
regional and local variation, an investigator needs to
understand that each building has its own unique history of
construction and change over time. Form, features, materials
and detailing often varied according to the tastes and
finances of both builder and supplier;
construction quality and
design were also inconsistent, as they are today.
Specialists on a
Team. Because architectural investigation requires a
wide range of knowledge and many different skills, various
people are likely to interact on the same project. While
homeowners frequently execute small-scale projects, more
complex projects might be directed by a craftsman, an
architect or a conservator. For large-scale projects, a team
approach may need to be adopted, consisting of professionals
interacting with additional consultants. Consulting
specialists may include architectural historians,
architectural conservators, craftsmen, historic finish
analysts, historians, archeologists, architects, curators,
and many others. The scope and needs of a specific project
dictate the skills of key players.
Architectural
investigation often includes the related fields of landscape
and archeological investigation. Landscape survey or analysis
by horticulturists and landscape architects identify
pre-existing features or plantings or those designed as
separate or complementary parts of the site. Both above and
below-ground archeology contribute information about missing
or altered buildings, construction techniques, evidence of
lifestyle and material culture, and about the evolution of
the historic landscape itself.
Showing
the Evolution of an 18th Century Farmhouse
(Sidebar)
Most structures evolve
over time. Houses, perhaps more than other building types,
are often subjected to a full range of change that reflects a
wide variety of solutions for creating new living space or
eliminating outmoded spaces. Architectural changes to
historic houses can be studied through the close physical
examination of construction and decorative details. Tracing
the history of alterations over time is tantamount to
"excavating" the structure, somewhat like an archeological
investigation. By peeling back its layers of occupation and
assembling plan changes, a sequence of consecutive solutions
or transformations can be developed that reveals people's
ongoing desires for new and improved living
conditions.
The example of a Sussex
County, Delaware, house-from ca. 1790 to the early
1900s-illustrates how complicated the pattern of change over
time can become in outlining an individual house history. The
Hunter Farm House was built in the 18th century as a
double-cell, double-pile, half-passage plan (a). Two bays
across the front and two stories tall, the house possessed
back-to-back corner fireplaces with fully paneled fireplace
walls in the front and back rooms. A stair in the rear
passage provided access to the second floor. A one-story,
two-room shed that was attached to the gable wall farthest
from the fireplace was accessed by a low door leading from
the front room.
During the course of its
history, the house was altered at least three times. The
five-part illustration shows the house's transformation from
an open plan to a Georgian plan and the subsequent addition
and re-arrangement of service rooms for cooking and storage.
The first remodeling occurred in the early nineteenth century
when the lean-to shed was removed, and a two-story,
single-pile, two-bay house was moved up and attached to the
northwest gable of the existing building (b). (The newly
attached building had originally been furnished with opposing
doors and windows on the front and back facades, a fireplace
on the southeast gable, and double windows on the opposite
end.) When the second building was joined to the first, the
fireplace in the newer building was relocated to the opposite
gable; the front door in the older house moved to a more
central position; and a center-hall plan created with a
roughly symmetrical front elevation ©. A subsequent
alteration later in the nineteenth century included the
addition of a one-story rear service ell (d). Finally, in the
early 1900s, the one-story service wing was increased. During
this last remodeling, the large kitchen hearth was demolished
and replaced with a stove and new brick flue (e). Sidebar:
Bernard L. Herman and Gabrielle M. Lanier, University of
Delaware. Drawings by: Center for Historic Architecture and
Engineering, University of Delaware.
Architectural Evidence: Studying the Fabric of the
Historic Building:
Original
Construction and Later Changes. Research prior to
investigation may have indicated the architect, builder or a
building's date of construction. In the absence of such
information, architectural histories and field guides to
architectural style can help identify a structure's age
through its form and style.
Any preliminary date,
however, has to be corroborated with other physical or
documentary facts. Dates given for stylistic periods are
general and tend to be somewhat arbitrary, with numerous
local variations. Overall form and style can also be
misleading due to subsequent additions and alterations. When
the basic form seems in conflict with the details, it may
indicate a transition between styles or that a style was
simply upgraded through new work.
The architectural
investigation usually determines original construction
details, the chronology of later alterations, and the
physical condition of a structure. Most structures over fifty
years old have been altered, even if only by natural forces.
People living in a house or using a building for any length
of time leave some physical record of their time there,
however subtle.
A longer period of
occupancy generally counts for greater physical change.
Buildings acquire a "historic character" as changes are made
over time.
Changes to architectural
form over time are generally attributable to material
durability, improvement in convenience systems, and
aesthetics. First, the durability of building materials is
affected by weathering, temperature and humidity, by
disasters such as storms, floods or fire, or by air pollution
from automobiles and industry. Second, changes in
architectural form have always been made for convenience'
sake-fueled by technological innovations-as people embrace
better lighting, plumbing, heating, sanitation, and
communication. People alter living spaces to meet changing
family needs. Finally, people make changes to architectural
form, features, and detailing to conform to current taste and
style.
Looking More Closely at Historic Building Materials and
Features
Although brick or wood
frame buildings are the most common in this country, similar
sets of characteristics and questions can be established for
examining log, adobe, steel, or any other
material.
Masonry.
Studying historic brickwork can provide important information
about methods of production and construction. For example,
the color, size, shape and texture of brick reveals whether
it was hand molded and traditionally fired in a clamp with
hardwoods, or whether it was machine molded and fired in a
kiln using modern fuels. Similarly, the principal component
part of masonry mortar, the lime or cement, reveals whether
it was produced in a traditional or modern manner. Certain
questions need to be asked during investigation. Is the
mortar made with a natural or a Portland cement? If a natural
cement, did it come from an oyster shell or a limestone
source? Is it hydrated or hydraulic? As a construction unit,
brick and mortar further reveal something about the time,
place and human variables of construction, such as the type
of bond, special brick shapes, decorative uses of glazed or
rubbed brick, coatings and finishes, and different joints,
striking and tooling. Does the bond conform with neighboring
or regional buildings of the same period? Does the pattern of
"make up" bricks in a Flemish Bond indicate the number of
different bricklayers? What is the method of attaching wood
trim to the masonry? The same types of questions related
to
production and
construction characteristics can be applied to all types of
masonry work, including stone, concrete, terra cotta, adobe
and coquina construction. A complete survey undertaken during
"surface mapping" can outline the materials and construction
practices for the various periods of a structure,
distinguishing the original work as well as the additions,
alterations, and replacements.
Wood.
Buildings constructed with wood have a very different set of
characteristics, requiring a different line of questioning.
Is the wooden structural system log, timber frame, or balloon
frame construction? Evidence seen on the wood surface
indicates whether production was by ax, adze, pit saw, mill
saw (sash or circular), or band saw. What are the varying
dimensions of the lumber used? Finished parts can be sawn,
gouged, carved, or planed (by hand or by machine). Were they
fastened by notching, mortise and tenon, pegs, or nailing? If
nails were used, were they wrought by hand, machine cut with
wrought heads, entirely machine cut, or machine wire nails?
For much of the nineteenth century the manufacture of nails
underwent a series of changes and improvements that are
dateable, allowing nails to be used as a tool in establishing
periods of construction and alteration. Regardless of region
or era, the method of framing, joining and finishing a wooden
structure will divulge something about the original
construction, its alterations, and the practices of its
builders. Finally, does some of the wood appear to be re-used
or re-cycled? Re-used and reproduction materials used in
early restoration projects have confused many investigators.
When no identification record was kept, it can be a problem
distinguishing between materials original to the house and
later replacement materials.
Roofs.
Exterior features are especially prone to alteration due to
weathering and lack of maintenance. Even in the best
preserved structures, the exterior often consists of replaced
or repaired roofing parts. Roof coverings typically last no
more than fifty years. Are several generation of roof
coverings still in place? Can the layers be identified? If
earlier coverings were removed, the sheathing boards
frequently provide clues to the type of covering as well as
missing roof features. Dormers, cupolas, finials, cresting,
weathervanes, gutters, lightning rods, skylights,
balustrades, parapets and platforms come and go as taste,
function and maintenance dictate. The roof pitch itself can
be a clue to stylistic dating and is unlikely to change
unless the entire roof has been rebuilt. Chimneys might hold
clues to original roof pitch, flashings, and roof feature
attachments. Is it possible to look down a chimney and count
the number of flues? This practice has occasionally turned up
a missing fireplace. In many parts of the country,
nineteenth-century roof coverings evolved from wooden
shingles or slate shingles, to metal shingles, to sheet
metal, and still later in the twentieth century, to asphaltic
or asbestos shingles. Clay tiles can be found covering roofs
in seventeenth and eighteenth-century settlements of the east
coast as well as western and southwestern Spanish settlements
from the same period. Beyond the mid-nineteenth century, and
into the twentieth, the range and choice of roof coverings
greatly expanded.
Floors. In
addition to production and construction clues, floors reveal
other information about the interior, such as circulation
patterns, furniture placement, the use of carpets, floor
cloths, and applied floor finishes. Is there a pattern of
tack holes? Tacks or tack holes often indicate the position
and even the type of a floor covering. A thorough
understanding of the seasonal uses of floor coverings and the
technological history of their manufacture provide the
background for identifying this type of evidence.
Walls.
Walls and their associated trim, both outside and inside,
hold many clues to the building's construction and changes
made over time. The overall style of moldings, trim and
finishes, and their hierarchical relationship, can help
explain original construction as well as room usage and
social interaction between rooms. Holes, scars, patches,
nails, nail holes, screws and other hardware indicate former
attachments. Are there "ghosts," or shadow outlines of
missing features, or trim attachments such as bases, chair
rails, door and window casings, entablatures, cornices,
mantels and shelves? Ghosts can be formed by paint, plaster,
stucco, wear, weathering or dirt. Interior walls from the
eighteenth and early nineteenth-century were traditionally
plastered after grounds or finished trim was in place,
leaving an absence of plaster on the wall behind them.
Evidence of attachments on window casings can also be helpful
in understanding certain interior changes. Other clues to
look for include the installation of re-used material brought
into a house or moved about within a house; worker's or
occupant's graffiti, especially on the back of trim; and
hidden finishes or wallpaper stuck in crevices or underneath
pieces of trim. Stylistic upgrading often resulted in the
re-use of outdated trim for blocking or shims. Unexpected
discoveries are particularly rewarding. Investigators
frequently tell stories about clues that were uncovered from
architectural fragments carried off by rats and later found,
or left by workers in attics, between walls and under
floors.
Attics and
Basements. Attics and basements have been known as
collection points for out-of-date, out-of-style and cast-off
pieces such as mechanical systems, furnishings, family
records and architectural fragments. These and other
out-of-the-way places of a structure provide an excellent
opportunity for non-destructive investigation. Not only are
these areas where structural and framing members might be
exposed to view, they are also areas which may have escaped
the frequent alteration campaigns that occur in the more
lived-in parts of a building. If a building has been raised
or lowered in height, evidence of change would be found in
the attic as well as on the exterior. Evidence of additions
might also be detected in both the attic and the basement.
Attics frequently provide a "top-side" view at the ceiling
below, revealing its material, manner of production and
method of attachment. A "bottom-side" view of the roof
sheathing or roof covering can be seen from the attic as
well.
Basements generally
relate more to human service functions in earlier buildings
and to mechanical services in more recent eras. For example,
a cellar of an urban 1812 house disclosed the following
information during an investigation: first period bell
system, identification of a servant's hall, hidden fireplace,
displacement of the service stairs,
identification of a
servants' quarters, an 1850s furnace system, 1850s gas and
plumbing systems, relocation of the kitchen in 1870, early
use of 1890s concrete floor slabs and finally, twentieth
century utility systems. While the earliest era had been
established as the interpretation period, evidence from all
periods was documented in order to understand and interpret
how the house evolved or changed over time.
Mechanical,
Electrical, Plumbing and Other Systems. Systems of
utility and convenience bear close scrutiny during
investigation. All historic buildings inhabited and used by
people reveal some association, at the very minimum, with the
necessities of lighting, climate control, water, food
preparation, and waste removal. Later installations in a
building may include communication, hygiene, food storage,
security, and lightning protection systems. Other systems,
such as transportation, are related to more specific
functions of commercial or public structures. Although
research into the social uses of rooms and their furnishings
has borne many new studies, parallel research into how people
actually carried out the most mundane tasks of everyday life
has been fairly neglected. Utility and convenience systems
are most prone to alteration and upgrading and, at the same
time, less apt to be preserved, documented or re-used.
Understanding the history or use of a building, and the
history of systems technology can help predict the physical
evidence that might be found, and what it will look like
after it is found.
Conducting
the Architectural Investigation
Architectural
investigation can range from a simple one hour walk-through
to a month long or even multi-year project-and varies from
looking at surfaces to professional sub-surface examination
and laboratory work.
All projects should begin
with the simplest, non-destructive processes and proceed as
necessary. The sequence of investigation starts with
reconnaissance and progresses to surface examination and
mapping, sub-surface non-destructive testing, and various
degrees of sub-surface destructive testing.
Reconnaissance. An initial reconnaissance
trip through a structure-or visual overview-provides the most
limited type of investigation. But experienced investigators
accustomed to observation and analysis can resolve many
questions in a two-to-four hour preliminary site visit. They
may be able to determine the consistency of the building's
original form and details as well as major changes made over
time.
Surface
Mapping. The first step in a thorough, systematic
investigation is the examination of all surfaces. Surface
investigation is sometimes called "surface mapping" since it
entails a minute look at all the exterior and interior
surfaces. The fourfold purpose of surface mapping is to
observe every visible detail of design and construction;
develop questions related to evidence and possible
alterations; note structural or environmental problems; and
help develop plans for any further investigation. Following
investigation, a set of documentary drawings and photographs
is prepared which record or "map" the evidence.
While relying upon senses
of sight and touch, the most useful tool for examining
surfaces is a high-powered, portable light used for
illuminating dark spaces as well as for enhancing surface
subtleties. Raking light at an angle on a flat surface is one
of the most effective means of seeing evidence of
attachments, repairs or alterations.
Non-Destructive
Testing. The next level of investigation consists of
probing beneath surfaces using non-destructive methods.
Questions derived from the surface mapping examination and
analysis will help determine which areas to probe.
Investigators have perfected a number of tools and techniques
which provide minimal damage to historic fabric. These
include x-rays to penetrate surfaces in order to see nail
types and joining details; boroscopes, fiber optics and small
auto mechanic or dentists' mirrors to look inside of tight
spaces; and ultra violet or infra-red lights to observe
differences in materials and finishes. The most advanced
technology combines the boroscope with video cameras using
fiber optic illumination. In addition to the more common use
of infra-red photography, similar non-destructive techniques
used in archeological investigations include remote sensing
and ground-penetrating radar.
Small material samples of
wood, plaster, mortar, or paint can also be taken for
laboratory analysis at this stage of investigation. For
instance, a surface examination of a plaster wall using a
raking light may show clear evidence of patching which
corresponds to a shelf design. Were the shelves original or a
later addition? A small sample of plaster from the patched
area is analyzed in the laboratory and matches plaster
already dated to a third period of construction. A probe
further reveals an absence of first period plaster on the
wall underneath. The investigator might conclude from this
evidence that the shelves were an original feature and that
the plaster fill dates
their removal and patching
to a third period of construction.
Destructive
Testing. Most investigations require nothing more
than historical research, surface examination and
non-destructive testing. In very rare instances the
investigation may require a sub-surface examination and the
removal of fabric. Destructive testing should be carried out
by a professional only after historical research and
surface mapping have been fully accomplished and only
after non-destructive testing has failed to produce the
necessary information. Owners should be aware that the work
is a form of demolition in which the physical record may be
destroyed. Sub-surface examination begins with the most
accessible spaces, such as retrofitted service and mechanical
chases; loose or previously altered trim, ceilings or floor
boards; and pieces of trim or hardware which can be easily
removed and replaced.
Non-destructive testing
techniques do not damage historic fabric. If non-destructive
techniques are not sufficient to resolve important questions,
however, small "windows" can be opened in surface fabric at
predetermined locations to see beneath the surface. This type
of subsurface testing and removal is sometimes called
"architectural archeology" because of its similarity to the
more well-known process of trenching in archeology. The
analogy is apt because both forms of archeology use a method
of destructive investigation.
Photographs, video and
drawings should record the before, during and after evidence
when the removal of historic fabric is necessary. The
selection and sequence of material to be removed requires
careful study so that original extant fabric remains in
situ if possible. If removed, original fabric should be
carefully put back or labeled and stored. At least one
documentary patch of each historic finish should be retained
in situ for future research. Treatment and
interpretation, no matter how accurate, are usually not
final; treatment tends to be cyclical, like history, and
documentation must be left for future generations, both on
the wall and in the files.
Laboratory
Analysis. Laboratory analysis plays a scientific role
in the more intuitive process of architectural investigation.
One of the most commonly known laboratory procedures used in
architectural investigation is that of historic paint
analysis. The chronology and stratigraphy of applied layers
can establish appropriate colors, finishes, designs or wall
coverings. When conducted simultaneously with architectural
investigation, the stratigraphy of finishes, like that of
stratigraphic soils in archeology, helps determine the
sequence of construction or alterations in a building.
Preliminary findings from in situ examinations of
painted finishes on walls or trim are common, but more
accurate results come from extensive sampling and microscopic
laboratory work using chemical analysis and standardized
color notations. Consultants without the proper knowledge
have been known to cause far more harm than good.
Mortar and plaster
analysis often provide a basis for dating construction with
minimal intervention. Relatively small samples of the
lime-based materials can be chemically separated into their
component parts of sands and fines, which are then visually
compared to equivalent parts of known or dated samples. A
more thorough scientific approach may be used to accurately
profile and compare samples of other materials through
elemental analysis. Two similar methods in common use are
Neutron Activation and Energy Dispersive Spectroscopy (EDS).
Neutron Activation identifies the sample's trace elements by
monitoring their response to neutron bombardment. EDS
measures the response to electron bombardment through the use
of an electron microscope. In both tests, the gathered
information is plotted and matched with the reactions of
known elements. The results provide a quantitative and
qualitative profile of the sample's elemental components for
use in further comparisons.
Dendrochronology presents
a minimally destructive process for dating wooden members.
Also called tree ring dating, this process relies on the
comparative wet and dry growth seasons of trees as seen in
their rings via a core sample. This technique has two
limitations: a very extensive data base must be compiled for
climatic conditions over a long span of years and matched
with corresponding tree ring samples; and the core samples
can only be taken from timber which still has a bark edge.
Simple identification of wood species during an investigation
can be determined from small samples sent to a forest
products laboratory.
After
Architectural Investigation: Weighing the Evidence
Evidence, questions, and
hypotheses must be continually evaluated during
investigation. 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?
Observations made during
the surface mapping may identify random features. These
features begin to form patterns; then, sets of patterns,
perhaps representing alterations from multiple eras, begin to
appear. If the right questions are not asked, the evidence
can remain hidden. Hypotheses are formed, questioned, tested,
re-formed and either rejected or substantiated. This process
is repeated as more "facts" are uncovered and questions
asked. Eventually the evidence seems conclusive. These
conclusions, in turn, may lead to re-examination, more
historical research, and the advice of specialized
consultants. At some point, treatment generally follows based
on the collective, educated conclusions of an entire
professional team.
Keeping
a Responsible Record for Future Investigators
The evidence collected
during investigation, and any conclusions which can be drawn
from it, should be documented in a written report. The
complexity of a project dictates the complexity of the
resulting record. It may be wise to maintain a report in an
expandable format if long or extensive work is
expected-additional evidence will undoubtedly need to be
incorporated that alters previous conclusions. Reports tend
to range from annotated photographs in loose-leaf binders to
full-length bound "books."
Putting findings and
conclusions in an accessible form helps those who are
planning treatment. For example, a rehabilitation project may
require documentation to satisfy grant funding or tax credit
program requirements; preservation and restoration projects
always need careful documentation to guide the work. After
work, the investigation report and notes on the treatment
itself are made into a permanent file record. Whether or not
work is being planned, the architectural investigation report
will always be of value to future researchers or owners of
the building.
The most common
professional document is called an Historic Structure
Report. This invaluable tool for preservation typically
contains historical as well as physical information. Sections
include a history of the building, an architectural
description of the original structure and changes made over
time, the results of all investigations, a record of current
conditions or problems, of past repairs and treatments, and
recommendations for current and future action. They are
seldom definitive; thus, research is a continuing
process.
Conclusion
Architectural
investigation plays a critical role in making responsible
decisions about treating and interpreting historic buildings.
A successful project to research, inventory, document, and
ultimately treat and interpret a building is directly linked
to the knowledge and skills of
architectural
investigators and other historic preservation specialists.
The expressed goal of historic preservation is to protect and
preserve materials and features that convey the significant
history of a place. Careful architectural
investigation-together with historical research-provides a
firm foundation for this goal.
Bibliography
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.
Howe, Barbara J., Dolores
A. Fleming, Emory L. Kemp, and Ruth Ann Overbeck. Houses
and Homes: Exploring Their History. Nashville, TN.:
American Association for State and Local History,
1987.
Judd, Henry A., Before
Restoration Begins. Nashville, TN.: American Association
for State and Local History, 1973.
Kitchen, Judith L.,
Caring For Your Old House. Washington, D.C.: The
Preservation Press, 1991.
Seale, William,
Recreating the Historic House Interior. Nashville,
TN.: American Association for State and Local History,
1979.
Secretary of the
Interior's Standards for the Treatment of Historic
Properties. Washington, D.C.: Preservation Assistance
Division, National Park Service, U.S. Department of the
Interior, 1992.
Secretary of the
Interior's Standards and Guidelines for Architectural and
Engineering Documentation: HABS/HAER Standards. Washington,
D.C.: HABS/HAER, National Park Service, U.S. Department of
the Interior, 1990.
Acknowledgements
Travis C. McDonald,
Jr., is an architectural historian who serves as the
Restoration Coordinator at Thomas Jefferson's Poplar Forest
near Lynchburg, Virginia. He respectively dedicates this work
to three masters of architectural investigation: Henry A.
Judd, former Chief Historical Architect of the National Park
Service; Lee H. Nelson, former Chief, Preservation Assistance
Division NPS; and Paul E. Buchanan, former Director of
Architectural Research at the Colonial Williamsburg
Foundation. The author gratefully acknowledges the following
professionals for their help in reviewing this manuscript:
Edward A. Chappell, Colonial Williamsburg; E. Blaine Cliver,
Preservation Assistance Division NPS; Stanley O. Graves,
National Conference of State Historic Preservation Officers;
Bernard L. Herman, University of Delaware; H. Ward Jandl,
Preservation Assistance Division NPS; Hugh C. Miller,
Virginia State Historic Preservation Office; Orlando Ridout
V, Maryland Historical Trust; William Seale; and professional
staff members of the National Park Service. Timothy A.
Buehner served as project coordinator and Kay D. Weeks as
project editor. Washington, D.C. September, 1994
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