Historic Preservation - Technical Procedures

General Gsa Maintenance Guidelines
Procedure code:
Maint, Rpr And Alteration Of Historic Bldgs - Gsa/Pbs
General Requirements
Last Modified:
General Gsa Maintenance Guidelines
Last Modified:


This standard includes general GSA guidelines to consider when
maintaining historic materials.

Reference: National Park Service Preservation Brief 47: Maintaining the Exterior

of Small and Medium Size Historic Buildings



Proper custodial care counters the forces that cause deterioration
of the building fabric, such as: erosion and abrasion; chemical
deterioration; corrosion and mold; birds, insects, and plant materials; and the effects of the most
unpredictable factor in building care, human behavior.

Buildings require cleaning because weathering and human activity
deposit potentially harmful particles on surfaces.  Dirt particles
abet abrasion and are often a factor in chemical deterioration
processes.  Occasionally, special techniques are required to
counteract the electrostatic attraction between dirt and certain
surfaces, or to arrest or reverse various ongoing chemical changes
caused by dirt on sensitive materials.

In historic buildings, where the materials are older, less
resistant to abrasive and chemical action than their contemporary
counterparts, and frequently irreplaceable, special consideration
of the following custodial guidelines is warranted:

1.   Understand the nature of both the dirt and the surface to be
    cleaned before proceeding.  Dry cleaning processes (e.g.,
    dusting, polishing, vacuuming, etc.) will remove over half of
    the dirt, usually at little risk to the structure; wet
    cleaning (e.g., mopping, washing, etc.) including the use of
    soaps, detergents, polishes and other compounds to suspend and
    emulsify dirt particles, are necessary to clean the other

2.   Use the mildest workable method and cleaning solution in each
    instance; this may require more time or effort.

3.   Refer to historical precedents regarding how the materials
    have been cared for before choosing a new custodial process.

4.   Research and test the suitability of new products before
    permitting their widespread use on an historic building.  Seek
    the experiences of others before proceeding.  Begin work in
    the less sensitive, less valuable areas of the structure.

5.   Remember that decisions involving the care of historic
    buildings frequently involve the lesser of two evils; in some
    instances, historic materials that might be damaged by
    repeated cleaning may be better preserved if they remain
    dirtier than custodial standards would otherwise permit.

6.   Clean ONLY when a useful purpose is served; do not clean
    historic materials simply because they are old.

In general, the standard custodial practices of the General
Services Administration (refer to GSA Custodial Management
Handbook, PBS P 5810.2A) are well suited to the normal demands of
interior cleaning in historic buildings, and most external cleaning
problems as well (e.g., cleaning of glass, architectural metals,
etc.; consult Part 3 of the Guide for the special case of masonry

The procedures and policies of the General Services Administration
regarding the maintenance and repair of conventional buildings
(refer to HB, Building Maintenance Management, PBS P 5850.1A) are
also applicable to GSA's historic buildings although some changes
in emphasis are frequently necessary.

Because a range of alternatives must be considered when confronting
any maintenance or repair problem, the following questions are

1.   Has the problem and its remedy been identified or only the

2.   Are the resources available to solve the problem on a long-term basis?

3.   If not, are visually and technically acceptable interim
    alternatives available?

4.   What are the implications of taking no action or delaying
    action until a better solution or additional resources are at

5.   Does the contemplated maintenance or repair action involve the
    irreversible effect or destruction of significant fabric?  Is
    the projected benefit worth the risk?

6.   Can the situation which caused the problem be remedied by
    changing the cause rather than treating its result (e.g.,
    reducing the load to eliminate the overstress; changing the
    use pattern to diminish wear and tear, etc.)?

7.   What can be learned from maintenance or repair records about
    previous attempts to solve the problem?  Have other GSA
    personnel confronted comparable problems in similar buildings?

                         END OF SECTION

Last Reviewed 2012-11-30