FEMA correspondence regarding historic building cleaning treatments, February 2002

NYC 9/11 Public Portal Document IYIHR. I7. IVVZ I I : L t IV1 IV. I yL r. L0

Requirements and Performance Standards Removing Applied Paint (Sig~page) from Masonry

I. Requirements

_General: All work related to historic buildings shall comply with the Secretary of the Interior's Standards for the Treatment of Historic Properties. Treatment approaches will be in• the "gentlest means possible," and all methods should be material and building specific. Removal of Applied Paint (signage) from masonry should be done as soon as possible. Programs for the removal of applied pain(firom historic building fabric shall be developed on a case-by-case basis with regard to each building and all associated building materials. Harsh treatments and inappropriate cleaning methods, including abrasive cleaning and certain chemical applications, can permanently damage significant historic building fabric and character-defining features. Traditional abrasive applications such as "sand-blasting" and high-pressure water cleaning shall not de used.

TT. Performance.Standards

Qualified Contractor(s)/Consultant(s): A- qualified.professional such as a historic preservation or. a building conservation expert shall be consulted to develop an appropriate for each building. A qualified contractor or building conservator, removal program experienced in the removal of applied •paint (signage) and cleaning of historic buildings shall be used to perform work. Testing: Prior to the removal of applied paint identify the paint type and the substrate to which the paint is applied. Identification of the paint type and substrate material (e.g. stone, cast stone, brick, terra cotta) combined with professional interpretation of test results will aid in the determination of the most appropriate removal method. After a cleaning program is method shall be tested and evaluated by a qualified professional prior selected, the to application. Each building and building material shall be assessed and tested prior to developing and implementiing cleaning programs. It is expected that several methods of removal will be tested before an appropriate removal method is found.

WTC Site Specific Considerations:

o Masonry surfaces shall be free of dust prior to implementing a removal program. It is possible, based upon composition of the particulates generated by the disaster, that the dust and/or debris on the facade may chemically react with applications and masonry substrate during the cleaning process, creating deposits that will cause problems to the building over time. Dust and debris deposited on buildings should be tested and, if determined necessary, properly removed prior to the application of water or liquid cleaning agents. (see Performance Standards for CIeaning Masonry Exteriors).

o The Applicant should ensure that potential disaster related damages to the building which may include, but are not limited to, openings in building facades, dust on building materials, cracks, open mortar joints, and weakened or damaged materials are identified by a qualified professional prior to cleaning the facade. Precautions should be taken prior

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NYC-WTC 000093771