Masonry
The intent
of these guidelines as they pertain to masonry is to preserve the historic
appearance and to prevent
accelerated
deterioration of masonry construction. Modern techniques and materials used in
masonry work
today are
damaging to the softer materials found in historic brick. Refer to the Newburyport Historical
Commission’s
ADVISORY TO CONTRACTORS AND HOMEOWNERS ON MASONRY for further information
on acceptable
methods of cleaning and pointing historic brick.
Use mortar
compatible with historic masonry. DO NOT repoint a historic soft mortar with
mortar
containing primarily
Portland cement. Mortar with Portland
cement sets too hard and will cause the
historic masonry
to deteriorate.
Clean only
when it is necessary to halt deterioration and always with the gentlest method
possible, such
as low
pressure water and soft natural bristle brushes.
DO NOT
SANDBLAST MASONRY UNDER ANY CIRCUMSTANCES.
It is
recommended to submit cleaning specifications to the Historical Commission for
review prior
to
commencement of the work.
Retain and
repair historic chimneys, even if an interior fireplace is to be removed,
because chimneys are
an important
architectural feature. The height and original or later historic pattern of
decorative
brickwork on
chimneys shall be maintained.
Do not
paint unpainted masonry unless historical evidence proves otherwise.
Repair or
replace deteriorated historic materials, where necessary, with new materials
that duplicate the
old as
closely as possible. Match carefully the
replacement bricks’ size, color, and composition to the
original.
Retain
whenever possible without the application of any surface treatment. Sealants, waterproofing, or
water repellent
coatings should be avoided at all cost unless they have been proven not to
block the masonry’s water
vapor
permeability, or to contribute to its long-term deterioration.
Incompatible
mortar can destroy historic masonry units by creating spalling. The spalling exposes
the softer
interior brick and allows for deterioration