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 Figure 4-7.
Repainting.
(Source: Harley J. McKee, Introduction to Early American
Masonry, Copyright 1973, National Trust for Historic
Preservation)
1.
Old weathered brick or stone often has worn, rounded edges.
Feather edges of mortar break off, taking with them particles
of brick.
2.
Recessed joints look better and are less susceptible to
damage.
3.
When soft bricks are pointed with hard cement mortar, the
hard mortar remains but the bricks disintegrate.
CAUSES OF MASONRY DECAY
Major Causes of Masonry Decay. A certain amount of water is
natural and necessary in all bricks and stones. However,
when the moisture content is too high, soluble salts within
the masonry may crystallize and cause damage. Where do the
salts come from? Often they are brought up from the soil by
rising damp, which is caused by water being wicked up into
the masonry from wet ground and foundations. The damage
caused by rising damp may reach one to two feet above the
ground. In much the same way, chemicals used to melt snow
from walks and drives near a building can leach into the
walls and crystallize. In cold climates, excessive moisture
within the masonry alternately freezes (expands) and thaws
(contracts), with similar harmful results. Under flood
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