Page 356 - Construction Waterproofing Handbook

8.16 CHAPTER EIGHT

FIGURE 8.12 Cleaning completed before restoration work commencing. (Courtesy
of ProSoCo)

TUCK-POINTING

In most masonry structures, unless the masonry was handmade and is excessively porous,
any leakage is usually attributable to mortar joints. The water, moisture, or vapor that
passes through the masonry itself is usually repelled by dampproofing or flashing or weep
systems.
Through the aging process, all mortar joints eventually begin to deteriorate, caused by
a multitude of weathering factors. These include swelling of masonry, which when wetted
places pressure on mortar joints from all sides. This causes fractures and cracks along the
masonry and mortar junctures. Other factors contributing to mortar deterioration include
freeze–thaw cycling, thermal movement, and chemical deterioration from sulfites and
chlorides in atmospheric pollutants.
During life-cycling, weathering begins to allow significant amounts of water and mois-
ture through a masonry wall. Eventually this water may exceed the capabilities of existing
dampproofing systems, allowing water to penetrate interior areas. Entering water also
begins structural deterioration behind masonry facades.
If building maintenance inspections reveal that mortar deterioration is contributing to
excess water infiltration, tuck-pointing of mortar joints will be necessary. Tuck-pointing is
a restoration treatment used to restore the structural integrity of mortar joints. Tuck-point-
ing procedures include removing existing deteriorated mortar and replacing it with new
mortar (Table 8.5).
Inspections may reveal that only certain wall joints require tuck-pointing, or an entire
wall area may require complete tuck-pointing to restore the building envelope. If miscellaneous