Page 345 - Construction Waterproofing Handbook

REMEDIAL WATERPROOFING 8.5
prevalent nondestructive testing is water testing. In this analysis, water is applied by some
means to a structure to determine areas of infiltration. Water testing is also used to measure
moisture absorption rates of the various substrates that comprise a building envelope.
In conducting water tests, water is first applied at the base or bottom of areas being tested.
Succeeding applications of water then begin upward. This prevents water from running
down onto as-yet untested areas. Water should be applied in sufficient quantities and time
in one location to determine if an area is or is not contributing to leakage or absorption.
For more information on leak detection, refer to Chap. 13.
Once such a determination is made, testing moves to the next higher location. This test-
ing requires someone to remain inside to determine when water leakage begins to occur.
Water testing is limited in that it does not determine specific leakage causes or if leakage
is created by damaged envelope systems within a structure such as cavity wall flashing.
Sounding is an effective means of determining areas of disbonding on spalling masonry
materials. Such testing uses a rubber mallet to lightly tap substrates to discern differing
sounds. For example, hollow sounds usually signify spalled or disbonded areas.
Another sounding method uses chains on horizontal concrete, masonry, or tile surfaces.
This test is referred to as chain dragging. By pulling a short length of chain along a sub-
strate, testers listen for changes in sounds, carefully documenting hollow sounds. The extent
of those areas to be repaired is marked by painting or chalking an outline of their location.
Often, using a simple pocketknife to probe into substrates, without causing any perma-
nent damage, can substantially supplement the information learned from visual inspection.
A knife can be used to scrape along mortar joints to determine their condition. Should
excessive mortar be removed, it is an indication of an underlying soft porous and poor-
strength mortar, which will require attention during remedial repairs. Knives can also be
used for testing sealant joints by inserting the knife along joint sides to allow analysis of
sealants and to determine if they are properly bonded to a substrate.
Water absorption testing is similar to water testing, but only measured amounts of water
are applied to a specific, premeasured substrate area over a specific length of time. This test
can accurately determine absorption ratios of substrates. These results are compared to per-
meability ratios of similar substrates to determine if excessive absorption is occurring.
Modified laboratory testing at project sites can also be completed. This involves construct-
ing a test chamber over an appropriate envelope portion. Static pressure testing, as described
in Chap. 12, can then be completed. Such testing requires an experienced firm that has the
appropriate equipment to complete testing and the personnel to interpret test results.
Dynamic pressure testing of an envelope at project sites is also possible by using
portable equipment that can introduce high air and water pressures. This allows conditions
that simulate wind loading and severe rainfall to be applied against an envelope. Chapter 12
reviews job-site testing and mock-up laboratory testing in detail.
Other testing devices include moisture meters, which give accurate moisture content of
wood or masonry substrates, and x-ray equipment, which is used to locate and document
metal reinforcement. Reinforcement can also be somewhat less accurately located by metal
detectors and magnets.
More sophisticated equipment is available to determine existing moisture and its con-
tent in various substrates. This equipment includes infrared photographic equipment and
nuclear moisture tests completed by trained and licensed professionals.