What is the in-place strength of existing unreinforced brick masonry? These eight tests can be used to determine the in-place strengths of such structures. SURVEYING RELATIVE STRENGTH The first tests should quickly and inexpensively locate regions of high and low strengths. Knowing these regions, the engineer can determine how many in-place strength tests are needed. These four tests are: hammer test; rebound hammer test; the probe-penetration test; and the ultrasonic pulse velocity test. MEASURING IN-PLACE STRENGTH After finding relative strengths, the investigator has a better idea of where to directly measure in-place strength using the core, shove, flat jack, or interior bond wrench tests. Each test requires removing masonry units or mortar from the wall. This makes some wall repair necessary.