Vibration velocities (peak particle velocities, PPV's) and their frequencies are the measure by which the relative vibration damage potential is judged (see Vibration Standards for additional information on this point). One cannot easily know vibration velocities just by feel. These must be determined by vibration monitoring studies, carefully done and properly interpreted.
However, in the majority of construction vibration damage situations, vibration monitoring is either not done at all, done only selectively and incompletely after a damage report, done so poorly that it has limited scientific value, or is not fully produced to the homeowner by the construction contractor, even when under court order. Thus, it is difficult for many people to know if felt vibrations are capable of causing damage until after the damage appears, either immediately for particularly high velocity vibrations or later for somewhat lower velocity ones. The delayed appearance of damage may contribute to additional damage from subsequent vibration events.
Separating the Injurious from the Irritating
Since people are more sensitive to vibration perception than homes are to vibration damage, it is important to understand how one might begin to make a distinction between likely non-damaging vibrations and those which might have damage potential. This can be important when no vibration monitoring studies are done or are done without real-time feedback to the homeowner or construction crew.
Following are a few tips on how to assess vibrations with respect to damage potential. These tips are neither quantitative nor definitive, since vibrations from a given source type can vary substantially in velocity. They should not be used for quantitative purposes. However, within their limitations, I hope they will help give some rough guidance and aid to homeowners who must decide what actions they might take after the vibrations occur.
Vibrations which are often "safe"
Vibrations which may indicate a need for follow-up measures
There are many other possible vibration situations not discussed here, as these are only some of the most commonly found. A vibration meeting any of these guidelines is neither proof of damage potential, nor its absence. In the end, such criteria should be used to help people know when further monitoring may be justified or necessary.
Following Up on Troubling Vibrations
In the typical construction vibration situation where there is no vibration monitoring to establish actual vibration velocities, these tips can, perhaps, help set your mind at ease - or give you some encouragement to document and investigate further. Those types of vibrations noted as concerns should trigger further investigation and, perhaps, immediate documentation of the condition of your home.
You should investigate whether vibration monitoring is being done on the nearby project. You may also want to supplement any done for the contractor with your own monitoring, if the vibration is sufficiently concerning or has already produced damage. Having your own vibration information, either seismograph vibration velocities from a retained vibration monitoring firm or acceleration data from a smart phone or tablet computer's built-in sensors, can be extremely valuable in the all-too-common situation in which the contractor entirely denies (usually without evidence) producing damaging vibrations.
A clear bottle or other container filled with water, as at left, can be a useful means of demonstrating the presence of vibrations. However, such a visualization method cannot be used to measure, or estimate, the velocity of vibrations numerically nor can it be used to draw any meaningful conclusions about such numbers.
The PDF and Pro versions of the CVDG have an Appendix B - Warnings Signs which addresses vibration concerns from the standpoint of visible effects on the home. Its content is complementary to this section of the CVDG and should probably be read by those who have read this information.
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