Vibration felt by people does not have to mean a risk of structural damage, and the absence of complaints does not prove structural safety. These two objectives require different measurement points, metrics, evaluation periods and reference documents. Before installing the equipment, write down separately: "we assess the impact on the structure" and "we assess user comfort".
In short
- Damage concerns the structural response; comfort concerns human exposure and the response to vibration in an occupied room.
- ISO 2631-2:2026 addresses comfort and annoyance in buildings, but it does not assess the likelihood of structural damage or the impact on health.
- A point on the foundation, a point on the slab and a sensor near the source are not interchangeable. Each describes a different stage of vibration transfer.
- One PPV or RMS value without direction, band, time and standard does not answer both questions.
- A platform can organise waveforms, spectra, bands and alarms, but it does not issue an automatic statement of compliance with a standard.
When residents report floor vibration, an investor often asks one question: "Did we exceed the standard?" That sentence hides at least two problems. The first is whether the vibration can damage the structure. The second is whether the conditions are annoying for people. If the scope of work does not separate these objectives, you can perform a correct measurement and still fail to get the answer needed for the decision.
That distinction matters commercially and contractually. A scope that is too narrow ends in a second measurement, a dispute over interpretation, or a promise that the report cannot support. A scope that is too broad raises cost without a clear acceptance criterion. First, you need to establish who the result is for and what it is meant to support.
Practical requirements for the structural track are developed in the guide on vibration monitoring of buildings according to PN-B-02170.
Two objectives that must not be combined under one threshold
Assessment of the impact of vibration on a structure is an analysis of the object's response with respect to the possibility of damage or another undesirable technical outcome. Relevant factors include the type and condition of the building, the source, frequency, amplitude, duration, direction and measurement location. ISO 4866 describes the principles of measurement and data processing for assessing the impact of vibration on structures, but it does not give one limit for every object.
Assessment of vibration comfort is an analysis of a building user's exposure to vibration in the place and at the time of occupation. ISO 2631-2:2026 covers comfort and annoyance related to whole-body vibration in buildings in the 1-80 Hz range. The document defines, among other things, the measurement direction and location, as well as the Wm frequency weighting. It does not assess the likelihood of structural damage or health effects.
| Question | Structural damage | User comfort |
|---|---|---|
| subject of assessment | technical response of the building | human exposure and annoyance |
| typical location | foundation, structural member, top storey - depending on the method | floor or a point representative of the user |
| context | type, condition and dynamics of the object | time of day, activity, room, exposure time |
| result | quantity required by the relevant document | weighted value and exposure character |
| supporting evidence | damage survey, documentation, visual inspection | event log, complaints, way of use |
| decision | change of works, diagnostics, protection | reduce annoyance, organise works, further assessment |
This table does not set thresholds. It shows why one sensor installed "where it was convenient" and one number in a message do not close both topics.
Why a complaint is not proof of damage
A person can feel motion that remains far below the level associated with structural damage. The reaction depends not only on amplitude. Frequency, duration, repetition, time of day, type of activity and the resident's expectations all matter. ISO 2631-2:2026 notes that annoyance is influenced by vibration characteristics and non-vibration factors. A single number does not describe the whole experience.
The reverse reasoning is just as risky. The absence of complaints does not mean that structural measurement is unnecessary. The building may be empty, the event may occur at night in an unused part, or the response of a significant element may not be clearly felt. Direct observations from people are contextual information, not a substitute for instruments and analysis.
A crack also does not determine the cause. It may have existed before the works started, or it may have arisen due to shrinkage, temperature, settlement or another action. BS 7385-2 recommends combining measurement, recording and analysis with a precise damage register. That is why a pre-works condition survey has a different role from vibration measurement: it allows you to compare condition, but it does not measure the excitation itself.
The worst simplification is: "the residents feel it, so the building is cracking." Such a statement needlessly escalates conflict. Equally weak is the statement: "there is no damage risk, so the complaint is unfounded." You can stay within the structural criterion and still cause real annoyance. Two assessment tracks let you say honestly what is known and what a given measurement does not resolve.
Measurement location is part of the answer
The vibration path usually runs from the source through the ground or structural element to the foundation, then through the load-bearing system to the slabs and the place where the person is present. The response can be amplified in a specific band. A result near the machine describes the source, not automatically the resident's exposure. A result on the foundation does not have to match the motion of a lightweight slab on an upper storey.
Before installation, record the following for each point:
- purpose: structure, comfort or source diagnostics;
- sensor element and mounting method;
- axis orientation in the building's physical coordinate system;
- required bandwidth and input quantity;
- hours and mode of room use;
- sources that need to be distinguished;
- assessment document and its edition.
Direction also matters. ISO 2631-2:2026 requires the measurement direction to be specified, and the standard for structural assessment may indicate other locations and components. A sensor rotated after servicing, without updating the description, may still produce a plausible-looking chart, but it may assign vertical response to a horizontal axis.
In practice, it is worth creating a point map with three labels: "source", "transmission" and "receiver". This helps the engineer see whether the measurement answers a question about structural behaviour or about human perception. This simple classification reduces the risk of buying equipment that collects a lot of data in the wrong places. Separate acceptance is required for sensor mounting, axis orientation and cable routing, because a correct point on the drawing does not guarantee good coupling to the structure.
The metric, time and band must follow the objective
PPV, RMS, FFT spectra and third-octave results are not interchangeable. PPV describes the peak velocity according to the adopted definition. RMS depends on the time window and bandwidth. FFT shows frequency components, and third-octave bands group the response into bands with constant relative width. The detailed differences are described in the guide on PPV, RMS, FFT and third-octave bands. The parameters of the recording itself must then be checked separately; the guide on sampling, trigger and pre-trigger selection serves that purpose.
For comfort, exposure time and frequency weighting can be important. A short impulse and long, repetitive vibration may have a similar peak, but a different perception. For structures, frequency, short-term or continuous character, type and condition of the building, and the response point can matter. You must not transfer a damage threshold into a comfort report just because the unit looks similar.
Every reported value should include seven elements: physical quantity, unit, point, direction, time, band and assessment method. If one is missing, the result is hard to compare and easy to over-interpret.
| Missing information | Interpretation risk | Acceptance test |
|---|---|---|
| measurement point | comparing the source with the recipient's criterion | photo and plan with location |
| axis direction | using the wrong component | orientation check after installation |
| RMS window | diluting an impulse or overstating exposure | recalculation on a test signal |
| filter or weighting | a different result from the same waveform | profile and algorithm version record |
| event time | no link to the works or complaint | synchronisation with the source log |
| standard and edition | comparison with another method | document cited in the report |
Procedure for two tracks from the assignment to the decision
First, separate the questions in the specification. The structural track may read: "assess the impact of vibration from the works on the specified building according to the approved method". The comfort track: "assess user exposure in selected rooms and periods". Each track gets its own points, metrics, criteria and result recipient.
Next, establish a common context. Record the source operating time, event type, work location and user reports. Synchronisation does not prove causality, but it helps distinguish a heavy vehicle pass-by from equipment operation, a door slam from a ground impulse, and a real event from a blow to the sensor.
When the result has contractual or dispute relevance, the article on monitoring data as evidence develops the required scope of records.
Illustrative example. Suppose a residential building stands next to piling works. A sensor on the foundation records short events, and a point on the slab of the third storey shows a response in a distinct band. Residents report annoyance in the evening. You do not infer damage from that. You assess the structure according to its criterion, and comfort according to the relevant method, time and location. The shared time stamp, however, lets you link the complaints to the work cycle and plan a change in the schedule.
After analysis, issue two conclusions. The first answers only the technical question about the structure, with the limitations of the points and the document. The second describes exposure and annoyance. In the summary, you can present them side by side, but not merge them into a single "good/bad" colour. A result prepared this way is clearer for the engineer, the contractor and the resident.
Checklist before starting the measurement
- [ ] The structural purpose and the comfort purpose have been recorded separately.
- [ ] For each purpose, the relevant document and edition have been identified.
- [ ] The points have been assigned to the source, transmission path or receiver.
- [ ] Axis orientation and mounting method are documented by photo.
- [ ] Bandwidth, sampling and amplitude range follow from both objectives.
- [ ] PPV, RMS, weighting, third-octave bands and windows used in the report have been defined.
- [ ] The logger time is synchronised with the works log.
- [ ] A method for recording complaints without implying a diagnosis has been agreed.
- [ ] A condition survey has been carried out if the evidence plan requires it.
- [ ] The report separates measurement fact, interpretation and decision.
- [ ] The person authorised to approve the conclusion has been identified.
- [ ] Limitations and areas not covered by the measurement are explicit.
What it looks like in Inclify
Inclify stores full vibration events and shows the time waveform, FFT spectrum and 21 third-octave bands from 1 Hz to 100 Hz. For the third-octave profile, RMS and MAX values are available, as well as an alarm comparing the active bands against the reference envelope. These data help separate an impulse from a band response and arrange events on separate dashboards.
For one project, you can prepare an operational view for the works, a structural view and a view intended for annoyance analysis. WARNING and ALARM alerts with hysteresis, and e-mail and SMS notifications, support action according to previously approved criteria. The platform retains the history of states and acknowledgements.
Inclify does not issue an automatic declaration of compliance with ISO 2631-2, ISO 4866, DIN 4150-3, BS 7385-2 or Polish standards. A third-octave chart alone does not certify the entire measurement chain. The selection of sensor, point, calibration, metric, weighting and threshold remains part of the project and the specialist's assessment. The platform provides data and alarm rules; it does not replace engineering judgement.
Dynamic signal summaries can be exported to XLSX, and the chart image can be kept in documentation prepared outside the platform.
Limitations: what one measurement will not resolve
Point-based recording does not describe the whole building. A lightweight slab may respond differently from a load-bearing wall, and a user in the adjacent room may experience another level. If the objective is a dispute or a decision about changing the construction method, the layout must cover realistic transmission paths and recipients.
A measurement does not automatically determine the cause of an existing crack. Visual inspection, condition documentation, chronology and assessment of other actions are needed. Likewise, a complaint is not a "user error". It is evidence of perceived annoyance, which must be described with the proper method, even when the structural track does not indicate an exceedance.
Standards have a scope of application and require the full text. ISO 2631-2:2026 does not give universal acceptable levels and does not assess health or damage. ISO 4866 does not cover every special structure. The selection of the national criterion, the status of the standard and the contractual requirements is made by a competent person for the specific case.
FAQ
Do felt vibrations mean that the building is being damaged?
No. The threshold for perception and annoyance can be much lower than the level associated with the possibility of structural damage. The result depends on frequency, duration, location and the building's characteristics. The complaint should be taken seriously, but assessed on a separate track. A damage conclusion requires a structural method and technical context.
Does not exceeding the damage criterion close a resident complaint?
No. Such a result answers only the question covered by the structural criterion. Annoyance may occur at lower levels and depends on exposure, time of day and the way the room is used. The report should clearly state whether comfort was measured, where and by what method. Otherwise, you must not conclude that there was no annoyance.
Can one sensor be used for both assessments?
Sometimes the same recorder can serve several points or provide auxiliary data, but a single location rarely represents the foundation and the human exposure point at the same time. The measurement design decides. If one point is to serve two purposes, you need to show why its location, band, directions and chain satisfy the requirements of both methods.
Which standard applies to human comfort in buildings?
ISO 2631-2:2026 applies to comfort and annoyance related to whole-body vibration in buildings in the 1-80 Hz range. In Poland, PN-B-02171 may also be relevant. The correct document depends on the objective, the contract and the project requirements. The current edition and scope of application should be confirmed by a specialist before measurement.
Can a comfort alarm stop works automatically?
An alarm can quickly notify the team of an exceedance of the approved level, but the action must follow an agreed procedure. That procedure sets out data verification, responsibility and the conditions for limiting or stopping the works. The platform itself should not independently interpret the standard and make decisions on safety or contractual liability.
What should be retained when there is a vibration dispute?
Keep calibrated waveforms, time, location and axis orientation, recording parameters, the analysis profile version, results from both tracks, the works log, complaints and condition documentation. In the report, separate the data from the interpretation. This package makes independent re-analysis easier and is stronger than a screenshot with a single value.
Sources and further reading
- ISO 2631-2:2026 - Vibration in buildings, 1 Hz to 80 Hz - official scope for assessing comfort and annoyance for building users.
- ISO 4866:2010 - Vibration of fixed structures - principles of measurement and data processing for assessing the impact of vibration on structures.
- DIN 4150-3:2016-12 - Effects on structures - official description of the method for assessing the impact of vibration on structures designed mainly for static loads.
- BS 7385-2:1993 - Guide to damage levels from groundborne vibration - measurement, recording and analysis of vibration transmitted through the ground.
- PKN - standards search - information on current editions of PN-B-02170 and PN-B-02171.
What next
Before the next measurement, take the current scope of work and mark separately the structural objective, the comfort objective, the points, the metrics and the assessment documents. If these fields are shared or empty, correct the scope before installing the equipment. Talk to the Inclify team if you want to prepare a two-track pilot on one building and see what data will really be needed for the decision.