Vibration, measured properly.

Higher than most people expect. BS 7385-2 puts the threshold for cosmetic damage (hairline plaster cracks, not structural harm) at a peak particle velocity of around 15 mm/s for residential buildings at low frequencies, rising to 50 mm/s at higher frequencies, and 50 mm/s for sturdier industrial buildings. For comparison, people can feel vibration from around 0.3 mm/s. Vibration that feels alarming is usually well below any damage threshold. Measurement settles it either way.

Rarely, but it's the right question to ask before piling or demolition starts next door. Perception begins around 0.3 mm/s; cosmetic damage typically needs around fifty times that. Monitoring during the works records the actual levels at your property, which protects both sides: the contractor gets evidence of compliance, and you get evidence if levels were exceeded.

BS 6472-1's measure of human exposure to vibration in buildings, accumulated over a full day or night rather than a single moment, so frequent events count for more than rare ones. The standard gives ranges for the probability of adverse comment in homes. We measure, calculate day and night VDVs, and state plainly which range you're in and what, if anything, needs to change.

Very likely, if homes are proposed close to a surface railway, tram line or tunnel. Councils routinely condition one. We measure at the site, ideally where the buildings will stand, assess against BS 6472-1, and where levels warrant it, specify isolation in buildable terms so the condition can be discharged.

Every project is a fixed fee agreed up front, so we don't publish a price list. Send a postcode and a brief description of what's moving (or what's proposed) and we'll come straight back with a figure. No day rates, no surprises.

It depends on the source. A complaint investigation can sometimes be resolved in a single attended visit; rail sites need long enough to capture the full service pattern, typically at least 24 hours. Either way, the report lands within five working days of the survey.