Dampness is harmful before you can realise it is there. It is important to note that materials do not become visibly damp, and do not feel damp to the touch until they are quite dangerously damp.
Wood, for example, does not feel damp below 30% moisture content (i.e., around 97 or 98% relative humidity), although rot will start to develop at 20% moisture content.
Thus dampness is hazardous long before it can be detected by the unaided senses. This is why it is so essential to use a moisture meter for surveying for damp and making judgements about its severity.
At Surveying Cymru we are passionate and dedicated to understanding what it is that may be causing the issues that you are experiencing in your home and our surveyors are all fully qualified and experienced and will utilise all of the tools at their disposal to identify and classify what problems are causing the water ingress that is causing the dampness.