Condensation is the 'wet' surfaces you'll find in your property, normally on cold surfaces such as windows, walls and ceiling. This is caused by moisture-laden air floating around your property touching these cold surfaces, and being relieved of the moisture content in the process known as condensing.
Nobody wakes up one day and says, "I need extra ventilation", without good reason. Ventilation systems are usually ordered to solve a problem, or to prevent a problem before it occurs. We can fix condensation throughout a property, poor ventilation and removing bad smells in kitchens and w/cs - we can't fix water ingress, leaks or rising damp with ventilation alone.
