The implementation of a moisture control ventilation system into your home requires a review of the extent of dampness, and condensation issues, then consideration to the direction of airflow aligned to this moisture issues, as well as the number and type of units to make an effective long term solution. The factors that relate to these decisions are not apparent at the first impression
On visiting a property the first intuitive processes begin with the geographical location, if in a valley, exposed to the wind, subject to high water levels, as on a downward slope, the existence of local ponds, water storage rivers, sea, all aspects that hide the subterranean flow and hydraulic pressures of water.
The makeup of the ground has a significant impact, ie: chalk, clay, granite. The saturation, stability and moisture transference properties of these substances are different and do effects the impact of the level of water vapour pressure that your home is subjected to. In the case of granite, Radon needs to be considered as well as moisture control.
An account is taken around the degree your property has been incarcerated with water impermeable membranes, these suffocate your homes ability to breath, denying its ability to maintain a natural equilibrium of moisture with the ambient external environment.
Many instruments exist that give the appearance of providing a reading that can be recorded and a figure given that would create the impression of having a handle on these factors, giving the belief that the operator knows what this really means and therefore providing the most informed answers, and at the same time giving the customer the impression, that an expert is at hand and the investment in the opinion is valid.
What do Measurements really mean? See my list of the many variables
- Construction material, its permeability with water, its age, integrity of its built form.
- Chemical interaction with adjacent material (ie: corroded nail in concrete, the effects of the expansion and decomposition of the structural integrity, soot in chimney and salts produced).
- Ground water
- Encasement with internal or external artificial vapour barriers.
- Historic build ie: change from timber to concrete type floors,
- New with old build
- Adjacent properties having been changed/sealed causing hydraulic shifts in water pressures movement
- Passive ventilation system
- Existing and new leaks
- Occupational effect on water content of the air and surroundings
- Capillary action
- Thermal affects (ie:Heating, Weather, Geology)
Available instrumentation for measurements of the above include
%RH, Absolute Humidity, Temperature surface internal & external, Vapour Pressure, Air Pressure differentials, Moisture Permeability, Altitude, Chemical analysis, Volume/dimension, Air density, Thermal properties. Air flow.
Having considered all of the above as a science technician with over 30 years experience of moisture control with air movement, it has become apparent that in the majority of cases instrumentation while giving customer satisfaction, and confidence was in reality of, no or little value for the ventilation solution derived. Some exceptions arise that require a quantitative analysis, such as intrusive water content analysis, however, these fall out of the scope of the need, for a final ventilation solution.
It is the case that an experienced intelligent surveyor being aware of all of the above, will take visual observations, sense the air, and the immediate environment, gather relevant information knowledge from the person experiencing the issues, and form a ventilation solution that will act dynamically and automatically to the known variables