This contact point of the different air temperatures is known as the initial condensing surface.
The initial condensing surface is what controls the particular room’s moisture behaviour as it limits the existence of absolute humidity amounts. Since windows are a room’s coldest surface, condensation is highest in this area
Levels of relative humidity ought to be maintained at below 70F which is 60%. To maintain these, you may need to do some mechanical dehumidification and structural changes. Remember that although there may be high levels of relative humidity in a given area, saturation levels will be at the initial condensation surfaces.
- Are there some sections in the house that are unheated such as the closet or basement?
- Is there sufficient ventilation in the kitchen and bathrooms through fans and windows?
- How often is there a presence of condensation in the building?
- Is the relative humidity increased because of the heater being turned down?
- Is there adequate insulation in the house?
- Does the attic have adequate ventilation? Condensation tends to occur in attics hence the need careful observation for moisture.
The problems that can be caused by mildew and molds can be adverse in both heating and cooling climates. One common example is in rooms where air from conditioners blows against an exterior wall’s interior surface. Diffuser issues, diffuser location, and poor duct design, creates a cold area at the interior walls when outdoor air hits the cooled interior surface cavity side, thus causing a mold problem to grow in the wall cavity. This is a common condition in rooms that have low maintenance interior decorating such as vinyl paper which are notorious for trapping moisture between the gypsum board and interior finish. Mold can also grow rapidly on cold spots and interior as well as exterior finishes.
Common areas that surface moisture can be found in elevated levels:
- Areas where there is direct contact between furniture and exterior walls which limits airflow
- Kitchen and bathroom ceilings where the ventilation is unused or is improper
- Closets that are located next to the exterior walls
- Exterior walls and more so, corners
- Roof sheathing ensures that the attic has sufficient ventilation
- Single pane or windows that are old style (condensation is higher with metal frame windows )
- Wall cavities that are close to an A/C unit.