Ceiling Hunidity And Ceiling Ventilation Through The Roof Windows
Ventilation of the roof space
Trying to loose as little of warmth as possible, we often underestimate the necessity of ceiling ventilation. Mainly in the new, effectively insulated houses we can experience the vapor condensiation caused by the usual household activities (breathing, cooking, washing, etc...).
Why vapor condensates in the ceiling
Vapor condensation appears if the inner humidity of the ceiling is too high. The only way how to avoid the vapour condensation in the ceiling space is to moderate the temperature of the ceiling. And that means - the higher humidity the more effective ventilation is necessary.
The ceiling humidity
You cannot avoid ANY humidity.
Some portion of the water used in the household always gets to the air as a vapor.
Cleaning, ironing, washing dishes, drying clothes - these all are activities contributing to the quantity of water dissolved in the air. For example, one adult person can this way produce more than 5 litres of water daily.
The colder the air is the less water it contains (just compare the situation before and after your 14 old daughter showered, before - your bathroom is a nice dry place - after - it is a hot, wet hell with environs very similar to the rain forrest).
When cooling the hot air, the vaporised water dissolved in the air condensates (back to the fluid for again). You can see it the best on your
windows, as the windows usually have the coldest surface.
Celing ventilation through the roof windows
If your ceiling space is large and you often experience the vapor condensations, you should probably consider to install another roof windows in the upper part of the roof. Having pair of windows above each other offers you a fair chance of so called "chimney effect ventilation".
If you open both windows at the same time, the cold air is being sucked throug the lower window and the hot air is vented out through the upper window. Such ventilation is very effective and the time necessary to achieve the appropriate temperature is very short.
Venting recomendations
If you do not want to install new pair of roofing windows here is the handful of recommendations you should keep to improve the ceiling space ventilation.
- rather vent frequently, couple of shorter times daily, it is much more effective than just once daily but longer;
- the heater (heating element like e.g. radiator) should be installed right under the roof window;
- the window parapet must be placed so that it doesnīt prevent the air from circulating along the window.
