Waterproof Airtight

VAPOR MOISTURE SOURCES

  

People and their daily rituals

  

Occupants produce through their every day activities high loads of moisture vapor and launch internal R.H. in big heights. We have talked about this subject in other entries. Hereunder we compile the main habits / activities that feed internal Relative Humidity.

 

1. High occupancy (fewer m2/occupant)

2. Bathing / showering

3. Cooking

4. Many plants

5. Clothes drying inside

6. Floor cleaning

7. Unvented appliances

8. Indoor swimming pools, jacuzzis, hot tubs, whirlpool baths and other similar installations imposed by modern lifestyle and prevailing social trends.

 

 

WATER VAPOR DIFFUSION

 

We have learned that water vapor moves through the building envelope proportionally to pressure differentials and resistance to vapor flow. Diffusion takes place both above and below ground and it's a much weaker mechanism than water vapor infiltration - exfiltration via convection.

 

  

EVAPORATION

 

Evaporation deserves a separate mention.

Evaporation happens when liquid moisture from wet surfaces is transformed in water vapor. This is the case when air vapor pressure is smaller than vapor pressure of the saturated air in the vicinity of the wet surface.

 

 

COMBUSTION

 

Unvented appliances can induce big moisture loads in the indoor environment.

 

 

CONVECTION

Because envelopes are never airtight massive loads of moisture can infiltrate or exfiltrate with the help of air movement.

We have talked about:

- wind effect and

- stack effect.

 

Water vapor transported via convection is manifold in relation the quantities transported through diffusion.

Air - carried vapor is responsible for serious interstitial condensations.

 

 

FEW WORDS ON CONDENSATION

  

Condensation phenomena take place when vapor-loaded air comes in contact with surfaces at temperature below dew-point.

Condensation is widely misdiagnosed as capillary absorption.

To broaden your knowledge on condensation, please read the "THE 4 PILLARS OF CONDENSATION PREVENTION".

 

Chris Strogilis

 

http://maconwaterproofing.blogspot.com

About the Author:

Civil engineer with postgraduate studies in MBA and Marketing

Article Source: ArticlesBase.com - Waterproofing Fundamentals:Moisture Sources In Buildings(2)