Wednesday, May 9, 2012

02a - Humidity in a dwelling - how to avoid

We have already talked about some sources of humidity inside a dwelling:
  • the kitchen where water boils, the stew cooks, and water is always evaporating from pots and pans, 
  • our human bodies that constantly release water vapor, day and night, even when we are not perspiring,
  • bathrooms and toilets because hot and warm water does evaporate.
In addition we have to consider other sources of the water and humidity that enter our dwellings:
  • the roof that leaks and lets rainwater in. This water wets the interior of our dwellings and evaporates raising the humidity level,
  • the walls when poorly protected from the rain absorb humidity that will be gradually released into the inside of the building,
  • and the floor that absorbs the humidity from the surrounding soil releasing it into the dwelling.
The humidity in the soil penetrates the building floor making it wet. A wet floor will release its water contents by evaporation contributing to the discomfort of the building occupants. This is not a healthy situation since a wet floor harbors harmful microorganisms, pests, mold and various harmful insects.

For now we will concentrate on our dwelling floors. We will deal with the roof and the walls in another blog.
To control the humidity in the floor and so control the humidity levels inside our dwellings we can do a number of things:
  • build a foundation of stone or concrete blocks,
  • elevate the floor level above the level of the surrounding terrain,
  • cover the floor with some waterproof material.
A stone or concrete block foundation by itself will help but is not enough to keep the humidity and the water out. The water outside will infiltrate the soil and find its way under the foundation and into the building. Water will continue to infiltrate until its level inside the building is the same as the water level outside the building.

The solution to this situation is to raise the dwelling floor level above the outside terrain level. The humidity in the soil will still infiltrate under the building floor but will not completely infiltrate the raised floor leaving the inside of the building drier.

Even with all these precautions it is important not to build our dwellings in low lying land. Rain water will always find its way to the low lying spots in the landscape. We know this. But water that seeps into the soil will also do this. It will take longer but it will continue seeping into the building floor if the building is on low ground.
It does help to cover the building floor with a sheet of waterproof material, such as a continuous sheet of plastic, but it does not solve the problem of water infiltrations. And this solution, by itself, can prove to be expensive.
We can cover the floor of a building with a sheet of waterproof material but we should do this under the floor, as shown in the picture below. This sheet will protect the compacted soil or the paving material from the underground humidity making the inside much drier and healthier.

It is always beneficial to cover a compacted floor with some other flooring material that will make the interior of the dwelling more comfortable, healthier and cleaner, but first we need to solve the humidity infiltration problems.
If we install some flooring material without a continuous sheet of waterproof material below the floor it will always feel cold and uncomfortable in cold weather. On a cold floor we will see the formation of water condensation which will provide fertile ground for molds and other nuisances.
And we know this is not healthy for anyone.

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