About Your House
Measuring Humidity In Your Home
Do You Have a Humidity Problem?
Straight Facts About Humidity
Humidity is the amount of moisture or water vapour in the
air. You, your family, and your pets produce moisture when you
breathe or perspire. Even your indoor plants produce moisture.
We add water vapour to indoor air through routine household
activities: cooking,showering, bathing, doing laundry, and
dishwashing. And more moisture can enter your home from the
surrounding soil through a basement or crawlspace.
When Is Humidity a Problem?
We need humidity for our comfort and health. But too much
or too little humidity can produce a host of difficulties for
householders. Some of the problems are no more than
nuisances; others could be far more serious. Many are
familiar to Canadians, often occurring during the heating
season when it is very cold outside, our windows are closed,
and indoor air circulation and ventilation are reduced.
||Too much humidity
||Too little humidity |
||Condensation on windows
||Chapped skin and lips |
||Wet stains on walls and ceilings
||Scratchy nose and throat |
||Breathing problems |
||Static and sparks |
||Problems with electronic equipment |
||Damage to the house and contents
||Continuing discomfort |
||Damage to furniture and other items |
||Other health problems
Diagnosing the Humidity Problem
Instead of guessing whether or not you have a humidity
problem inside your house, why not find out for sure?
A small, inexpensive and easy-to-use instrument called a
hygrometer (sometimes referred to as a humidity sensor or a
relative humidity indicator) can measure the humidity level in
your house and confirm whether the house has too much or too
little humidity. Once you know for sure, you can decide
whether any action is required and, if so, what to do.
So You Want To Buy a
The two types of hygrometers that are most suitable for
household use are mechanical
hygrometers and electronic hygrometers. For most
households. either type will perform satisfactorily if
properly used and calibrated.
Hardware stores, department stores, building supply stores
and electronics stores often carry hygrometers. In fact,
hygrometers are usually sold wherever you would buy a room
thermometer. Hygrometers and room thermometers are often
combined into a single piece of equipment.
Using Your Hygrometer
Your hygrometer will show the relative humidity (RH) in
your house. Although the RH will not be exactly the same
throughout your home, one hygrometer per house is usually
sufficient. You should place it where the humidity symptoms
are most obvious, in the room that you are most concerned
about, or where your family spends the most lime. Because
hygrometers are small, they can be moved around in your house
from time to time.
Don't place your hygrometer near a radiator, a heat
register or a chimney, or in any other location where it could
be affected by direct heat.
Remember that a hygrometer does not produce instant
results. It may take up to two hours to provide a stable
reading in a new location or to adjust to sudden changes in
Humidity is normally measured as relative humidity (RH). RH
is percentage that indicates the amount of moisture in the air
relative to the maximum amount the air can hold at that
temperature. For instance, when air at a given temperature
contains all the water vapour it can hold at that temperature,
it has a RH of 100%. If the humidity exceeds 100%, moisture
will begin to condense from the air. If the air contains only
half the water it can hold at that temperature, the RH is
Warm air can hold more moisture than cool air, so that the
RH of a sample of air will change as the temperature changes,
even though the actual amount of moisture in the sample air
does not. For example, as a sample of air cools the RH
Humidity: How Much Is Too Much, Or Too Little?
Experts have developed rules of thumb to help homeowners
make decisions regarding humidity levels in their houses. The
limits should be used as guides only. Acceptable or
comfortable humidity levels will actually vary from season to
season, from house to house, and even between rooms in the
Recommended indoor RH: 30% to 50%
When it is below — 10oC outdoors, recommended
indoor RH: 30%
Humidity can be controlled. If the relative humidity in
your home is too high, you can reduce it; if it is too low,
you can increase it. This may require simple changes in your
family`s habits, such as remembering to open or close doors or
windows. Or you may need to install equipment, such as exhaust
fans in bathrooms or kitchens, to remove excess humidity.
Very low indoor RH levels in winter may be due to cold, dry
air leaking in from outside. Sealing up the house by
weatherstripping and caulking will improve humidity conditions
indoors, and may reduce your heating bills at the same time.
Humidifiers - both stand-alone appliances and devices attached
to your furnace - can be useful for increasing indoor RH
levels. But remember that humidifiers, if not installed, used
and maintained properly, can also be sources of excessive
moisture and mold in
The final analysis
Humidity levels in your home can be too high or too low. In
either case, problems can result.
A hygrometer can provide the information you need to
determine whether you have a humidity problem — but it must be
accurate to be useful.
If you have a humidity problem, it can usually be
Other useful Canada Mortgage and Housing Corporation
Air: Problem and Remedies