Humidity

Humidity is when water is present in a structure or substance, regardless of its form (solid, liquid or gas). More generally, humidity refers to the amount of water in the air, i.e. the hygrometric level, also known as hygrometry.

What is humidity?

Humidity is an important factor in meteorology. Just like temperature and wind speed, measuring the amount of water vapour in the air is a key parameter in climate studies and weather forecasts.

However, when we talk about humidity most people think of humidity problems in the home. Although the presence of water in the air is normal, it shouldn't exceed a certain level indoors to avoid causing damage or health problems. The ideal domestic humidity rate is between 45% and 65%. A higher quantity of water vapour in the air is abnormal, creates a problem in the home and can have serious consequences.

The amount of water vapour the air can hold varies depending on the temperature. The lower the temperature is, the less humidity the air can contain. If the temperature falls, the water vapour can therefore no longer remain in a gaseous state. Saturation is when water condenses in the form of droplets deposited on the coldest surfaces. In the home, condensation usually forms on the least insulated windows, walls and doors.

There are also two separate concepts in humidity: absolute humidity and relative humidity. The first is used to measure the amount of water vapour in the air, while the second takes temperature variations into account and expresses the ratio between the water vapour in the air and the maximum amount possible according to the air temperature. It's therefore expressed as a percentage rather than in g/m³.

How do we measure humidity?

To measure humidity, either in meteorology or in a home, a measuring device called a hygrometer is used. There are several different types of hygrometer, some more sophisticated than others: mechanical hygrometers with a needle indicator, electronic hygrometers equipped with sensors, hygrometers connected to a weather station or the internet, etc.

All are designed to measure the humidity level, either outdoors to fine-tune weather forecasts or make adjustments to activities determined by weather conditions (farming, aeronautics, outdoor leisure activities, etc.) or indoors to measure the humidity in each room and identify the causes of excessive humidity in a home. Discover all our products

The consequences of humidity in the home

Excessive humidity can have serious consequences, both on the condition and longevity of a home and on its occupants' health.

• The problem of deterioration in a home

A humid building or room will quickly show signs of deterioration: damp stains, patches of moisture on the ceiling, floor or walls, peeling wallpaper, rings of condensation around the doors and windows, flaking paint, swollen or warped woodwork, rusted metal materials, etc. Although damp stains and odours are the most obvious consequences of excessive humidity, other symptoms that are less visible but just as critical are also cause for concern: the deterioration of woodwork and structural elements, the appearance of dry rot (which is part of the fungal family and attacks wood), saltpetre at the base of walls and various fungi and mould on the floor or walls that gradually spreads throughout the home. It therefore isn't just a health problem, it also poses a real risk to the longevity of the entire building.

• The health consequences of humidity

Excess water vapour in a home can also have serious consequences for the health of its occupants. Humidity causes respiratory illnesses such as asthma and can also exacerbate a joint or chronic issue, notably in frail individuals and children. The presence of mould and fungi in the home also promotes the development of allergies and respiratory illnesses.

How do you combat humidity in your home?

Fortunately there are many solutions available to treat excess humidity. First of all, an assessment needs to be carried out to determine the cause of the problem, then tailored solutions can be put in place.

• Ventilating the home

This is an essential step in gradually venting water vapour and preventing condensation. Open the windows regularly to vent your home, particularly in rooms with running water where steam is produced by cooking, washing machines, etc. Open the vents and install a good ventilation system. Depending on the extent of the condensation problems and whether extensive work can be carried out, several solutions are available. The most common are single-flow mechanical ventilation, which vents the air from humid rooms, and forced-air mechanical ventilation, which also raises the temperature of the incoming air.

• Good sealing

Humidity problems in a home can also be caused by a sealing problem. Check your bathroom (shower, sink, etc.) to eliminate any potential leaks. Have double-glazed windows installed to maintain a consistent temperature indoors and prevent condensation. Check that the building's roof is intact, have any cracks in the external walls repaired and replace defective doors for improved insulation.

• Devices for treating humidity problems

Various devices are available for dehumidifying a room. Some use a chemical process in which hydrophilic crystals absorb the excess water in the air in each room. Others work electronically, extracting water from the air by cooling the air. You can also make your own dehumidifier using coarse salt.

• Identifying the cause of the problem

Rather than masking the effects of humidity, the causes need to be identified. Sometimes it's enough to dry out a wall with a waterproof membrane or resin injection, or to drain the land around the home to resolve the problem. The problem of mould or dampness on the walls or floor is often caused by capillary rise rather than excess humidity inside the home itself.