Humidity is a measurement of the water content in the air. It’s usually measured in percentages or grams per cubic metre.

If humidity levels are too low or too high, you may notice adverse health conditions and issues in the home such as damp patches or wooden floor panels shrinking.

The humidity inside a typical home will vary throughout the year for varying reasons, including air temperature and ventilation and the lifestyle of the occupants.

How to Get an Accurate Reading in the Home

Humidity Detectors are very accurate at telling the user how much moisture is in come in all shapes, sizes and prices.

Professional units cost hundreds of pounds and provide the user with extremely accurate results.

There’s plenty of choice for the homeowner with so-called “desktop” monitors that cost upwards of £10.

You should keep a spreadsheet detailing all the readings in each room, also note the temperature as the amount of moisture the air can hold depends on the room temperature.

This humidity detector has a five-star rating and over 4000 reviews on Amazon

What is an Ideal or Normal Humidity Level?

The ideal relative humidity level for a UK home will depend on the outside temperature.

In general, around 50-55% is ideal for a typical summer and between 45-50% during a mild winter.

Issues With Low Humidity

Low humidity levels in the home can cause dry skin, itchy eyes, a sore throat and can even irritate the nasal passage.

Timber such as wood flooring and those in some cabinets or shelves may shrink and crack.

Rubber door seals, gaskets and any other materials that hold moisture may show signs of shrinkage.

Issues With High Humidity

High humidity levels are a common problem in homes that have been over-insulated.

Homeowners and tenants have reported respiratory illnesses, asthma and clammy skin.

In the home you can expect damp walls, timber cabinets and floorboards swelling, mould, and general moisture and condensation issues.

Bugs such as dust mites will thrive in a damp environment, as will woodworm and similar wood-boring creatures.

Short-Term Solution to Reduce Humidity Levels

A popular short-term solution is to run a dehumidifier. This will extract the moisture from the air and place it in a container so you can dispose of it.

They require electricity and are often noisy, hence why they’re not a suitable long-term solution.

Other options include any steps you can take to vent the property, even opening windows or leaving them slightly ajar, if it’s safe to do so.

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Long-Term Solutions to Permanently Reduce Humidity

There are two causes of high humidity levels, the first is excessive moisture creation in the home, the second is a lack of adequate ventilation.

The first step is to try and reduce the amount of moisture entering the home.

Common causes are:

• Drying clothes on radiators
• Leaking rainwater gutters and blocked pipes.
• Leaking freshwater pipes.
• Blocked sewers.
• Leaky heating pipes.
• Leaking roofs.
• Poorly constructed groundworks where rainwater flows towards and not away from the home.

Once you’ve ruled out damp penetration, the next step is to improve the ventilation in the home.

The worse culprits are usually the kitchen from cooking and boiling, the bathroom from showering and bathing, and the bedroom from perspiration.

Kitchens should have extractor fans fitted, ideally a very powerful one if the room doesn’t have a window.

Bathrooms without windows are a major cause of high moisture and humidity levels. The extractor fan should have a humidity sensor inside so it can activate and switch off automatically.

Did you know that the average human will lose over half a litre of moisture through perspiration each night? Without adequate ventilation in the bedroom, that moisture may condensate on cold windows, ceilings and walls.

Common solutions include:

Air bricks placed adjacent to floating/suspended floors (if your home has them):

Window trickle vents work very well, especially in the bedroom:

Passive input vents are a favourite of mine as they’re cheap to run and work silently and efficiently to filter out bad, foul and moist air:

Passive Input vent (PIV) system. Read reviews on Amazon

Further Reading

Condensation damp is explained in detail over at the Heritage House website.

Our own guide to reducing condensation is a great read too.

Explore how to reduce humidity in the home naturally.

This guide was written by Danny Woodley and was last updated in April 2022.

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