Hygrometer Guide: How to Measure Humidity at Home

Rung 1: Get a reading (free to cheap)

A hygrometer is an inexpensive digital gauge, often sold with a thermometer. Some are stand-alone and some connect to a phone. Whichever you choose, the habit matters more than the price.

• Pick the right spot. A shelf at about head height in the middle of the room, away from radiators, windows, steam and direct sun.
• Use two. Put one in the room with the problem, such as a bedroom with condensation or mould, and one in a room that feels fine. Cheap units can disagree with each other, so put them side by side for an hour first to see how far apart they read.
• Write it down. Note the reading at the same times each day, for example waking, midday and bedtime, for a week or more. Some units store highs and lows for you.

Rung 2: Read the pattern (free)

The pattern is the diagnosis. BRE describes logging relative humidity and temperature at regular intervals as the most effective way of diagnosing damp, because it shows what is actually happening over time and not just on the day someone looks.

• A spike after showering or cooking that falls within a few hours: normal, and a sign extraction and ventilation are doing their job.
• Highest in the morning in a bedroom: overnight breathing in a closed room. Try a trickle vent open or the door ajar.
• High all day in every room: the home is holding too much moisture overall. Look at laundry, ventilation and heating habits.
• High in one room only, with a cold wall: a cold surface or a leak. The Energy Saving Trust notes that damp is more likely in places colder than the rest of the house, and where air cannot circulate, such as behind furniture.

GOV.UK guidance on damp and mould lists consistently high relative humidity, assessed with a moisture meter or environmental monitors, among the signs to look for. It also says that smart sensors can be a useful aid to monitor temperature, humidity and indoor air quality. They should not be used to blame occupants, and in a rented home they should only be installed with the tenant's consent and understanding.

Rung 3: Act on what you see (cheap to moderate)

If humidity spikes and stays up after cooking or bathing, check the fans actually vent outside and run them for longer. If bedrooms are the worst, give the room more air. If readings stay high in every room, cut the moisture you add: cover pans, dry laundry outdoors when it is dry and warm, and wipe condensation off windows. Our healthy humidity guide explains the range to aim for. If one wall stays damp even when readings elsewhere are fine, rule out a leak, because a hygrometer measures air, not water coming through a wall.

Rung 4: When mechanical help makes sense

If you have fixed leaks, sorted extraction and cut the moisture you create, and the readings still sit high in an owner-occupied home with a loft, a loft-mounted dehumidifier such as Dryzen is one option. It is not suitable for rentals unless the landlord authorises changes, and it will not help with a leak or rising damp. A Dryzen system has temperature and humidity monitoring through its smart app, which needs 2.4GHz Wi-Fi and an internet connection, and works to a default target of about 50 to 55 percent humidity. The Gold Pack membership (£199 per year) includes remote humidity monitoring and a yearly onsite system check: we alert you if there are any issues with your home or the dehumidifier.

Mistakes that make readings useless

• Putting the hygrometer on a windowsill or radiator shelf, where it reads local conditions and not the room.
• Judging by one reading taken just after a shower.
• Trusting a single cheap unit without checking it against a second.
• Treating a moisture meter reading on a wall as proof of rising damp. BRE warns that moisture meters can lead to misdiagnosis.
• Reading humidity in a room with an open window in winter and thinking the problem is solved.

In Chatham and the Medway Towns

The pattern differs by street. Solid-wall terraces near the Historic Dockyard have cold external walls, so a hygrometer in a bedroom on an outside wall is the one to watch. Newer estate houses further out, towards Walderslade and Lordswood, are often warmer but more airtight, so readings tend to depend more on how well the home is ventilated. See our pages for Gillingham and Lordswood for how each plays out.

Questions we are asked

Related guides

• The healthy humidity level for your home
• Condensation on Windows: What It Is Telling You
• Bathroom and Kitchen Extraction That Actually Works
• Getting a Damp Diagnosis Right Before You Pay for Work

Local help

• Damp, mould and condensation help in Gillingham
• Damp, mould and condensation help in Lordswood
• Damp, mould and condensation help in Rochester

Sources: BRE: Diagnosing the causes of dampness in buildings; GOV.UK: Understanding and addressing the health risks of damp and mould in the home; Energy Saving Trust: How to get rid of damp.