Hygrometer Readings at Home: What to Measure and What It Means

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What you are seeing

Mould on a bedroom wall, glass that streams every morning, or a musty smell with no obvious cause. You suspect damp air but cannot tell whether it is a habit, a vent or a building fault. The Centre for Sustainable Energy says a hygrometer can show what makes humidity rise, such as drying laundry or cooking, and what brings it down, such as opening a window or running an extractor fan. That turns a hunch into a pattern.

Rule these out first, cheapest first

1. Step 1, free: decide which room you are testing. GOV.UK guidance describes condensation settling on the colder parts of a building, for example window frames, corners and low points on walls behind sofas or wardrobes. Test where the trouble shows, not in the hallway, and write the room and the date at the top of a sheet of paper.
2. Step 2, low cost: buy a basic digital hygrometer. The Centre for Sustainable Energy says they can cost as little as 8 pounds. Cheap units can differ from each other, so if you own two, put them side by side for an hour and see how far apart they sit before trusting either.
3. Step 3, free: log it for a week. Note the reading on waking, mid-afternoon, at bedtime and 30 minutes after a shower or cooking. BRE says recording humidity and temperature in a series of rooms and outside, at half-hourly intervals, is the most effective way of diagnosing damp. A paper log is a rough home version of that, and it needs no app.
4. Step 4, free: read the pattern, not one number. A spike after cooking that falls back within the hour suggests your ventilation is coping. A reading above 60 per cent for most of the day matches the mould-risk threshold the Centre for Sustainable Energy gives. A reading that climbs overnight in a shut bedroom points to people breathing, which the Centre lists among the everyday sources of moisture.
5. Step 5, low cost: change one thing, then re-read. Open a window for a few minutes, run the bathroom fan, close the kitchen door while cooking, move a wardrobe off an outside wall. The Centre for Sustainable Energy suggests all of these, and a second week of readings shows which one actually moved the figure in your home.
6. Step 6, trades: if the air reads normal but the wall is wet, call someone. Energy Saving Trust advice says leaks, rain getting in and rising damp usually need a professional, and recommends quotes from three TrustMark-certified firms. A hygrometer reads the air only. The RICS consumer guide separately warns against a surveyor who relies only on a damp meter, because damp meters can give high readings from materials other than moisture.

The Ashford factor

We have not found published humidity readings for Ashford homes, so we are not going to quote any. The 40 to 60 per cent range above is national guidance, and your own log is the local evidence that counts. Homes in Kennington, Willesborough and out towards Wye vary a lot by age, heating and how many people live in them, which is why a week of your own numbers beats a rule of thumb.

When a dehumidifier is not the answer

If the log shows normal air but a wall stays wet, or the damp patch follows the rain, the water is coming from a leak, a gutter, the roof or the ground, and a dehumidifier will not fix that. Mould already growing must be cleaned off whatever the reading says. If you rent, a portable unit is more realistic than a loft-mounted system, and you should report damp to your landlord. A high reading is also not proof of a fault in a home that is simply cold; see the winter heating habits guide.

Where Dryzen fits

If your log shows steady high readings that habits and fans have not shifted, a Dryzen system is the last rung, not the first. It is a loft-mounted dehumidifier and fresh air system with insulated ductwork to the central area or stairway. Each unit covers up to 150 square metres, extracts about 12 litres a day and costs about 20 pounds a year to run. It includes a smart app showing temperature and humidity (it needs 2.4GHz Wi-Fi and an internet connection), with a default target of about 50 to 55 per cent that sits inside the 40 to 60 range and can be adjusted between 40 and 70. It helps stop the conditions mould and dust mites need. It suits owner-occupied homes with a loft and is not suitable for rentals unless the landlord authorises the changes. Your log makes the free survey conversation much more useful.

Quick questions

What humidity level is too high at home?

The Centre for Sustainable Energy recommends keeping relative humidity between 40 and 60 per cent and says there is a risk of mould growth when it goes above 60 per cent. One brief spike after a shower is normal; a reading that stays high is the signal.

Where should I put a hygrometer?

No source we checked sets a placement rule. Our suggestion is the room with the problem, away from the bathroom door, kettle and radiator, at about the height you sit or sleep. GOV.UK guidance names cold window frames, corners and the low points behind sofas and wardrobes as typical condensation sites.

Can a hygrometer tell me if I have rising damp?

No. It measures moisture in the air, not in the wall. BRE says damp is often misdiagnosed and that the type must be correctly identified before treatment works. A steady high air reading is a reason to investigate, not a diagnosis.

Sources: Centre for Sustainable Energy: Condensation, damp and mould; 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; RICS: Damp and mould consumer guide

Last reviewed 2026-10-22. General guidance only; this is not a survey of your home.