# Window condensation and your humidity reading > Understand a humidity reading, record recurring moisture and prepare a useful maintenance request without turning observations into a diagnosis. [Canonical article](https://makethisuseful.com/articles/window-condensation-and-humidity) By Make This Useful. Published 2026-09-08; updated 2026-09-08. Prepared with AI assistance. Worked examples are original fiction, not customer records or professional findings. ![Three separate pieces of a useful moisture record: the wet surface, the room reading and the unresolved question.](https://makethisuseful.com/articles/media/moisture-observation.svg) Original explanatory diagram. A room reading and a visible wet surface answer different questions; neither alone identifies a repair. You wipe water from the bedroom window. A meter on the dresser says 58%. Someone suggests replacing the windows; someone else says to buy a dehumidifier. Neither recommendation follows from those two observations alone. The useful first step is to separate the water you can see, the conditions you measured and the explanation you still need to check. This article helps homeowners and renters make that distinction and prepare a useful maintenance conversation. It covers ordinary observation and documentation, without asking you to open equipment or disturb building materials. The worked household below is fictional. Its readings illustrate how to keep a record; they are not targets for your home. ## What the number tells you Relative humidity describes moisture in air in relation to the temperature. A percentage without its temperature and location loses useful context. Dew point describes the temperature at which that air becomes saturated. These are related measurements, not interchangeable labels. The [National Weather Service explains the distinction](https://www.weather.gov/arx/why_dewpoint_vs_humidity). A room reading is also not a measurement of the glass, wall or pipe where you noticed water. For an ordinary note, record both temperature and relative humidity if your meter supplies them. Write “bedroom, dresser, 7:15 a.m., 19°C, 58% RH” rather than “the house is humid.” If the device only shows a percentage, record that limitation. You can still report a useful observation without inventing the missing temperature or buying another instrument before reporting a problem. The EPA's [household moisture guide](https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home) recommends keeping indoor relative humidity below 60%, ideally 30–50% where possible. It also recommends prompt attention to wet surfaces and water sources, drying water-damaged materials within 24–48 hours, and reporting moisture problems promptly to a landlord or manager. Those are general prevention guidelines. A reading within a suggested range does not establish that every surface is dry, and a high reading does not identify the cause of a particular damp patch. Significant water damage, contaminated water, suspected HVAC contamination or health concerns need appropriate professional attention; use the EPA's conditions rather than a humidity percentage to decide whether a situation is a simple observation task. ## Describe the water before naming its cause A useful description identifies which surface is wet and when you noticed it. “Water on the room-facing lower edge of the bedroom glass at 7:15 a.m.” gives a maintenance person something to locate. “Bad windows” begins with a conclusion. You may eventually find a window problem, but the second phrase throws away the observation needed to investigate it. Distinguish a photograph from a measurement. A photo can show the visible location, shape and extent of an observation at that moment. It does not tell you the moisture content inside the wall, prove that a dark mark is mold, or establish which repair will solve the problem. Keep a wider view for orientation and a closer view for the detail. Give them simple date-and-place labels so someone else can understand what each image depicts. If you cannot tell whether the moisture is on the near surface or elsewhere, write that uncertainty. Do not make the record more definite just to make the message sound polished. “I can see fogging but have not established which surface it is on” is more informative than an unsupported seal-failure diagnosis. Treat a new active leak, spreading water or an unsafe area as a reason to act through the appropriate maintenance or emergency channel, not as a reason to finish a multi-day diary first. Documentation supports getting help. It should never become a waiting period imposed on a problem that needs attention now. ## A small record that somebody can actually use Use one row for one observation. Keep the fields consistent enough that the next person can compare entries: - **Place and surface:** the bedroom window, lower room-facing glass; not simply “upstairs.” - **When:** a date and time, including whether this was before or after an ordinary activity. - **Reading:** the displayed temperature and humidity, their units and where the meter stood. - **What you saw:** beads, a wet sill, a stain or no visible water. Keep “not checked” distinct from “dry.” - **What changed:** something you actually did, with a time. Avoid filling in a fan runtime or window position from memory if you are unsure. - **Follow-up:** the next observation, the person contacted and what remains unresolved. The [blank observation sheet](https://makethisuseful.com/articles/downloads/moisture-observation.csv) uses these fields and opens in common spreadsheet tools. A paper notebook works too. You do not need a sensor history, a smart-home account or a technical vocabulary to supply a clear record. Keep observations from different rooms separate. A kitchen reading after cooking and a bedroom reading before breakfast can both be accurate without describing the same conditions. If you move the meter, record the move and follow its instructions about placement and settling. A change in the displayed number is not automatically a change in the underlying problem. ## Worked example: three entries, one honest request Imagine Rowan is reporting a recurring wet bedroom sill to the property manager. On Monday at 7:15 a.m., Rowan sees beads on the lower room-facing glass. The meter on the dresser reads 19°C and 58% RH. Rowan wipes the sill and takes an orientation photo and a detail photo. The record says the window was closed when checked; it does not claim how long it had been closed. At 1 p.m., the meter in the same place reads 21°C and 49% RH. Rowan notes no visible water on the glass or sill at that check. That is a different observation, not evidence that the earlier water never mattered. The time, conditions and visible state have all changed. Rowan does not write “fixed” because no repair has been established. On Tuesday at 7:10 a.m., beads are visible again. The displayed reading is 19°C and 57% RH. Rowan records the recurrence and sends the two morning photos with the observation sheet. Three entries are enough to explain the pattern Rowan has actually seen. They do not demonstrate a universal morning pattern, isolate a moisture source or establish whether the building needs different ventilation, an equipment adjustment or repair. Here is the resulting message: > I have found water on the inside lower glass and sill of the bedroom window on two mornings, Monday and Tuesday, around 7:15 a.m. I wiped the sill after the first check. At 1 p.m. Monday I saw no water, but it was visible again Tuesday morning. The attached photos identify the window and wet area. The attached readings were taken on the bedroom dresser, not at the glass. Could you inspect the recurring moisture and advise the appropriate next step? I have not established the cause. This is an original fictional communication example, not an inspection result. Notice what it preserves: location, recurrence, the action already taken, the limits of the readings and a concrete request. It does not need a dramatic diagnosis to make the problem worth attending to. ## Correct the record without losing the history Suppose Rowan later notices that Monday's first entry says 57% rather than the photographed 58%. The correction should change that number and leave the date, temperature and other observations intact. If a maintenance message has already gone out, send a brief correction: “Monday's first reading should be 58%, not 57%; the other details are unchanged.” Now suppose the first photo shows a different window than the description. That is a more consequential mismatch. Correct the place, label which photo belongs to it and check the message before resending. Do not merge records from two windows into one tidy story. A clear correction is more useful than silently replacing the entire account with a cleaner-looking version. The same principle applies when using an AI assistant. Ask it to organize supplied observations and preserve unknowns. Compare the result against your notes, especially room names, dates, units and statements about what was checked. A smooth paragraph can accidentally turn “not observed” into “not present,” or a requested inspection into a repair somebody supposedly completed. Those are changes in meaning, not merely style. ## Make the next visit easier Before a maintenance visit, identify the observations you want to discuss and the questions that remain. You might ask which checks are needed to distinguish possible sources, which observations would be useful afterward, and how to report a recurrence. Let the person responsible for the work establish the applicable method and access arrangements. Afterward, add what was actually explained or done, who supplied the information and the date. Keep recommendations separate from completed actions. “Manager said an inspection will be arranged” is different from “inspection completed.” “I was asked to observe the same window tomorrow morning” is different from a permanent maintenance instruction for every room. When you return to the record, begin with that last unresolved question. If somebody changes the explanation, keep the earlier observation available. A useful home record connects events without rewriting history to fit the latest answer. You can share a short selected copy with the maintenance person while keeping unrelated home details, access arrangements and personal messages elsewhere. ## Use your observations You now have a way to describe the issue, the limits of a humidity reading, a compact record and a worked maintenance request. Use the observation sheet independently, or bring your own note to Make This Useful and ask for an explanation or a clear message. Add the information relevant to your home; Rowan's fictional room and readings should never become your defaults. Review the result before relying on it. A helpful finish is a faithful account that the next person can act on, with the cause and repair still open until they are established. Save the reviewed version, retain the supporting observations and return when you have something new to add. ## Use this with your own information [Use my home observations](https://makethisuseful.com/start/understand-home-moisture) Read the task's example and sign in to continue with your own details. Personal setup is optional. [Download the blank observation sheet (CSV)](https://makethisuseful.com/articles/downloads/moisture-observation.csv) ## Sources and this edition Original explanation and fictional worked examples checked against the linked primary sources. No on-site inspection or professional certification. - [EPA: A Brief Guide to Mold, Moisture and Your Home](https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home): General humidity, prompt moisture response and escalation conditions; not a diagnosis of the fictional home. Checked 2026-09-08. - [National Weather Service: Dew Point vs. Humidity](https://www.weather.gov/arx/why_dewpoint_vs_humidity): Meaning of relative humidity and dew point. No building-specific repair conclusion. Checked 2026-09-08. First editorial edition: original observation method, fictional correction and maintenance message.