Condensation can appear in any building, but understanding why it forms takes more than a quick glance at a damp surface. Inspectors rely on accurate readings to understand what the air and materials are doing, and a condensation survey brings that information into focus.When humidity rises or temperatures shift, moisture settles in ways that reveal where a structure may be under stress. A clear survey helps separate surface dampness from signs that point to a deeper issue.
This piece looks at how a condensation survey works and how hygrometers and damp meters support the process during an inspection.
What Does Condensation Look Like Inside a Building?
In small doses, condensation build-up inside a building is very common. In fact, most of us see it every day inside our homes – e.g. the mirror in your bathroom after a hot shower.
Excessive condensation inside a building is indicative of a much bigger moisture issue, as it can be the result of several underlying causes.
What Causes Condensation Inside a Building?
Condensation forms when warm, moist air inside the building comes into contact with an area or surface that's cooler and/or has lower ventilation, such as windows or walls. In addition to this, high levels of indoor humidity can make it difficult for any moisture inside a building to evaporate properly. This means that excess moisture may remain in the air or condense onto surfaces, both of which are problematic for long-term building health.
What are Condensation Signs?
When condensation is a bigger issue – one that requires investigation and remediation – it presents itself inside a building in several ways. It goes beyond noticing condensation on walls and windows. You’ll also note condensation build-up causing:
- Water stains or discoloration on ceilings, walls, or floors
- Mold or mildew growth
- Musty or unpleasant odors
- Peeling paint or wallpaper
- Increased humidity levels
What Problems Does Condensation Cause?
In many respects, the signs of condensation are also problems caused by the excessive indoor moisture.
Still, persistent condensation can lead to other more serious issues. Left untreated, condensation over time can cause:
- Wood rot
- Structural damage
- Weakened walls
- Corrosion on metal components
Beyond structural issues, excess indoor humidity can also create an environment conducive to pests – e.g. termites and rodents – which will thrive in areas with plenty of moisture. Additionally, high levels of indoor humidity may make it difficult for occupants to breathe properly and sleep soundly.
| Condensation issues are especially noticeable – and problematic – during the colder months of the year. As many building owners turn toward supplemental heating sources – such as propane, butane, and gas heaters – in order to stay warm, the moisture produced by these sources often exacerbates any existing condensation problems. This is particularly true for propane heaters, as water is a byproduct of the gas as it's burned. |
Measuring Condensation With Hygrometers and Damp Meters
The first step in resolving condensation problems is identifying the exact source and extent of the issue. To do this, a digital hygrometer and a dual-function damp meter are both tools that can be used to measure condensation in buildings.
A digital hygrometer is an instrument that measures relative humidity (RH) – i.e. the amount of water vapor in the air compared to what would be considered saturated – as well as temperature readings. These devices are typically small and portable, making them ideal for taking multiple measurements throughout a building quickly.
Dual-function damp meters are designed to not only quantify moisture content in a material but also qualify its presence. These devices feature the functionality of both a pin-type and pinless (non-invasive) damp meter.
Let's look at how both devices are used to detect condensation in a building.
Using a Hygrometer to Detect Condensation
As condensation is driven by many ambient elements in an environment, a hygrometer – particularly one that is outfitted with an infrared thermometer – is ideal for locating areas with a high potential for moisture.
When using a hygrometer to determine condensation presence inside a space:
- Complete an initial visual inspection, Check for signs of condensation, such as water droplets on windows or walls, damp spots on ceilings or floors, or a musty odor.
- Place the hygrometer in the area where you suspect there may be condensation. Be sure to keep it away from windows, doors, or other areas where it may be exposed to direct sunlight or drafts.
- Allow the hygrometer to acclimate to the room temperature for at least 15-20 minutes and make sure the room stays undisturbed.
- Take an RH reading on the hygrometer. FYI: If the RH is above 60%, this may indicate that there is excess moisture in the air, which could lead to condensation.
- Using the hygrometer's non-contact infrared thermometer, take temperature measurements of any surfaces that have had condensation issues in the past.
With both RH readings, ambient temperature, and surface temperature readings, your hygrometer will be able to calculate whether a surface is above or below the dew point – or the point that condensation will form.
Understanding Temperature in Hygrometer Readings
As hygrometers measure a space's RH – something that's directly impacted by temperature – a sudden change in the environment's temperature has an immediate impact on the device's ability to work properly.
For instance, if a window is opened and the outside environment is hotter than inside the building, the warm air flooding the space can make humidity increase and condensation form on cooler surfaces.
That's why step #3 is critical to completing a successful condensation survey with a hygrometer. Even a slight disturbance in a space's temperature can have a big impact on readings.
Further Reading: Hygrometers & Temperature: Effects & Best Practices
Detecting Condensation With a Dual-Function Damp Meter
To an extent, using a dual-function meter to detect condensation requires a mindset of stepping into taking the readings sideways. While the device is not designed to detect condensation, both its functions do allow the user to still find areas of concern for the surface-level moisture.
Pin Mode Readings
Pin-type meters determine actual moisture content in a material by measuring electrical resistance between its probes. Taking accurate measurements requires that the pins simply make contact with the surface of the material being tested. In other words, there's no need to jam the probes into the material.
With a Protimeter damp meter, when its pins make contact with surface-level dampness (such as condensation), the meter will give a much higher damp reading. That's because condensation provides a path of least resistance to the electricity traveling between the meter's probes.
Using a pin meter to test for condensation does require taking multiple readings of the same material to ensure that you're not simply measuring high moisture content because of a different issue.
Pinless Mode Readings
In non-invasive or non-penetrating mode, detecting condensation presence happens in a different way.
Protimeter pinless meters are used to assess the average moisture within their depth of measurement. Note that some other meters will give you the highest reading found first, which is not helpful for condensation detection if the wall is only wet on the surface or completely wet from water ingress. Though they do not provide an exact moisture content reading like a pin-type meter, they confirm whether moisture is present.
When condensation is present, Protimeter pinless mode readings are impacted nominally, seeing only a slight increase in the average dampness within its depth of measurement.
How Pin and Pinless Readings Support a Condensation Survey
With a high pin mode reading combined with a low pinless mode reading, a user can extrapolate that the dampness detected is indeed surface level.
However, high readings in both pin and pinless modes indicate moisture has saturated the material being tested and the detected dampness is part of another issue, such as a leak.
How Do Inspectors Decide Between a Hygrometer and a Damp Meter?
Though both hygrometers and dual-function damp meters play different roles in measuring condensation in a building, a hygrometer should be your first choice.
Put simply, its functionality is best suited for pinpointing which areas throughout the building may be affected by condensation.
Still, there's no reason to leave a dual-function meter out of an inspection for condensation. Even though it helps identify condensation and areas of concern in a different manner, it's helpful in confirming areas of moisture, as well as ruling out other issues.
Just like in a standard building-wide dampness inspection – for which a damp meter is the go-to tool – having both devices on-hand only helps a surveyor do a more thorough job.
The bottom line: Though both devices are useful tools in assessing indoor humidity issues, having both on hand ensures that you'll have all your bases covered when investigating condensation problems inside a building.
Correctly Identifying Condensation in a Building
Compared to other major dampness issues (a burst pipe, for example) condensation is a relatively easy problem to remedy.
In the majority of cases, stopping condensation means:
- Installing appropriate ventilation in a space
- Increasing heat or addressing poor insulation for consistent temperatures
- Using a dehumidifier
However, condensation can be misdiagnosed as another common dampness issue: rising damp. When misidentified, condensation remediation efforts are for naught.
Like condensation, rising damp appears as moisture on surfaces – primarily walls and foundation floors – inside a building. However, the key distinction between rising damp vs. condensation is that the former only reaches a height of 1 meter from the floor in a space. In addition, rising damp often leaves salt efflorescence in its wake.
FAQ: Condensation SurveysInspectors often raise a few common questions when working through a condensation survey, and the answers below help clarify what readings and conditions can reveal during an inspection. Q: What RH or surface-temperature thresholds indicate a true condensation risk?A: RH around 60 percent or higher signals that moisture in the air is building. When a surface sits only a few degrees above the dew point, the conditions make condensation more likely, especially when airflow or heating is inconsistent. A useful survey compares RH and surface temperature together. If a surface repeatedly approaches dew-point conditions while the rest of the room seems stable, that area is at risk of ongoing condensation. Q: How long should conditions stabilize before measurements are considered reliable?A: A hygrometer typically needs fifteen to twenty minutes to adjust, though the room may need longer if windows were opened or heat sources were recently used. The goal is for the space to settle so readings no longer jump. Steady values over several minutes show that RH and temperature have leveled out. Once the numbers hold, the readings can inform the survey with confidence. Q: How do I confirm whether condensation is the primary issue or a symptom of another moisture source?A: Surface moisture tends to show through high pin readings paired with lower pinless readings. When both readings climb, moisture may be coming from deeper inside the structure. If dampness appears with staining, deterioration, or salts, or if it returns in the same spot regardless of weather, it may point to water ingress or another underlying issue that a condensation survey alone cannot resolve. |
Bringing a Condensation Survey Together
A condensation survey gives inspectors a clearer view of how moisture is moving through a building. With steady readings and enough time for conditions to settle, the patterns behind surface dampness become easier to understand.
Hygrometers and damp meters each contribute to that work. Used together, they help inspectors separate a simple surface issue from something that points to deeper moisture concerns.
A Reliable Meter Belongs in Every Toolkit
This article was originally published in April of 2023 and was recently updated to reflect current industry trends.