How to detect moisture under flooring?

Author: Jesus Oberbrunner  |  Last update: Sunday, September 28, 2025

Moisture testing before installation of a floor covering These tests can be carried out with Tramex concrete moisture meters, RH probes, moisture content probes and surface thermometers. These are available in specifically designed concrete moisture test kits.

How do you check for moisture under flooring?

This standard calls for the use of a thermo-hygrometer with in-situ probes to measure the relative humidity conditions deep in the slab—an approach that is far more reliable than taking surface-level moisture measurements with a flooring moisture meter.

How do I know if I have water damage under my floor?

How to Spot Water Damage in Your Floors
  1. Discoloration. One of the earliest signs of water damage is discoloration. ...
  2. Warping or Buckling. ...
  3. Soft Spots or Weak Areas. ...
  4. Musty Odors. ...
  5. Peeling, Cracking, or Lifting. ...
  6. High Humidity Levels. ...
  7. Heavy Rainfall and Flooding Risks. ...
  8. Clay-Heavy Soil.

How do I know if there is moisture under my tile floor?

Here are some signs that water has made its way into and under your tile floors:
  1. Discoloration. The iron in natural stone can oxidize (rust), turning the stone yellow, brown, or red. ...
  2. Efflorescence. ...
  3. Spalling, pitting, and flaking. ...
  4. Mold and mildew. ...
  5. Tiles are lifting.

How do I get rid of moisture under my floor?

The most common and effective way to do this is by using a dehumidifier in tandem with fans to help draw out the air humidity and excess water quickly. Other common ways to dry out your concrete floor include, but are not limited to: Using a wet vacuum to suck up excess moisture.

What is a moisture meter?

Why is my floor wet but no leak?

Excess Water Coming in From Doors and Windows

If it's not the pipes or the foundation, the water might be coming in through your home's windows and doors. Improperly sealed windows can leak on a rainy day, and the water can drain down the wall and into the floors and subfloors.

What soaks up moisture under house?

To remove the standing water from your home, you need a device that will soak up the water and put it elsewhere. This is what a sump pump does. There are two types: pedestal sump pumps and submersible sump pumps.

How can you tell if mold is behind tile?

Discoloration, like dark spots or stains around grout lines or on the tiles themselves, may indicate mold growth beneath the surface. Loose or damaged tiles from moisture buildup are a common symptom of hidden mold. Recurring problems with bathroom condensation or dampness.

Can a moisture meter detect water under tile?

If you suspect water damage under your shower tiles, one way to test for it is by using a moisture metre or a thermal imaging camera. A moisture metre is a handy tool that can detect the presence of moisture in various materials, including tiles and grout.

How to tell if subfloor is damaged under tile?

9 Common Signs of Subfloor Damage
  1. Your floor is uneven or sunken-in. ...
  2. Your floorboards squeak — loudly. ...
  3. The room smells musty. ...
  4. Your floors shift or bounce when you walk on them. ...
  5. Your toilet is rocking or loose. ...
  6. Your flooring has cracked. ...
  7. Your hardwood floor is cupping. ...
  8. Your linoleum floor is bubbling up.

How to detect a water leak under the floor?

  1. Watch For Sudden Water Bill Increases. ...
  2. Inspect For Wet or Damaged Flooring. ...
  3. Follow Moldy or Musty Smells To The Source. ...
  4. Take Visible Mold Seriously. ...
  5. Monitor Unusual Noises. ...
  6. Check for Damaged Concrete. ...
  7. Link Potential Outdoor Issues. ...
  8. Know What to Do After Detecting a Water Leak Under Your Concrete Floor.

Will homeowners insurance cover water damage to floors?

Homeowners insurance generally covers water damage that's sudden and accidental. For example, if a pipe bursts or a washing machine overflows and damages your floor, you may be covered. But if the water comes from flooding, standard homeowners insurance typically won't cover it.

Does wet subfloor need to be replaced?

In most cases, damaged subflooring doesn't need to be replaced. However, in the event of extensive water damage from flooding or extended periods of exposure to moisture, damaged sections may need to be removed to avoid mold and ensure structural integrity.

Can you test for mold under flooring?

The only way to know for sure is to carefully pull up the floorboards or tiles where you suspect mold to be growing underneath. You can also use a mold test kit or have your home inspected by a professional, depending on your budget and the severity of mold.

How do I know if there is water under my floor?

If you see water coming up through the seams, or hear a squishing sound, you can know for sure that water is underneath your floor and it needs to be removed.

How do you fix damp under the floor?

When faced with damp in concrete floors, there are two options available:
  1. Dig up the old concrete floor, install a new damp proof membrane and lap up edges before replacing the concrete slab.
  2. Fully isolate the dampness in the floor using a surface Damp Proof Membrane (DPM)

How do home inspectors check for moisture?

An inspector can use a moisture meter to locate moisture that would not otherwise be apparent. Here are a few ways that inspectors may find moisture meters useful: A moisture meter can be used to determine whether a material is moist enough to allow mold to grow.

How do you test for floor moisture?

A hygrometer box is sealed to the floor with putty or butyl tape and left in situ for 3 to 7 days. It will entrap air and moisture, and is left long enough for the moisture to reach a point of equilibrium.

Can mold grow under tile flooring?

Mold loves dark, damp environments, like the underside of your tiles. Once water gets underneath them, mold can start to grow in as little as 24 to 48 hours. If you spot green or black spots around the grout line or notice a new musty smell, it's time to bring in a mold removal specialist.

How do you check for moisture behind tile?

Pinless Moisture Meters (AKA: Non-Invasive Moisture Meters)

Non-penetrating moisture meters don't tell you actual moisture content -- they help confirm the presence of moisture within a substance or area. Use in areas such as behind ceramic tile or vinyl floors where there are no visual signs of water.

What are symptoms of black mold exposure?

The most common symptoms of black mold exposure include:
  • Sneezing.
  • Coughing.
  • Nasal congestion.
  • Postnasal drip.
  • Red eyes.

How do I get rid of moisture under my house?

Proper drainage is another great way to keep moisture away from underneath your home. Drainage could include cleaning out your gutters and downspouts, adding more downspouts, grading the yard away from your home, or installing a sump pump to remove any standing water.

What will draw moisture out?

Open windows and doors to help speed up the drying process. Use fans to move air around the damp walls. Also use dehumidifiers, which can help remove moisture from the air and walls. Professionals use tools like moisture meters, infrared imaging devices, dehumidifiers and heavy-duty fans.

Does DampRid really help?

Does DampRid work? Yes. CHOICE household products expert Chris Barnes says, "We put a DampRid container in a sealed test chamber about the size of a closet with 80% humidity and a fan for air movement. Within three days, DampRid reduced humidity to 43% and collected almost half a cup of water."

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