The preferred test for assessing floor moisture is the insulated hygrometer test procedure in BS 8203, Code of practice for installation of resilient floor coverings. This test effectively measures the moisture leaving the floor, rather than the moisture content of the floor. Signs of a concrete slab subject to excess moisture can include bubbling, blistering and spalling. Photo courtesy of Perkins Custom Coatings Waiting is important "Without a vapor barrier in place to protect the home from runoff from the roof or from irrigation, this water will easily pass through the slab on its way back to the atmosphere.

A common problem in unsealed CrawlSpaces high humidity is due to the

Multiple factors can influence the amount of moisture in a concrete slab, thus contributing to high RH levels for up to six months or more after concrete is poured. Sources of moisture in concrete: Wet curing; The initial amount of water in the concrete (from a high water/cement ratio); Concrete Moisture Levels Can Affect Flooring An acceptable moisture reading for concrete is usually 3.5 to 4.5 percent, which is considered dry for this material. Floor covering manufacturers will also list the allowable concrete moisture content on which their products can be installed.

Fig. 1: Free Water in Concrete 2. Moisture Rising from Below the Slab Concrete slab is exposed to a perpetual source of moisture rising from below provided that suitable moisture barrier or any other suitable technique is not installed to prevent moisture migration form below the slab. Fig. 2: Moisture Movement from below the Slab The test is conducted in three locations for every 1000 square feet of concrete slab. This allows you to determine the moisture level across the entire surface of the floor, rather than just one specific area. For each test site, a packet of very dry calcium hydroxide is poured into a container, which is then weighed.

How Does Moisture Move Through Concrete

Moisture Management Requires Accurate Moisture Readings Once the slab is poured, the excess moisture must leave the slab in order to strengthen the concrete bond. The slab must also dry to a specified level of moisture before flooring materials can be installed on top of it. Moisture-related damage to the flooring materials is possible. Moisture levels in a drying concrete slab tend to be higher at the bottom of the slab but will equilibrate (disperse evenly) through the slab once it has been sealed by a floor covering or other technique.

You can now understand the meaning of moisture content 5.5%, 15 g/m2/24 hours, and relative humidity 75% with these facts. Maximum Moisture Content Of Concrete This is a nominal value most product manufacturers specify when concrete is dry enough to allow their product to lay down on it. Acceptable moisture levels in concrete according to ASTM standard, when testing via ASTM F2170, the RH level of a concrete slab needs to be at or below 75% — unless the flooring system manufacturer provides alternate guidelines. Some flooring system manufacturers have products that can handle 95% RH or more. 2. How moisture gets into concrete

Remediating Moisture in Concrete is Not Complicated Concrete Decor

5 Things You Need to Know About Moisture in Concrete 1. Moisture Matters in Concrete 2. Moisture Moves in Concrete 3. Concrete Can't Be Rushed 4. Moisture Must Be Measured in Concrete 5. RH Testing: Have the Right Tool for the Job BONUS: Excess Moisture Can Be a Problem What do you do if the moisture level is too high in your concrete slab? Ed Wagner answers the question and gives some options in this brief video. For more i.

Excess moisture in the concrete slab can cause serious flooring problems, such as adhesive failure, discolored tile or grout, bubbles in sheet vinyl, and buckling of wood floors. An old slab under existing flooring can easily contain enough moisture to cause these issues for the new flooring. Older flooring systems often used products that were more moisture-resistant than many of the products used today, but also typically had a greater environmental impact. This means that an old concrete slab may be retaining moisture that was sealed by the older, more moisture-resistant flooring.

Understanding moisture related problems causes and the possible

There are a number of reasons why moisture-related flooring problems are so common today. First, we live in a fast-track world where construction schedules often do not provide sufficient time for concrete to dry naturally to a level acceptable for the installation of flooring or coating materials. Second, it is all too common for below-slab. ASTM-F-2170 is the standard used to measure moisture deep in a concrete slab through the application of thermo-hygrometers with in-situ probes. Thermo-hygrometers (sometimes called RH meters) are a special kind of moisture-testing device that can be used to monitor temperature and relative humidity conditions in a given area.