Your floor could look bone dry and still have enough moisture to cause problems once you cover it. Which is why. “How do you know how much moisture is in your concrete floor?” Can become a question you want answered before you buy any materials. Spread your adhesive or install that epoxy coating.
Test for moisture in concrete using a known quantitative method. Whether that is in-situ relative humidity testing to ASTM F2170 or calcium chloride testing to ASTM F1869 (when applicable). A moisture meter can be helpful to find problem areas but should not always be looked at as the answer.
Why Looking at Your Floor Isn’t Going To Give You The Answer
Concrete doesn’t need to look wet to have moisture in it.
Concrete dries from the top down. With airflow over your slab, temperature and your HVAC, you can have a very dry-looking top and moisture still in your slab. When you install a flooring system that has low permeability, like vinyl plank or an epoxy coating. You can run into big issues with moisture.
Excessive slab moisture can lead to flooring failure by debonding of the coating or deteriorating your finished floor.
At Custom Concrete Prep & Polish we believe testing your floor for moisture should be part of your floor prep process. We offer moisture mitigation and many other concrete flooring services in the Denver Area. Including grinding, shot blasting, leveling floors and applying epoxy coatings and polyaspartic.
Your floor telling you it looks dry is not going to give you the full picture.
What is In-Situ Relative Humidity Testing?
In-situ relative humidity testing to ASTM F2170 is one of many tests you can perform on your concrete slab before flooring installation.
Holes will be drilled in the slab and special probes are inserted to take a relative humidity reading inside of the concrete. Not only at the surface. This lets you know what is going on inside your slab. According to ASTM, internal RH testing is a recognized method before installing moisture-sensitive floor coverings and coatings.
When moisture is under a floor covering it can redistribute. So you may have a dry top that you feel confident will dry out your floor. An internal RH test can help you know if your slab is ready to install your flooring system.
Custom Concrete Prep & Polish also uses RH testing when performing moisture mitigation. We like to know what is going on under our floors before we apply coatings or sealers to concrete.
What Does a Calcium Chloride Test Tell You?
A calcium chloride test can also give you information about moisture in your concrete.
When performed to ASTM F1869 you are measuring the Moisture Vapor Emission Rate (MVER) that is leaving your bare concrete floor. This is measured in lbs of moisture leaving your slab over a 1,000 sq ft area in 24 hours.
Many flooring and adhesive companies will have max MVER levels that are safe to install over. Which is why this test has become so popular in the flooring industry.
Keep in mind.
This test is only telling you that moisture was leaving your floor during the time you performed the test. ASTM states that your results may not reflect conditions at the time of installation.
So be sure to know what your flooring manufacturer recommends for moisture testing. Some will require you to test for RH and others MVER. Or both.
Don’t pick a test method and pick your floor afterwards.
Know what your floor requires before you purchase it.
Can You Just Use a Moisture Meter?
Can you just use a moisture meter?
You can use a moisture meter. But they aren’t going to give you the best information about your slab.
Moisture meters are great to find areas that are reading differently than the rest of your floor. They can allow you to know where to focus on more.
Quick.
Convenient.
Just not something you should rely on if a coating or flooring manufacturer is requiring you to test your floor.
Custom Concrete Prep & Polish thinks that using a moisture meter is good to have when checking for surface moisture. But using RH or Calcium Chloride testing is going to give you more information about your slab.
It’s like asking where to dig on your slab. Not if you should dig at all.
Should You Tape Plastic to Your Concrete?
Taping plastic to your concrete is something that has been used for many years to see if your concrete has moisture.
By taping plastic to your floor you can see if you have any capillary moisture coming up from your slab. ASTM D4263 is used to indicate if you have moisture on your floor prior to coating.
If you have condensation forming under the plastic or your floor turns a darker color. You have moisture on your floor.
But what if you don’t have moisture?
You now know your floor doesn’t have moisture coming up but you don’t know what your RH or MVER levels are. So again you don’t know if your slab is dry enough to install that epoxy or adhesive you are wanting to use.
It’s good information. Just not the best information.
My Concrete is Years Old, Do I Need to Test?
You may think that because your concrete has been there for many years it is dry. There is always a chance your concrete still has moisture. Not only from the water that was added to create the concrete. But ground moisture can also travel up through your slab if you have an on-grade or below grade slab. If there isn’t a proper vapor retarder under your slab.
Conditions in your building can also affect your slab. Changes in HVAC or drainage. Water, ground water and humidity can all affect your floor.
Which is why Custom Concrete Prep & Polish recommends that even if your floor is many years old you can still have moisture issues.
It has been there for years.
How Dry Does My Floor Need to Be?
Again this depends on what you are installing on top of your slab.
Each coating, adhesive, and flooring system has different moisture levels that are safe to install over. Always test your floor and compare it to the manufacturer’s install instructions.
Don’t go off of other rules of thumbs from different coatings.
Make sure your floor meets your floor specifications.
What if my floor tests too high for moisture? It doesn’t always mean your floor can’t be covered.
There may be times that you just need to allow your floor to dry out more.
Depending on your slab and building conditions it may take longer than what you want. Some floors will need a moisture mitigation system installed to lower the amount of moisture that can leave your slab.
Custom Concrete Prep & Polish offers moisture mitigation that can lower the amount of moisture that can leave your concrete. We use products such as VaporSolve 100 LP which is a 100% solid that can be applied to high moisture concrete floors.
Again you need to make sure your floor is prepped correctly. Applying a moisture mitigation system over an improper slab will cause more problems for you down the road. Grinding, shot blasting, cleaning your slab and getting a proper CSP can all play a role in moisture mitigation.
Do you test your floor before or after preparing it?
Again this depends on what test method and flooring system you are working with. Always follow your test method and flooring manufactures instructions. You want to know that the floor your flooring contractor is going to be working with is free of any old coatings or materials. That may not be giving you true information about your slab.
Maybe you need to remove that flooring first to get a true picture of what your slab looks like.
So remember to test your floor before covering it.
How do you know how much moisture is in your concrete floor? Test your floor for moisture before covering it. You can test for RH to ASTM F2170 which will give you a reading from within your slab. You can also perform a calcium chloride test to ASTM F1869. Both of these can be beneficial when trying to determine if your slab is ready to be covered. Moisture meters and taping plastic to your floor can be helpful. But if your floor or coating requires testing make sure to do that.
Custom Concrete Prep & Polish can test your floors for moisture. We also offer moisture mitigation, concrete grinding, shot blasting, levelling, and epoxy coatings and polyaspartic. Contact us today for all your commercial, retail, industrial and more concrete needs around Denver and the Mountain West.
Contact Custom Concrete Prep & Polish today and we can help you with your next project. Better to know before you cover your floor.
