Restoration logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Restoration logo
  • NEWS
  • PRODUCTS
    • New Products & Technologies
    • Submit Your Product
    • Interactive Product Spotlights
  • EDUCATION
    • KnowHow.
    • Podcasts
    • Trade Shows & Expos
    • Training & Certification
    • Webinars
    • Whitepapers
  • TOPICS
    • Water Damage
    • Fire & Smoke Damage
    • Mold
    • Contamination
    • Odor
    • Contents
    • Architecture
    • Catastrophe
    • Cleaning
  • BUSINESS
    • Managing Your Business
    • Insurance/Legal Matters
  • BUYER'S GUIDE
  • VIDEOS
    • Ask Annissa
    • Ask the Expert
    • Ironclad Marketing Minute
    • TradeTalks
    • Video Channel
  • INFOCENTER
    • Mold and Mycotoxins
  • THE EXPERIENCE
    • Conference & Exhibition
    • Convention & Trade Show
    • R&R Special Issue
  • EMAG
    • eMagazine
    • Archive Issues
    • Contact
    • Advertise
  • SIGN UP
Water Damage RestorationInsurance/Legal Matters in Restoration

When is Concrete Really Dry?

By Chuck Boutall
Water-Damage-Restoration.jpg
March 1, 2012

The real answer? Never. As with most materials, concrete retains a certain amount of water when in equilibrium with the build environment.

 

The real answer? Never.

As with most materials, concrete retains a certain amount of water when in equilibrium with the build environment. However, concrete is a particularly wet material. Using ASTM #2170, the equilibrium relative humidity (ERH) test, most flooring manufacturer guidelines require the concrete maximum moisture to be between 70 and 75% ERH before placement of the floor will be warranted. Furthermore, 70 to 75% ERH is usually about 0.70 to 0.75 water activity. That makes concrete one of the wettest of our “dry” building materials.

As with any drying project, make sure you have identified the source of the water that has made the concrete too wet to apply flooring. Except for prolonged flooding, most water losses only cover the concrete with for as little as a few hours to as long as a day. This is seldom enough time for the water to penetrate the surface and saturate the concrete. Therefore, in most water losses, the moisture on the surface of the slab will usually evaporate in the time it takes to dry the structure - especially if the structure is timber framed.

If the slab shows that it is still too wet to place flooring after the rest of the building is brought back to its normal equilibrium, there is usually an underlying reason for the excess moisture. Reasons may include an insufficient moisture barrier under the slab, a water pipe or hydronic heating leak, garden sprinklers spraying on the building, etc. You must determine the original source of the water in order to prevent the problem from reoccurring.

Now, if the concrete has been tested, and it has been confirmed that it is too wet for the flooring by either moisture-vapor emission rates (MVER) or the ERH ASTM standards - and the source has been corrected - drying must be performed. Determine the goal specified by the flooring manufacturer and allow ample time for the project. Concrete takes weeks - not days - to dry. That’s the way it is – concrete absorbs water slowly and releases it even more slowly. Most flooring material standards are either 3 to 5-lbs of evaporation per 1000 square feet (MVER) or 70 to 75% (ERH).

Drying is best achieved with air dew points below 30ºF and constant low velocity airflow. Temperature is up for discussion. Several friends of mine like to heat the slab anywhere from 85 to 95ºF, raising the internal vapor pressure. Others point out that if you do not heat the slab thoroughly, you may drive moisture deeper into the concrete (note: cooler areas deeper in the concrete have lower vapor pressure compared to the hotter surface attracting some of the excess moisture) and then when the heated portion of the slab cools back down to 70 to 75ºF, the moisture “bounces” back to the surface, necessitating further drying and time loss. The main problem here is it is difficult to test concrete while you are drying at elevated temperatures.

 

Testing must be done according to ASTM standards (visit astm.org for downloadable standards). Clearance or verification should be provided by a third party testing firm. Find a competent one. Several years ago on a dry-out, the project manager called me yelling and screaming after a week of drying, saying we made the concrete even more wet! He indicated that the testing company (who was the flooring supplier that wanted to place a sealer on the floor instead of drying it) used the MVER (ASTM #1869) test on the floor while we were drying. The testing company said the slab was worse (or more wet) because we increased the evaporation rate from 11 to 16 lbs per 1000 square feet! I agreed that the evaporation increased and told him that is how we dry materials - by evaporating the excess water! The MVER test is a poor indicator regarding moisture content of the concrete because it only measures the evaporation rate off the surface. This antiquated test is truly outdated and often poorly applied as it is easily duped by variations in air temperature, humidity ratio and surface conditions of the concrete. The ERH test gives you a relative humidity target at a certain temperature, for instance, 75ºF. The ERH test is also not useful when drying at elevated temperatures because the relative humidity lowers as you heat the slab above 75ºF. Possibly, if you convert to dew point (a dry side target of 65% relative humidity at 70ºF is equal to 57.7ºF dew point), you may be able to monitor the slab at elevated temperatures using dew point. This may give you an idea of where you are heading in relation to your target before you cool down for confirmation testing.

As always, your job is to bring concrete back to normal equilibrium with its environment. I also advise you to read Howard Kanare’s book with the Portland Cement Association titled Concrete Floors and Moisture. Also, the World of Concrete Trade Show in Las Vegas is an eye-opening experience. As always, happy drying and see you in class!

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Charles A. Boutall II, (Chuck) joined the Restoration Industry in 1988 and took his first IICUC courses from Claude Blackburn, Jeff Bishop, Ruth Travis and Jim Caulfield. He has been an IICUC-RC member since 1988 except for two years. He is a native of New Orleans and has an Associates in Electrical Engineering. 

He is co-owner of Air Quality Specialists which provides
Courses and Consulting in Commercial losses with a specialty in Timber and Concrete Drying as well as Climate Control for Surface Preparation and Coating Projects. AQS focuses on IICR’s WRT & CDS courses and several Specialty Restoration courses approved for IICRC’s Continuing Education Credits.

Presently Chuck is Director of Education at The Restoration Technical Institute in Reading, PA. Here he trains with some of the best instructors in the industry and enjoys the ability to have a Three story 1890’s Fabric mill as a lab and hands on training facility.

He began his career as a Product support Representative at Xerox in New Orleans then to San Jose, CA as a Sr. Field Engineer for National Semiconductor Corporation providing Installation and Repair of Mainframe computers and Laser Barcode Scanning systems for the US military all the way to Grocery stores.

At Munters Cargocaire Corporation he was a District Manager for the Moisture Control Services division then moved on to Sr. Application Engineer for Consultation, design and build of dehumidification projects throughout the US and Central America. Here Chuck provided dehumidification services ranging from dog food drying to climate control on Nuclear submarines and the Space Shuttle.

Moving on to Sponge-Jet Inc. Where he planned and implemented the start-up of a new low – dust blasting technology in the Southern United States.

Afterwards, Chuck was National Sales Manager at Eagle Industries – Containment & Abatement Products, where he directed Product Development and new product launches.

He was also owner of Air Quest Systems, a Manufacturer of Custom Desiccant Dehumidifiers, Large Refrigerant Dehumidifiers and Custom Portable Air Conditioning and Heating systems.

Chuck is probably best known for his no nonsense style of Speaking at the Water Strategies Cruises, Dri-Eaz’s Restorative Drying Symposiums, the Water Loss Institute, ASCR National, Connections East and West, DRC Canada, Experience East & West and moderator of Specialty Drying Roundtable on the Water Strategies Cruise. 

He has also written a series of articles about Commercial Drying for Restoration and Remediation Magazines.

I have dried millions of square feet of structure, hundreds of thousands of books and documents and designed permanent systems for various manufacturing and storage projects over my 31 year career as an Application Engineer.

Recommended Content

JOIN TODAY
To unlock your recommendations.

Already have an account? Sign In

  • mold remediation

    Fighting Mold and Bacteria Damage

    Successful mold remediation can be multidisciplinary,...
    Contamination Restoration & Remediation​
    By: Josh Woolen
  • certifications and licenses for restoration professionals

    Certifications and Licenses Every Restoration Company Needs

    Restoration companies need to make sure they have the...
    Restoration Training/Education
    By: Sharon Elzarat
  • a wall covered in moss and fungus

    Zero Tolerance for Toxic Molds: Essential Steps for Successful Remediation

    Understanding the importance of zero tolerance for toxic...
    Mold Remediation
    By: Michael A. Pinto CSP, SMS, CMP, RTPE, FLS, ERS and Kendra Seymour
You must login or register in order to post a comment.

Report Abusive Comment

Manage My Account
  • eNewsletter
  • Online Registration
  • Subscription Customer Service
  • Manage My Preferences

More Videos

Popular Stories

Pop Art Female Superhero Punches a Masked Villain

TPAs vs. Independence: The Restoration Industry’s Own Version of the Cola Wars

RIA Carrier Advocate Mark Springer

Turning the Page: A New Era of Trust and Collaboration in Restoration

Paul Davis Restoration Leadership Team

Justin Graham Expands Paul Davis Restoration’s Reach with Acquisition of Greater Seattle Franchise

Submit Your New Product/Technology to R&R!

Would you like to promote a new restoration, remediation or cleaning product/technology with Restoration & Remediation? Fill out the question below to start your submission:

Events

September 3, 2025

The Experience Convention and Trade Show

The Experience Convention & Trade Show logoJoin us in Las Vegas for The Experience Convention & Trade Show, the leading event for cleaning, restoration, and remediation pros, packed with hands-on demos, expert speakers, and high-impact networking. Happening September 3–5, 2025 at Caesars Forum—this is where the industry comes to learn, connect, and grow!

View All Submit An Event

Poll

Doffing PPE

When you are doffing your PPE, do you sanitize between every step?
View Results Poll Archive

Products

The Cleaning, Restoration, Inspection, and Safety Glossary

The Cleaning, Restoration, Inspection, and Safety Glossary

The Cleaning, Restoration, Inspection, and Safety Glossary.

See More Products
Prepare for CATASTROPHE with R&R!

Related Articles

  • boutall commercial buildings emc beach

    Moisture Mapping Large Commercial Buildings

    See More
  • Procedures and Processes for Proper Drying

    See More
  • Busting the Myths About Desiccants

    See More

Related Products

See More Products
  • M:\General Shared\__AEC Store Katie Z\AEC Store\Images\r&r\new site\waterinbuildings.gif

    Water in Buildings: An Architect's Guide to Moisture and Mold

  • secrets-of-insurance-game.jpg

    Secrets of the Insurance Game

  • insurance.png

    2025 National Renovation & Insurance Repair Estimator

See More Products
×

Stay ahead of the curve with our eNewsletters.

Get the latest industry updates tailored your way.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Directories
    • Store
    • Want More
    • Submit a Press Release
  • SIGN UP TODAY
    • Create Account
    • eNewsletters
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Reprints
    • Marketing Services
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing