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Relative Humidity Testing in Lightweight Concrete

Relative Humidity Testing in Lightweight Concrete

ASTM F2170 provides the standard for using relative humidity (RH) testing for flooring and concrete professionals when measuring moisture content in concrete slabs. The ASTM provides precise guidelines for RH testing methods but does not address the limitations of the testing equipment.

Limitations of In-situ relative humidity testing equipment.

A picture of a floor being removed probably for relative humidity issues.When testing relative humidity (RH) in lightweight concrete, the limitations of the testing equipment get overlooked.  Testing equipment limitations have a significant influence on the data that is acquired when testing.  It can significantly skew the results leading to costly RH mitigation.  Since in-situ testing equipment has a significant impact when testing lightweight concrete, let’s dig a little deeper to get to a better understanding of some of these limitations.

One of the most significant limitations that a sensor has is how long it can be in an environment with a relative humidity of 80% or higher without damaging the electronic sensor.  The little device in each probe that measures the humidity does not work well in high humidity environments for extended periods of time without it being damaged or needing to be recalibrated.  The type of sensor that is being used needs to be addressed to maintain testing within manufacturer recommendations.

The problem with Wagner is that for years they only made a Wagner 4.0 probe.

The go-to In-situ probe has been and continues to be the Wagner probes.  The problem with the Wagner is that for years they only made a Wagner 4.0 probe.  The issue with the Wagner 4.0 probe is that it is a single-use probe and gets installed within a few minutes of drilling the hole.  When you drill a hole in lightweight concrete, you pulverize the aggregate releasing moisture into the hole, making a not-so-ideal situation even more problematic by increasing the relative humidity within the hole (most likely above 80% and potentially into the high 90% range). The frustrating part is that ASTM 2170 and the Wagner 4.0 manufacturer recommended testing instructions do not address the concern for the spike in relative humidity in the hole at the time of installation.  We are not able to provide you with an affiliate link to the Wagner 4.O; however, we can send you to check out a Tramex.  We will do a separate blog post on Tramex testing equipment at a later date.

The new Wagner 5.0 probe that is more viable for lightweight concrete relative humidity testing.

Wagner does now manufacture a multiple-use Wagner 5.0 probe that can be used to test lightweight concrete that has an initial spike of RH after drilling the hole.  With the Wagner 5.0 probe, you install a sleeve after cleaning the dust out of the hole. After 72 hours, you can install the probe sensor after the hole has had time to acclimatize to a more realistic relative humidity.  It is still essential to make sure you monitor the relative humidity during your 1st few test holes and make sure the probes are not getting exposed to excessive RH that may give false or skewed readings.  Click here to check out the new Wagner 5.0.

The typical component in most In-situ relative humidity sensors is made by Senserion and has limitations not identified by the probe manufactures.

Let’s now talk about the little sensor that measures the humidity that is in most of the relative humidity in-situ probes on the market today. Sensirion, an electronics manufacturing company make the tiny sensors.  Sensirion is the leading manufacturer of high-quality sensors and sensor solutions for the measurement and control of humidity, and of gas and liquid flows.  If you want to do a little research on your own, you can go to their website at to learn a little more about the limitation of the actual sensor that lives in the in-situ probe.

What are the standard operating ranges of the Sensirion sensors?

Wagner 4.0 probes get installed a few minutes after drilling and cleaning the test hole exposing the probes to potentially high relative humidity (RH) for 72 hours if testing per ASTM F2170.  If you go digging around and find the normal operating range for the Sensirion sensors.  You will find that the sensor product data sheet shows the best performance when operated within recommended normal temperature and a humidity range of 5 degrees Celsius – 60 degrees Celsius and 20%RH – 80%RH, respectively.  Long-term exposure to conditions outside the normal range, especially at high humidity, may temporarily offset the RH signal (e.g., +3% after 60hours kept at >80%RH).  You are going to get skewed readings using a Wagner 4.0 probe system in lightweight concrete when exposing the probe to the hole when the humidity is at its highest above those as mentioned above normal operating range.




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Fire Door Gap Gauge for your fire rated door

Fire Door Gap Gauge

The Fire Door Gap Gauge for your fire door by All Things Inspector is by far the best multi-use fire door gap gauge on the market.  You will not find another door gap gauge on the market that boasts a beer bottle opener to support your after work activities.  It also has a machined 3" measurement tool, a material thickness gauge and it will be attached to your keychain so it is by your side when you need it most.

A top profile picture of the best fire door gap gauge.The Fire Door Gap Gauge will be by your side when you need it.

Is more accurate than a tape measure when checking a fire rated door for NFPA 80 required clearances. It is compact and easy to use with it's machined steps to identify the following margins 1/8", 3/8", 1/4", 3/8", 1/2" 5/8" and 3/4" for your required door gaps.  It also has a material thickness gauge with the ability to measure the following sizes 20ga, 16ga, 15ga, 14ga, 1/8", 10ga, 3/16" and 1/4" of sheet goods and wire sizes. Plus it will open your beer or soda after work.  If you are not 100% satisfied with the fire door gap gauge just return it to All Things Inspector and they will provide a full refund with no questions asked.

The cool thing about The Door Gap Gauge is that it is a multi-use tool that brings convenience for many.

Are you an Inspector, Quality Control, Trades-person or Architect that needs to measure that item on the 19th floor. Well, you are in luck if you have the Fire Door Gap Gauge because it just came to your rescue.  That same day you are finishing up work and the crew decides to meet at the park and have a couple of Beer’s and you pull out your Fire Door Gap Gauge and you have been rescued again.  This tool is not only designed to help save lives, but will rescue you when you least expect it.  If your time is valuable you need a Fire Door Gap Gauge.

Check Out The Fire Door Gap Gauge Here.

Fire Rated Door Checklist.

Door Gap Gauge

The Fire Door Gap Gauge

The fire door gap gauge is a must-have tool for building inspectors, IORs, Fire Marshals and AHJs for inspection of non-rated and rated fire doors in warehouses, office buildings, hospitals, and residential high rises.

Watch the video to find out for your self that the Fire Door Gap Gauge is a simple to use, highly efficient “must have” tool that every inspector, fire marshal, commercial property/maintenance manager and fire department needs in their toolbox.

Checking for and maintaining Fire Door compliance has not been easier with the fire door gap gauge.  Fire door compliance should be at the forefront of new construction and maintenance of existing facilities everywhere.


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Elevator pit – Are Fire Sprinklers required?

Currently, I have heard a lot of debate about whether an elevator pit fire sprinkler will have to be installed the bottom of an elevator pit to a traction elevator? We have a sprinkler in the elevator pit of a traction elevator, and the AHJ says that fire sprinkler can be removed and is not needed per NFPA -13 – The AHJ indicated that if the fire sprinkler was to remain in its current location that it would have to have dedicated monitoring and shunt the elevator or that we can remove the said fire sprinkler. Either way would be acceptable to the local AHJ, and they did not seem to have a preference.

A picture of a hydraulic elevator pit.
An elevator pit of a hydraulic elevator.

The second debate is where I am reaching out for further opinion. It seems very cut in dry that per 2013 NFPA – that the sprinklers not required.  This debate is whether the elevator inspector will enforce the sprinkler in the elevator pit?  ASME A17.1 – 2004 Safety Code for Elevators and Escalators seems only to tell you what to do if there is a fire sprinkler in the elevator pit. Honestly, I have not read the whole thing and do not have a searchable copy.

Who has jurisdiction over the sprinkler in the elevator pit?  The local AHJ or the State Elevator Inspector?

During my investigation to determine whether to remove or leave the sprinkler. I also ran across an article from William E Koffel, P.E about Sprinklers in Elevator Hoistways and Machine Rooms.  This article is old since it references NFPA 13, 1989, but does bring up a relevant subject and that is the fact that it talks about the buildup of trash and debris that has collected at the bottom of the shaft.  That over time will provide a potential fire load at the bottom of the elevator pit.  Has anyone seen this article roaming the internet, but more importantly is the State Elevator Inspector in forcing a sprinkler to be installed because of the potential for the buildup of refuse in the bottom of the elevator pit because of the scenario presented in this article.

A Circular Letter E-99-1 – Shunt Trips for Sprinkler in Elevator Pits was presented to me to substantiate leaving the sprinkler and not having to shunt the elevator.  This Circular is from the State of California Department of Industrial Relations and seems to indicate that they will not require the shunt trip on the sprinklers located two feet or less from the elevator pit floor.  When I approached the city AHJ about this circular letter, he indicated that he was aware of it and that if the fire sprinkler was to remain that it would have to be monitored and shunt the elevator.

I was hoping that someone with a passion for the NFPA 13,  ASME 17.1 and California Building Code can help myself and other individuals in similar occupations make a little more sense of who has jurisdiction over the elevator pit and if a fire sprinkler should be required in a California elevator pit.

To learn more about the requirements of fire sprinklers in elevator pits and access NFPA 13.

To check the closing pressure on elevator doors purchase one of our door pressure gauges.

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Building Code Discussion Group

The Building Code Discussion Group

Building Code Discussion Group is one of the largest professional platforms on the World Wide Web. A platform for building, fire, MPE, accessibility/ADA code discussions and technical opinions. This Building Code Discussion Group has enough forums to cover all the necessary building code topics and disciplines. The Building Code Discussion Group is sponsored by Interwest Consulting Group.

THE BCDG…. is a powerful Online Community available to “Premium Members” that can access all the features afforded by the BCDG. The BCDG forums are available free for read-only access (registration is required). Another solution created by Imad Naffa since 1995. One of the largest, most-active, professional Building Code Discussions Group on the World Wide Web. A platform for building, fire, MPE, accessibility/ADA code discussions and technical opinions. Over 24 forums make up the BCDG that cover all building code topics and disciplines.

Explaining, educating, interpreting and deciphering the complex building codes for the masses (novices and experts alike) is the goal here! If you build, design, inspect, engineer, plan check, review, in a construction or design training program or deal with the building permit process – this is your place. International storehouse for building code discussions & resources, CASp and SB 1608, accessibility, ADA, emerging technologies & online collaboration. National participants/experts. The #1 searchable source for building/construction, technical support & building/fire codes learning.

If you would like to check out All Things Inspector’s building code forum feel free to take a look.  Our building code forum or discussion group is not ad-free, but we don’t charge you for a premium membership to participate in our forum. All you have to do to post or ask a question is to register to our site as a free member.  We do support our forum and blog efforts through profits from our online store.

Are you an inspector, architect, contractor, safety professional and have a topic you are an expert in and would like to share it with the world.  We would like to encourage you to become a guest blogger. If you want to learn more about becoming a guest blogger please visit our guest blogger page.

Building Code Discussion Group

Other building code discussion groups.



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The Building Code Forum

The Building Code Forum

The Building Code Forum is a robust forum message board for building code talk, sharing information related to the building industry to include all construction codes.  The Building Code Forum is a robust forum with over 14,000 discussions, over 160,000 messages and over 5,000 members.  If you have a building code related questions and are seeking answers spend a few minutes and search for it here and if you don’t find what you are looking for register and post a question and most likely someone will help you to come up with an answer.

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Free Building Code With Online Access

Free Building Code

This link provides you searchable online free building code anywhere you have an internet connection for just about all 50 states. This site provides access to 2010 – 2016 building codes based on your jurisdiction.

Free Building Code Free Building Code

Other building code free resources.

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Mike Holt Enterprises | electrical training and forum

A picture of Mike Holt's website

Mike Holt Enterprises for over 25 years has been the leader in Electrical Continuing Education.  They are your One-Stop electrical training resource. Mike Holt Enterprises was created by a Master Electrician for Electricians, Inspectors, Contractors, Electrical Instructors, Building Code Officials and Engineers.

Visit to find, tips for passing an electrical exam,  answers to technical questions or even post a question in their electrical forum.   Mike Holt’s electrical forum has over a million posts where you can search to find answers to your questions or post your own question to get technical advise.  Their website is a great resource if you are looking for electrical code resources as they have a robust online store where you can find almost any electrical training material that you may need to purchase.

Mike Holt worked his way up through the electrical trade from apprentice to master electrician and electrical contractor. In 1973, he began teaching electrical classes, and by 1980 he had stopped contracting and was focused solely on training. Now, Holt is nationally recognized as an expert on the NEC and is one of the most knowledgeable electrical instructors in the US. His series of books and videos are used across the country by numerous training centers, electricians, and engineers. His books include Understanding the National Electrical Code, Grounding vs. Bonding. After dropping out of high school, Holt later received his MBA from the University of Miami.

Mike’s also an eight-time National Barefoot Water-ski Champion,  has set many national records and competed in four World Championships. Mike and his wife Linda reside in Central Florida and are the parents of seven children.

Mike’s personal educational journey impacts the way he designs training. As a young man he was unable to complete his high school diploma due to life circumstances, but realizing that success depends on one’s education, he immediately attained his GED. Then, ten years later, he attended the University of Miami’s Graduate School for a Master’s in Business Administration. Because of this experience, he understands the needs of his students, and strongly encourages and motivates them to continue their own education. He has never lost sight of how hard it can be for students who are intimidated by the Code, by a school, or by their own feelings about learning. His story has impacted the way he designs his materials and continues to guide him to this day.

Please visit  Mike Holt Enterprises at or visit his YouTube channel which has over 27,000 subscribers.

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Hiring a certified third party firm to perform your Lightweight Concrete In-situ Relative Humidity Testing per ASTM 2170.

Why is it important to hire a neutral third part when having your Lightweight Concrete In-situ Relative Humidity Testing performed per ASTM 2170?

What certifications are out there and what are the best certifications?