URGENT HELP!! Do you HAVE to check the moisture content of concrete installing...

[Floorist]

Agree. Alot has to do with whether the slab was poured on sand, over plastic, on a shady side, in the desert, below or above grade, as well.

Had a woman want me to put 300 yards vinyl on 30 day old concrete, hell no. Guy who did it got sued when it failed.

 

[Commercial Floor Rep]

Sorry for being late to the party on this one...

I have been through extensive training and education from the leading experts in the industry on this topic. I've written articles on this topic, taught for several years about this topic, created several presentations on this topic, and deal with this topic on a daily basis...

I wanted to try and clarify something for some of you on the old adage about 28 days / inch of slab thickness. That statement has been made forever but it's only partially correct. The actual rule is approximately 28 days per inch of slab thickness for a slab curing and exposed from one side (top or bottom) ONCE THE ENVELOPE OF THE BUILDING IS SEALED AND THE SPACE IS ENVIRONMENTALLY CONTROLLED. The slab MUST also have an intact vapor retarder in contact with the bottom of the slab for on-grade or below-grade slabs.

Yes, curing MAY occur before that period of time, but when a traditional porous slab is exposed to the fluctuations of exterior environmental conditions, especially increases and decreases in relative humidity, then the slab CAN and WILL gain moisture whenever the ambient relative humidity is higher than the internal relative humidity in the slab.

You also CANNOT do an accurate in-situ Rh test, or CaCl (Calcium Chloride) test until the envelope of the building is sealed and the environment is at normal operating temperature with an ambient Rh blow 65%.

The porosity and mix design can also be modified with things such as silica densifiers, sealers, curing agents, and moisture emission inhibitors as well as over power trowelling to change the porosity and MVER (Moisture Vapor Emission Rate) of the slab. This can drastically effect cure times.

In other words, if you have a traditional porous slab and it's being periodically exposed to rain and snow, or even high humidity weather, if the ambient Rh above the slab is higher than the in-situ Rh (Remember rain = 100% Rh), no curing is happening until the ambient relative humidity above the slab is lower than the internal or in-situ Rh in the slab. It's physics (read Boyle's gas laws). The slab contains a pressure gradient of relative humidity (Rh is the amount of moisture (water in a gaseous form, not liquid) with the highest levels being at the bottom of the slab and as you come up through the slab, this pressure gradient decreases, assuming the top of the slab is exposed to open air. When we cap the slab with a resilient floor, or any hard surface floor that slows the loss of this moisture from the slab, the pressure gradient begins to equalize within the slab causing the Rh (and pH) to increase at the surface of the slab. This is why in-situ Rh is conducted at exactly 40% of the slab depth for a slab curing from one side. That depth has been scientifically proven to be consistent with the in-situ Rh level after the slab is covered with a resilient floor covering.

While moisture is the driver or carrier, the actual problem comes in with the alkalinity salts that are moved up through the slab with the moisture that are deposited at the glue level underneath the floor. This increased alkalinity can be extremely high, many times reaching pH levels well above 12. Bear in mind that the pH scale is exponential in its measurement. The pH scale goes from 1-14. On the pH scale 7 is neutral. Anything below 7 is acidic and anything above 7 is alkaline. For example, when we move from 7 to 8 on the scale, the amount of alkalinity is 10 times greater, 7 to 9 is 100 times greater, 7-10 is 1000 times greater, and so on. This is the same thing that occurs with efflorescence on grout. Those are the salt crystals that are left on the surface of the grout from moisture vapor moving through the grout, evaporating at the surface and leaving behind the dissolved salts on the surface of the grout. Exactly what happens under a resilient floor, except the salts are left at the glue level.

So, if you have an adhesive that allows a maximum pH of 9 and you're at 10 when tested, then you aren't just a "little" higher, your 10 times greater alkalinity than what the adhesive can handle.

Alkalinity is a problem because with all of the water based, low VOC adhesives we have to use today, increased pH will break down the bonds in the adhesive and cause it to re-emulsify. This is why when you have a moisture issue, the glue smells terrible and looks like thinned down mayonnaise.

With regard to the requirement for moisture testing, every manufacturer in the industry REQUIRES every slab be tested BECAUSE of ASTM F-710 Standard Practice for Preparing Concrete Substrates to Receive Resilient Floor Coverings. This standard not only requires moisture testing, but porosity testing, pH testing, and floor flatness testing. It also states that ALL sealers, parting compounds, primers, curing compounds, or any other additive that can cause interference with the adhesive bond must be removed and only by mechanical means. In other words, it prohibits the use of any type of chemical removal of these materials from the substrate. Additionally, old school practices like acid etching, or muriatic acid washing to reduce pH on the surface of the slab are also prohibited. pH can actually be reduced simply by cleaning the surface of the slab with clean water. This may have to be repeated, but it will permanently lower the surface pH. There are few "tricks of the trade" to do this easier and if someone wants to know what they are I'll be happy to share, but suffice it to say that pH is as important, if not more important, than moisture testing to determine the success of an installation. ASTM F-710 defers to either ASTM F-2170 for in-situ Relative Humidity testing and ASTM F-1869 for CaCl testing.

Many manufacturers no longer recognize ASTM F-1869 as a valid form of testing as there are inconsistencies that can lead to a false high or false low test. The major drawback is that it only tests the top 3/4" of depth of the concrete. Since moisture is in a pressure gradient from highest levels at the bottom of the slab to lowest at the surface you can see that this could lead to an erroneous assumption that the slab is dry.

Caveat Emptor - there are correct ways to deal with high moisture to get a floor installed in high moisture situations and there are incorrect ways. There are literally tons of products in our industry to deal with moisture. Unfortunately, the vast majority are poorly tested, incorrectly installed, or just simply don't work as advertised. Be careful and do extensive research on whatever choice of products that you use to deal with a high moisture installation. Understand the nuances and speak to the products technical support PRIOR to using any product. Make sure you document everything that you do and make sure that you fully understand the warranty implications of using the product under a given floor covering. Legally, if you don't document then it didn't get done. You saying you did it after the fact is not good enough to hold up in court. It needs to be in writing and pictures (recordings) should be done when the testing is conducted for additional support.

Be happy to answer any questions regarding this topic as there is far more to it than what I've mentioned here, but just wanted to try and shed some light to hopefully prevent someone from making an error from partial information. Hope this helps.

 

[Csason]

Hell we drill and moisture testers on anything over 5000 dollars lol that’s the method we use

 

[Commercial Floor Rep]

Hell we drill and moisture testers on anything over 5000 dollars lol that’s the method we use

When I get the question..."should I test every slab?" Technically yes, practically not really. You as an installer or retailer have to determine what level of financial risk, you're willing to take. For you it's $5000, for others it might be $2000, believe it or not for some it's $0 and they do test everything.

Are you going to test every 6'x6' bathroom? Probably not, and that's ok as long as if things go south, you can take care of the customer.

Don't forget though, that the costs of materials and labor are what they are, but how much financial impact does a problem have on your reputation as a professional? It's something that I think many forget to account for, and probably more costly in the long run than the actual replacement of the flooring.

 

[Csason]

When I get the question..."should I test every slab?" Technically yes, practically not really. You as an installer or retailer have to determine what level of financial risk, you're willing to take. For you it's $5000, for others it might be $2000, believe it or not for some it's $0 and they do test everything.

Are you going to test every 6'x6' bathroom? Probably not, and that's ok as long as if things go south, you can take care of the customer.

Don't forget though, that the costs of materials and labor are what they are, but how much financial impact does a problem have on your reputation as a professional? It's something that I think many forget to account for, and probably more costly in the long run than the actual replacement of the flooring.

I have a couple guys I do work for that KNOW I have beat every inspection that’s been “demanded” so they don’t take chance with “variables” .
I start a welding job tomorrow for Hyatt and another for Marriot following that, both sports floor and behind that a Dollar store welding job all of them are worth testing for if it was my house I’d have to ask the question, What IF the floor buckled and the manufacturer said it was moisture and I didn’t have proof otherwise?

 

[havasu]

Sorry for being late to the party on this one...

I have been through extensive training and education from the leading experts in the industry on this topic. I've written articles on this topic, taught for several years about this topic, created several presentations on this topic, and deal with this topic on a daily basis...

I wanted to try and clarify something for some of you on the old adage about 28 days / inch of slab thickness. That statement has been made forever but it's only partially correct. The actual rule is approximately 28 days per inch of slab thickness for a slab curing and exposed from one side (top or bottom) ONCE THE ENVELOPE OF THE BUILDING IS SEALED AND THE SPACE IS ENVIRONMENTALLY CONTROLLED. The slab MUST also have an intact vapor retarder in contact with the bottom of the slab for on-grade or below-grade slabs.

Yes, curing MAY occur before that period of time, but when a traditional porous slab is exposed to the fluctuations of exterior environmental conditions, especially increases and decreases in relative humidity, then the slab CAN and WILL gain moisture whenever the ambient relative humidity is higher than the internal relative humidity in the slab.

You also CANNOT do an accurate in-situ Rh test, or CaCl (Calcium Chloride) test until the envelope of the building is sealed and the environment is at normal operating temperature with an ambient Rh blow 65%.

The porosity and mix design can also be modified with things such as silica densifiers, sealers, curing agents, and moisture emission inhibitors as well as over power trowelling to change the porosity and MVER (Moisture Vapor Emission Rate) of the slab. This can drastically effect cure times.

In other words, if you have a traditional porous slab and it's being periodically exposed to rain and snow, or even high humidity weather, if the ambient Rh above the slab is higher than the in-situ Rh (Remember rain = 100% Rh), no curing is happening until the ambient relative humidity above the slab is lower than the internal or in-situ Rh in the slab. It's physics (read Boyle's gas laws). The slab contains a pressure gradient of relative humidity (Rh is the amount of moisture (water in a gaseous form, not liquid) with the highest levels being at the bottom of the slab and as you come up through the slab, this pressure gradient decreases, assuming the top of the slab is exposed to open air. When we cap the slab with a resilient floor, or any hard surface floor that slows the loss of this moisture from the slab, the pressure gradient begins to equalize within the slab causing the Rh (and pH) to increase at the surface of the slab. This is why in-situ Rh is conducted at exactly 40% of the slab depth for a slab curing from one side. That depth has been scientifically proven to be consistent with the in-situ Rh level after the slab is covered with a resilient floor covering.

While moisture is the driver or carrier, the actual problem comes in with the alkalinity salts that are moved up through the slab with the moisture that are deposited at the glue level underneath the floor. This increased alkalinity can be extremely high, many times reaching pH levels well above 12. Bear in mind that the pH scale is exponential in its measurement. The pH scale goes from 1-14. On the pH scale 7 is neutral. Anything below 7 is acidic and anything above 7 is alkaline. For example, when we move from 7 to 8 on the scale, the amount of alkalinity is 10 times greater, 7 to 9 is 100 times greater, 7-10 is 1000 times greater, and so on. This is the same thing that occurs with efflorescence on grout. Those are the salt crystals that are left on the surface of the grout from moisture vapor moving through the grout, evaporating at the surface and leaving behind the dissolved salts on the surface of the grout. Exactly what happens under a resilient floor, except the salts are left at the glue level.

So, if you have an adhesive that allows a maximum pH of 9 and you're at 10 when tested, then you aren't just a "little" higher, your 10 times greater alkalinity than what the adhesive can handle.

Alkalinity is a problem because with all of the water based, low VOC adhesives we have to use today, increased pH will break down the bonds in the adhesive and cause it to re-emulsify. This is why when you have a moisture issue, the glue smells terrible and looks like thinned down mayonnaise.

With regard to the requirement for moisture testing, every manufacturer in the industry REQUIRES every slab be tested BECAUSE of ASTM F-710 Standard Practice for Preparing Concrete Substrates to Receive Resilient Floor Coverings. This standard not only requires moisture testing, but porosity testing, pH testing, and floor flatness testing. It also states that ALL sealers, parting compounds, primers, curing compounds, or any other additive that can cause interference with the adhesive bond must be removed and only by mechanical means. In other words, it prohibits the use of any type of chemical removal of these materials from the substrate. Additionally, old school practices like acid etching, or muriatic acid washing to reduce pH on the surface of the slab are also prohibited. pH can actually be reduced simply by cleaning the surface of the slab with clean water. This may have to be repeated, but it will permanently lower the surface pH. There are few "tricks of the trade" to do this easier and if someone wants to know what they are I'll be happy to share, but suffice it to say that pH is as important, if not more important, than moisture testing to determine the success of an installation. ASTM F-710 defers to either ASTM F-2170 for in-situ Relative Humidity testing and ASTM F-1869 for CaCl testing.

Many manufacturers no longer recognize ASTM F-1869 as a valid form of testing as there are inconsistencies that can lead to a false high or false low test. The major drawback is that it only tests the top 3/4" of depth of the concrete. Since moisture is in a pressure gradient from highest levels at the bottom of the slab to lowest at the surface you can see that this could lead to an erroneous assumption that the slab is dry.

Caveat Emptor - there are correct ways to deal with high moisture to get a floor installed in high moisture situations and there are incorrect ways. There are literally tons of products in our industry to deal with moisture. Unfortunately, the vast majority are poorly tested, incorrectly installed, or just simply don't work as advertised. Be careful and do extensive research on whatever choice of products that you use to deal with a high moisture installation. Understand the nuances and speak to the products technical support PRIOR to using any product. Make sure you document everything that you do and make sure that you fully understand the warranty implications of using the product under a given floor covering. Legally, if you don't document then it didn't get done. You saying you did it after the fact is not good enough to hold up in court. It needs to be in writing and pictures (recordings) should be done when the testing is conducted for additional support.

Be happy to answer any questions regarding this topic as there is far more to it than what I've mentioned here, but just wanted to try and shed some light to hopefully prevent someone from making an error from partial information. Hope this helps.

We all really appreciate this great information!

 

[Commercial Floor Rep]

You guys are most welcome! It's a complicated topic and it's always changing. There are enough "gotchas", BS marketing, gray areas, pitfalls, and myths on this topic to sink a small naval vessel or two. Right now, on the commercial side, it goes from one extreme to the other. Some Architects, GC's, and flooring contractors have a pretty good basic knowledge and understanding and even after 15 to 20 years of education, some of them still have their heads stuck in the sand and truly believe that this all a made-up issue to sell more products.

The reality is that construction schedules have become so compressed to try and shorten the builder's exposure for the construction loans that they simply don't allow enough time for concrete to properly wet cure. So, they (the builders) start coming up with all these "solutions" which for the most part cause bonding issues, then we (the flooring industry) see an opportunity and start inventing products (sealers and adhesives) that also complicate the installation and then the concrete industry starts modifying concrete mixes with "vapor suppression" additives and at the end of the day the poor installer has to bear the burden to make all this crap work together and provide a warranty for their work. It's just ridiculous where we've come to.

Interestingly, as many people begin to realize that "waterproof" floors aren't really aren't all they are cracked up to be, the retailers are slowly starting to drift back towards glue down. The problem is they haven't been dealing with the changes in concrete, moisture, pH, site conditions, adhesive technologies, etc. and everyone is out there thinking there is a "silver bullet" to solve the issue and anybody that says otherwise is terribly misinformed. So, they try this "roll on", or this "spray and pray" or this "magical adhesive" and they just end up either performing a field experiment in field chemistry and more often adding another questionable layer to a "crap sandwich". Every solution to this issue comes with tradeoffs and negatives, all of them.

Today, to properly install a floor, you have to be a mechanical engineer, a meteorologist, a chemical engineer, and a legal expert. And people wonder why our industry is suffering from an installation crisis. Who wants to assume all this liability? SMH