What to Look for in Professional Products for Vapor Sealing Concrete Slab


All of the problems associated with moisture vapor movement in a concrete slab will go away in time as the slab dries, as long as there is no source of additional water into the slab. Since the most common source is moisture in the ground beneath the slab, the solution is to completely take the ground out of the equation, by sealing the bottom of the slab.

The best way to accomplish that is with a vapor barrier under the slab. Vapor retarders have been used since the 1950s. Recently, though, research has shown that the old traditional layer of 6-mil Visqueen (polyethylene plastic) under the slab is seldom effective for two main reasons:

Although it may seem water-tight, this grade of material allows a lot of water vapor to pass through. 6-mil plastic often gets damaged during placement of reinforcement and concrete, creating holes that can let a considerable amount of water vapor into the slab.

True vapor barriers allow little water vapor to penetrate. W.R....

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Anyone that has had to face a moisture problem with a concrete slab understands the damage that excess moisture can cause. Moisture in concrete can occur from a variety of sources: ground moisture that contacts the slab through either capillary action or as water vapor, high air humidity or drastic changes in relative humidity in its environment, leaking plumbing that passes through the slab, and more.

Excess moisture can cause pH changes in concrete that adversely affect adhesives. Even an excess of moisture that was retained from the original concrete mixture will cause problems if the slab was sealed prematurely.

It should be obvious – concrete starts wet. The water added to the cement, sand and aggregate mixture is necessary to form a good bond in the concrete, but it is also necessary that the moisture evaporates away from the concrete in order to let the concrete dry and to prevent flooring failures.

Adding more water may make concrete more...

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The info on this forum has been very helpfull, but I still have some questions regarding the concrete sealer.

I will start to finish my 900 sq. ft. basement in a few months, but before I begin the drywall and bathroom piping, I would like to seal the concrete. The slab and walls were poured about 5 months ago and I live in Atlanta, GA.

I will probably install a glue down engineered wood floor directly on the concrete slab, but which sealer should I use as a vapor barrier?

You mentioned a 2 part epoxy sealant, but would that be enough vapor barrier to simply glue down the wood floor later? Any brands you recommend?

I was considering a product called RadonSeal Standard http://www.radonseal.com/concrete-sealers.htm
Penetrate deep (up to 4" in concrete) and react with lime and alkalis. Bond and strengthen, reduce cracking. Harden the surface and reduce dusting. Seal against water seepage, water vapor and radon gas. Withstand high water pressure....

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Deep Penetrating Concrete Sealers Prevent Floor Covering Failures on New and Existing Concrete

When your Calcium Chloride (CaCl) test comes back higher than acceptable or the concrete’s relative humidity level is greater than 80%, you’ve got a serious problem. The critical path of construction schedule does not give you time to wait another month for the concrete to continue curing and drying.

Bone Dry has been the solution to CaCl and RH troubles in new and existing concrete.

A water based, penetrating concrete sealer, Bone Dry Pro formula penetrates through the concrete surface, fills the capillaries in the slab and produces a barrier within the concrete. The result is a permanent waterproof barrier protecting the floor coverings from moisture damage. Properly applied, Bone Dry prevents moisture based failures with their warranty for 20 years.

Concrete Moisture Mitigation System: Everything Delivered in One Convenient Package

With tight...

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Our complete product line is available to homeowners, contractors, and distributors worldwide! Protect concrete, brick, stucco, pavers and more, with our revolutionary sealers. In the heat of the Summer or below freezing temperatures this Winter, you will continue to be productive with Professional Products Direct.

Purchasing is available online or by phone -- feel free to contact us at 855-908-3837 during normal business hours, EST. If you have any questions, you can also contact us online anytime, and we'll respond within 48 hours.

SingleSeal Freeze Protect™

You'll appreciate how easy-to-use our concrete sealer is on both your indoor and outdoor concrete projects. This innovative product can be applied to surfaces year-round, in temperatures as low as 28°F.

Single Seal Freeze Protect™ may be placed on both cured and newly placed concrete by using a sprayer, roller, brush, or other applicator.

Learn more about SingleSeal Freeze...

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Applying a concrete sealer to your new or old concrete project is always a good idea. Curing and sealing the concrete will help strengthen, protect, and enhance its appearance many years to come.

Knowing which sealers to choose for your specific application is very important. Maybe you just acid stained your concrete floor or you have a stamped concrete driveway, this guide will show you the different concrete sealers and how to pick the right one.



Penetrating Sealers react chemically within the capillaries of the concrete to protect against moisture penetration and deicing chemicals. They provide invisible protection and don't usually change the surface appearance.

They help improve the durability of exterior concrete surfaces exposed to harsh weather conditions like freeze-thaw...

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After over 30 hours of researching more than 60 concrete sealers and testing and evaluating seven of them, our results are found below. We found that the Siloxa-Tek 8500 is best for most people. Its made of high quality silanes and siloxanes with a 40 percent solids content, so it’s active ingredients are stronger, less watered down and approved by the Department of Transportation. The 8500 sealer leaves a natural finish without any artificial luster or sheen leaving a natural, protected surface without ever fading.

Our Pick:

Though we like Siloxa-Tek 8500, the Okon S-40 is a less expensive alternative. It lacks the concentrated availability but is cost effective, providing durable performance at an affordable cost.

Why you should trust us

We have worked in the construction industry for more than 20 years. We’ve reviewed countless sealer products with our conclusions posted throughout this site. For this guide we also talked to a number of experts about...

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For all its strength and durability, concrete has a tendency to wick moisture from the ground. Some concrete slabs stay moist, while others puddle. Not all slabs draw moisture. Some remain completely dry. Poor drainage, proximity to groundwater sources and the depth of the water table all exacerbate the problem. When concrete slabs maintain a high moisture content, floor adhesives have difficulty sticking, which limits flooring choices.

Plastic Sheet Method

While not a quantitative test, a sheet of plastic taped to the concrete slab for 16 hours or more reveals whether the slab is prone to water vapor issues. Polyethylene is typically the plastic used, and a sheet about 18 inches square is all that’s needed. Duct tape, or something similar, must fasten the sheet securely on all four sides. If the slab is damp under the sheet after the subscribed period of time, the concrete contains excess moisture. This method does not provide a measurement of how much moisture the...

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Have you heard the phrase “What you can’t see matters?” There are several products and techniques I use that get “buried” inside the house, never to be seen again. The vapor barrier under a concrete slab is one of these. Its main purpose is to keep moisture in the soil under a concrete slab from migrating up into the house. (Remember that concrete is porous and soaks up water like a sponge.) This is a vital function because excess moisture in a slab can cause several big issues down the road. The worst problems occur with hardwood floors laid directly on top of a slab; excess moisture often causes movement, warping, or buckling over time.

It’s typical to see an inexpensive “poly” used for the sub-slab vapor barrier, but I think 15-mil Stego Wrap is a much better product for protecting homes from moisture issues. For starters, it's a lot tougher and holds up to the abuse of installing rebar and placing concrete, which can leave standard poly in shreds, defeating its...

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There would only be two possible sources of moisture that I could think of on an above grade concrete substrate.

1). Curing moisture (moisture vapor(gas) not liquid moisture), that's coming out of the slab from the original pour. I don't believe this is the case because you would see this problem everywhere. You'd have flooring warping all over the place and from your pictures that doesn't appear to be the case. This is typically only an issue if the concrete is poured over a corrugated steel non-vented pan. I would be very surprised if they used that construction method for residential apartments. It's more typical in heavy commercial applications such as a multi-story hospital.

2). Moisture of intrusion from an outside source. This can be in the form of vapor or actual liquid water. Sources for this type of moisture could be things like broken or cracked feed or drain pipes in the slab or intermittent moisture finding it's way into the slab from an exterior source such as...

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Concrete is manufactured by mixing cement, sedimentary elements, and water in appropriate amounts in order to create a precise consistency. The water is kept from evaporating out of this mix until the initial curing phase has passed, and the concrete is ready to set. At that point you want the excess moisture to evaporate from the slab into the air so that it can dry and harden.

This is a process that can take days or even weeks.

The speed of the evaporation will be determined by the temperature and humidity of the surrounding air. It will also be affected by the size of the pores in the concrete. As long as the vapor pressure in the slab is greater than that in the air, water will continue to evaporate from it.

If excess moisture is present in a concrete slab when an impermeable surface treatment is installed, it will become trapped under that covering. Over time, hydrostatic pressure will force that moisture upwards and can cause bubbles in surface...

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Vapor barriers are put in place to control the amount of moisture that can enter a building space. By decreasing the moisture content of the air you decrease the amount of mold-related infestations. You also increase the energy efficiency of the house by lessening the air exchange between the exterior and interior of the building. It is not uncommon that in the speed of building the inclusion of a vapor barrier is overlooked (it is commonly specified in the notes of the plan set and not on the actual page of the plan you are working on). To correct a concrete slab that was poured without a vapor barrier you can apply an effective liquid vapor barrier coating to the top surface of the slab. This isn't your call however, you must get approval from the engineer and building inspector before starting this...

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For sealing concrete floor slabs to reduce the amount of water vapour emanating from the concrete. Suitable for use on concrete slabs prior to using Selleys Liquid Nails Direct Stick Timber Flooring Adhesive to lay timber flooring.

NOTE: Water vapour from a concrete slab can affect wooden flooring overlays.

Application of a suitable moisture vapour barrier such as VBS can reduce the chance of problems developing with wooden floors at a later stage.

Product Range

Product Code: 9300697114648

Size & Pack Type: 3.6 lit. two part epoxy kit Colour: Dark green when mixed

Technical Details and Performance


Yellow (epoxy resin)

Hardener colour

Blue (amine based)

When Mixed

Green thixotropic liquid suitable for brush or roller application


One full pack is sufficient for 20m2 per coat when used at 6m2 per litre. Two coats may be required in case of very porous concrete or very...

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Concrete slab cracks at control joints:

This article describes the causes, evaluation, and repair of cracks at control joints in poured concrete slabs or floors.

Are cracks at control joints or expansion joints in concrete a problem? Are control joints always needed in poured concrete? Recommended methods for sealing cracks in concrete floors & slabs

This article series describes how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

Green links show where you are. © Copyright 2017 InspectApedia.com, All Rights Reserved.

How to Use & Inspect Control Joints in Poured Concrete Slabs

Here we focus on control joints needed in poured concrete floor...

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Tomorrow is moving day, saying goodbye to Cambridge and hello to Lincoln, Massachusetts. Our new house requires a little history lesson. In the bad old days people dug down into the earth to make a basement foundation for a house. For hundreds if not thousands of years these primitive people stored roots, boxes, and other junk down in this basement while they lived in various floors built well above the ground level. Above the top floor they built an attic in which to store more junk. This attic became very handy in the 1970s when people looked for a place to put insulation, a whole-house fan, and other energy-saving devices.

Fortunately for mankind, in the 1960s a group of MIT and Harvard architecture geniuses came along and designed the Deck House kits. Why have a contractor assemble building materials and the local drunkards on-site to frame a house when the thing could be precision-cut in a factory? Storing carrots and boxes in your basement? Why not live in the basement...

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True enough!!!

The problem is....Products like RedGard are being marketed to DIY's as crack isolation membranes. DIY'S don't usually think about slab moisture or care about it unless there is a real obvious problem that has somehow come to their attention. Moisture in a slab and it's possible effects on subsequent floor coverings is an issue that is basically only widely known to professional installers. This is another case of putting some products into the hands of DIY's and not offering all the facts of potential dangers and failures if inadequate conditions aren't recognized and addressed.

Liquid waterproofing membranes can be great and easy products to use but is their use going to be the lessor of the evils in all cases? No, it's not!

The duct tape procedure doesn't even deserve the time it takes to comment about that technique. Just think about it. When crack isolation membranes are used to address only cracks and not entire planes it is recommended...

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Solutions for Basement Moisture Problems

Did you know that most basements start leaking water within 10 to 15 years?

The telltale signs of basement moisture are efflorescence ("white powder") and musty odors. Finishing the basement traps water vapor seeping through the concrete, which causes molds and musty odors in many basements. Rising basement air then spreads molds and radon gas through the house.

You are not alone! Did you know:

OVER 60% OF HOMES have a wet or damp basement. 1 IN 3 HOMES have mold and mildew growth 1 IN 6 HOMES have elevated levels of radon gas 2% OF HOMES have the toxic "black mold"

Be Proactive! Protect your basement remodeling investment by first sealing the walls and floor against water and vapor, molds, and radon.

How To Waste $1,000s on Basement Waterproofing

When trying to repair a wet basement or alleviate a damp one, you might get stuck in an endless cycle of waterproofing “fixes” that consume...

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Fibers, and Finishers, and Sealers! Oh My!

Water is a big deal. Without it, it’s nearly impossible to place and work concrete using traditional methods. With too much, concrete takes too long to set and is compromised in strength and durability. Adding water to the surface makes the slab easier to work and finish, but it increases the chances of surface defects down the line. Solomon Colors offers a variety of products to help manage this element of concrete and maximize the performance of every yard.

Good Made Better: How the UF500 Automated System Revolutionizes Secondary Fiber Reinforcement

Secondary reinforcing fibers can be a double-edged sword. They can control cracks and generally improve performance, but they can be time consuming, difficult, and even hazardous to add to the mix. Manually adding bags of fiber to the trucks slows batching, it is difficult to track, and exposes workers to risk of injury from...

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Grinding & Leveling

Grinding concrete eliminates raised trip hazards in sidewalks and other walkways.
If you have a business, the Canadians with Disabilities Act might even require you to grind down raised trip hazards. Concrete grinding can save you hundreds or thousands of dollars over a complete surface replacement.
With the right grinding equipment, it’s possible to take on just about any job, from sanding a small hump in the cement to excavating a 1” trench hundreds of feet long.

Floor Grinding Cement floors are never completely smooth and level. Cement slabs always have hard-to-see imperfections. A smooth, level surface is critical before installing tile, linoleum or engineered laminate flooring.
Professional concrete grinding contractors can make your floor level enough for any purpose, whether it’s tile or linoleum installation or polishing and staining the floor to a high sheen.
Here’s how the process works: Any high spot 1/8”...

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RadonSeal Cutting-Edge Products and Service Since 1997

Waterproofing or radon mitigation projects are not always simple but with a little know-how and the right advice, permanent do-it-yourself repairs can be accomplished relatively easily and with great savings. For the past 20 years we have been dedicated to offering our customers unbiased expertise, unparalleled service and our professional-quality, ready to use, concrete sealers, brick sealers, and concrete repair products.

Whether your intention is to dry out a damp basement, reduce radon levels, waterproof a brick chimney, prevent concrete dusting, or preserve the look of your outdoor pavers, our line of trusted, professional-grade penetrating concrete sealers will more than exceed your expectations! No messy mixing – our sealers are ready to apply on delivery. Superior to anything available in stores which sell film-forming sealers that will break down, peel, discolor, and most have to be reapplied...

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Efflorescence occurs with all concrete and is the most frequent problem that concrete contractors face with colored concrete. Owners don't care about “plain” concrete, but colored concrete is another matter. They complain that their contractor didn't give them the color they ordered, and sometimes they withhold payment. Efflorescence is caused when soluble salts and other water dispersible materials come to the surface of concrete and mortars. It's induced by low temperatures, moist conditions, condensation, rain, dew, and water added to the surface of fresh concrete to assist troweling. It can occur very soon after exposure to moist or cool conditions or gradually, especially when it comes from within the concrete or from the subgrade. Any material containing portland cement results in efflorescence. The most usual reaction occurs when calcium hydroxide (lime) formed in the hydration reaction of portland cement (approximately 140 pounds per cubic yard of concrete) is...

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Do you have any questions about this product? Call (888)355-6287, or email us.

Questions others have asked:

Hello I'm looking to see if this material is designed for going over a dirt floor basement? Thanks ken

Hi Ken, Thank you for your question. Yes, it designed to go over a dirt floor basement. Please look under the "Specifications" tab and you will see which Mil (thickness) is recommended for that application. Thabnk you, The Koffler Team

I need about 150-200 sq. ft. of a 12 mil. or higher barrier. Do you cut custom lengths or have any pieces left over for purchase?? Let me know, I'd be interested to buy it. thanks.

Hi Mike, Thank you for you question. Unfortunately we do not cut custom lengths or have any extra pieces for purchase. Thank you, The Koffler Team

Need to place this on dirt ground for underneath a porch. What do you recommend to fasten with? And assuming I should use 12 mil since it's covering dirt.

Hi Kathleen, ...

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