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Want an opinion on sealant for cement and health impacts of offgassing

Christopherpcampbell | Posted in General Questions on

I am looking at sealing the cement slab-on-grade floor and below-grade sections of poured cement walls. Interested in any adverse health impact for living space.

Does anyone have particular product recommendations? I am particularly looking at Enduroseal and would like any opinions about this product from an environmental/health standpoint for living space. The product offers that it penetrates into the concrete to block capillary water movement inward, and has no offgassing.

I’d like to hear from the discriminating minds at Green Building Advisor.


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  1. Expert Member

    I have had good luck with Xypex, which is another crystalline waterproofing product.
    As far as health effects, here is an excerpt from their FAQ:

    Xypex toxic? READ
    No. Xypex contains no volatile organic carriers (VOC) and can be applied safely in enclosed surroundings. Xypex is approved by numerous health and waterworks departments around the world for use on structures that contain potable water or foodstuffs. A few of these agencies are:

    NSF International
    Swiss Federal Department of Health
    Japan Food Research Laboratories
    United Kingdom (DWI) Drinking Water Inspectorate
    Australian Water Quality Centre
    Singapore Institute of Standards and Industrial Research
    France Research Centre for the Control of Water
    Czech Republic Health Institute & Centre for Drinking Water

  2. Expert Member
    Dana Dorsett | | #2

    Enduroseal makes a dozen different concrete sealers, most of which are siloxane (silcone-plasticizer) based, with various alcohols acting as solvents, which is one fairly common approach, with many vendors. After the alcohols have dissipated (probably less than a week), most of the outgassing will be very low levels of siloxanes, ammonia, and amines, all materials with fairly low human toxicity. There are MSDS sheets available for each individual product, and you can look up the toxicity and volatility of the primary components.

    So, which exact product in their extensive lineup were you looking at?

    Their website makes a lot of noise about being a "vapor barrier", but they do not provide ASTM E96 test performance data on representative samples of concrete treated with their stuff. Most sealears are primarily capillary draw inhibitors, which will reduce the moisture flow of liquid and adsorb through the material, but isn't a true vapor barrier. The Enduroseal website also makes a lot of unsubstantiated & dubious claims about the performance / failures of poly vapor barriers under slabs too, claiming that punctures and soil settling under the slab causes puddles to form on the top side of the poly, and that poly becomes brittle & flaky over time, etc. Poly sheeting buried in dark damp soil has a lifespan of centuries, even if the same material becomes brittle and falls apart in a handful of years when exposed to the UV spectrum of sunlight. Concrete poured atop poly sheeting has a pretty good bond with the poly- a tighter bond than with (code required in most locations) clean gravel under the poly, and even sink-pockets form in the soil under the vapor barrier, it stays stuck to the concrete. The myriad micro-punctures and tears that may or may not be there have almost no effect on it's vapor retardency (since the total cross section of all those holes are at most a few square inches), and unlike concrete treated with sealers, cracks that form in concrete poured on a substrate so unstable that those sink-pockets form are still sealed by the flexible plastic sheeting.

    And unlike sealers, there are ATSM E86 performance numbers to look at with plastic sheeting.

  3. Christopherpcampbell | | #3

    Thank you, Dana.

    So I am convinced about using a polyethylene vapor barrier based on your arguments that it would not create beading.

    But I thought to also use a sealant. 1) Does that seem ok to you?

    I have not considered all the Endurseal products, but was looking at their Hydrolock Kit (

    Malcom above recomends Xypex.

    2) Do you have a product you recommend or a way to compare these above two?

    thanks again.

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