LEVELROCK Brand Floor
Underlayment
Technical Bulletin 001
TOPIC
Water Exposure
PUBLISHED
Fall 2001 |
NOTE: This page is formatted to print out as a USG LEVELROCK Brand
Floor Underlayment Technical Bulletin. The print format differs slightly from
Web page format.
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The
Effect of Water Exposure on Gyspum Underlayment
LEVELROCK Brand
Floor Underlayments - 2500,3500,4500 and RH (Radiant Heat) are specially
formulated binders that are mixed by USG licensed applicators with sand and
water in the field to pour floor underlayments. The specially formulated
binders consist of gypsum, Portland cement, and other additives. Since gypsum
is the primary component of the binders, it is commonly referred to as "gypsum
cement underlayments".
Pure gypsum casts lose strength and become soft
when exposed to water. But, upon drying, the cast regains 90-95% of its
original dry strength and hardness. Gypsum floor underlayments also exhibit
similar behavior. Gypsum underlayments can be and are being successfully used
in areas that only see occasional water exposure and areas that have a chance
to dry out after such occasional exposures (i.e. the overflow of a bathtub).
The product does not swell or shrink due to this occasional exposure and thus
will not result in cracking or other deterioration of floor coverings used over
them. Furthermore, the higher densities exhibited by LEVELROCK® Brand
Floor Underlayments help retard the intrusion of water into the underlayment
matrix. Thus, the occasional water exposure and subsequent drying out of the
product does not cause any long term degradation of strength or stiffness.
However, gypsum floor underlayments are not recommended for use in
areas subject to prolonged exposure to standing water - for instance, in gang
showers, saunas, hot tub decks, swimming pools etc.
If you have
specific questions on the use of LEVELROCK Brand Floor Underlayment products,
please call 1-800-USG-4YOU and we will be glad to help you in deciding if your
application is suitable.
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