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CONCRETE SLAB
CHARACTERISTICS
Concrete is a mixture of Portland cement, water and aggregates.
The ratio of water-tocement is a critical factor in the overall
porosity of the slab. While the water/cement ratio of the concrete
mix has a direct impact on the final permeability of a finished
slab, the curing of the concrete has an important degree of influence
upon the ability of a slab to transmit moisture vapor. There is
a significant difference between moisture content and moisture
movement in concrete. Moisture (water) is a necessary and constructive
constituent of hardened
concrete. Movement of moisture in the form of vapor or liquid
may transport beneficial chemicals out of the concrete and transport
harmful chemicals in, substantially weakening the structure of
the concrete substrate. Porosity and permeability are key characteristics
of moisture movement. The concentration of moisture in building
materials often determines the extent of migration and the degree
of damage. The common sources of excessive building moisture are
rain, ground water, and condensation. Other causes of excessive
moisture
accumulation are building design defects and poor maintenance.
As a liquid (water) and a gas
(water vapor), moisture is constantly in motion:
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From warm to cold spaces in a pore -- these movements occur
when there is a greatdifference
in temperature and in relative humidity between the interior
and exterior.
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From fresh to salty conditions -- healthy concrete is extremely
alkaline and moisture movement is assisted by the availability
of soluble hydroxides in hardened concrete.
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From smaller pores to larger ones -- the higher the porosity
of a material, the more likely it will absorb moisture -- the
lower the water-cement ratio, the smaller the pores and the
stronger the cement.
MOISTURE MIGRATION
Moisture problems can be largely avoided by having adequate drainage,
by sealing cracks, and by grading soils so that they slope away
from the foundation. Placing a vapor retarder under the floor
slab hinders both vapor diffusion and capillary transport of soil
moisture through the foundation. Many of the vapor retarders placed
under buildings do not perform to their intended specifications
due to improper placement or intentional puncturing.
All building materials will have
a certain degree of humidity since vapor emission will go from
the concrete slab all the way to the ceiling. Placing STEP WARMFLOOR
heating elements on the concrete floor creates a natural barrier
of even and low temperature
stabilizing the difference between cold and warm.
Slabs that emit in excess of
the water tolerance will ultimately result in the failure of any
flooring material. Require a complete moisture and alkaline test
report prior to any installation to insure that the substrate
condition is in compliance with the floor covering.
SLAB
INSULATION
The insulation must be strong (high compressive strength) and
stiff (high foundation modulus) to avoid pavements to bend or
crack under eavy load and traffic. Consult manufacturer for deflection/load
characteristics and for maximum allowable live and dead load limits.
STEP WARMFLOOR is a strong, flexible, polymer element and can
reduce expansion and contraction by maintaining an even temperature
on the slab.
In
those regions where underlying soils are prone to frost action,
unheated building structures must be insulated beneath the entire
area of the floor, footings and beyond as required to adequately
protect against frost heave. In heated structures, insulation
is placed around and beyond the perimeter of the building to reduce
frost penetration, perimeter heat loss and moisture migration.
WATERPROOF
MEMBRANE
URA-SEAL. System is a new innovative waterproof membrane product
that utilizes Healthier Choice and Dow Chemical's mechanically
frothed closed cell polyurethane chemistry and technology. The
membrane is impervious to water damage and can be installed on
concrete slab floors on- or below-grade. A channel system is placed
to allow the escape of moisture migration and off gassing.
URA-SEAL System Installation Procedures
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Completely remove wax, paint, old adhesive and floor sealer.
If necessary use a concrete shot blaster to etch and properly
clean the concrete floor.
-
The surface must be dry and free from dust before starting the
installation.
- Following
the examples and diagram below, layout and apply channel tapes
that vent
to wall areas.
- At
intervals of approximately 20", apply a good quality 1"
wide duct tape across the
floor and approx. 2" up baseboards/walls on all sides.
- Tape runs shall not be placed closer than 12" from walls
and door openings.
- Cover the entire floor area with the squared pattern channel
tapes.
- Roll or press duct tape firmly to the floor to assure proper
bond.
-
Properly apply with a high-density paint roller approved aero-matic
vapor pressure lowering solvent free floor sealer over the entire
floor. Floor sealer must be dried/cured before applying adhesive.
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Apply tested, approved and warrantied aero-matic vapor pressure
lowering solvent free adhesive to the sealed floor area.
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After adhesive has reached a proper tack point, cut and remove
duct tape.
- CRI
104 and 105 or equivalent installation procedures must be followed.
- Overlap
and double cut all membrane seams being sure to cut paralleled
seams at least 6" away from channel tapes.
- Lay
woven polypropylene side of membrane into the adhesive.
- Roll/press
with a roller. A 100% adhesive transfer to the woven fabric
has to be attained to assure a proper bond to the floor.
-
After membrane is properly adhered to the floor, apply a small
bead of approved waterproof membrane seam sealer to all seams,
being sure to fill all seam gaps as necessary to assure a waterproof
joint.
-
After seam sealer has cured beyond the tack stage, roll/ press
with a roller.
- Use
only aero-matic vapor pressure lowering solvent free approved
adhesive between waterproof membrane and the primary floor.
NOTE:
The success or failure of the installed URA-SEAL System depends
on certified, trained installers that will follow the system installation
procedures and always use approved, tested and warrantied installation
products.
INSTALLATION GUIDELINES
Application
of STEP WARMFLOOR over STEP US2 Membrane
- Secure the STEP elements onto the STEP US2 Membrane.
- Cover the elements with a suitable floor covering.
- For installation guidelines, see Exterior Application, Wet Areas,
Tile, Resilient, Wood, Carpet and Carpet Cushion.
Application
of STEP WARMFLOOR using rigid foam insulation
Consult manufacturer for installation recommendations and instructions.
Extruded polystyrene foam insulation is combustible and should
be protected from flame and other high heat sources. It should
be installed with code-acceptable thermal barriers or used in
approved alternative constructions.
Installation
for new construction:
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As shown in the diagram below, Styrofoam*HI Insulation or equivalent
is laid in a configuration that allows for corresponding reduction
in foundation depth. The depth of the footing is governed by
the required load bearing capacity of the soil, not the frost
penetration.
-
Install US2 Membrane over the leveled gravel. This insulation/vapor
barrier superior puncture resistant membrane should be used
fabric side down.
- Pour
the concrete on polyethylene side of membrane. When concrete
is poured over an impermeable surface (foam or film), a low
water/cement ratio is recommended.
-
Allow the concrete to cure properly and for the humidity to
stabilize.
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Secure the STEP elements onto the slab.
- Cover
the elements with a suitable floor covering.
Installation
using furring strips:
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Apply 2 layers of Styrofoam Wallmate brand insulation or equivalent
flush on the slab.
- Use 1" x 3" furring strips as a nailing base for 3/4"
plywood underlayment.
- Secure the STEP elements over the rigid insulation.
- Install a suitable floor covering.
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