Installation Guide

INSCT0816
11
CONCRETE APPLICATION GUIDELINES
Initial start up of the oor heating system must be delayed until the end of the
curing period (typically 28 days). Otherwise, the concrete adhesive properties
will be compromised, thus reducing the oor covering adhesion. Contact a
oor covering specialist to ensure proper adhesion.
Concrete layer thickness must be consistent with the manufacturer’s
recommendations, which are based on the type of installation as well as the
concrete specications. Furthermore, the concrete layer must entirely cover
the cable, but shall never exceed a maximum thickness of 1 inch (25.4 mm).
In order to maintain the spacing between cable runs longer than 6 feet (1.8 m)
and to prevent the cable from moving up to the surface during the application
of the self-leveling mortar, it is recommended to glue mounting brackets
upside down over the cable runs (in the middle) or to glue the cable directly
to the oor with hot glue.
N.B. Refer to section GETTING STARTED before proceeding to the
concrete covering.
SCRATCH COAT (METHOD RECOMMENDED BY STELPRO)
The scratch coat is a thin concrete layer in which the heating cable is
embedded. The concrete used can be either a polymer-modied mortar
meeting A118.4 (A) ANSI standards applied with a trowel, or a self-leveling
mortar poured over the heating cable. Subsequently, the oor covering can
be installed onto this concrete layer.
PRIMER APPLICATION
Before applying the scratch coat, check with the manufacturer whether the
specic concrete used (polymer-modied mortar meeting A118.4 (A) ANSI
standards or self-leveling mortar) requires the use of a primer. If a primer is
required, it should only be applied after the cables have been secured to the
suboor in order to reduce trafc over the primer.
APPLYING SCRATCH COAT ONTO THE HEATING CABLE
Once the cable installation has been completed and the primer has been
applied (if required), you must, in order to protect the cables and facilitate
eventual repairs, cover them with either a polymer-modied mortar meeting
A1184 (A) ANSI standards or a self-leveling mortar. Mix the concrete in
accordance with manufacturer instructions. The cable must be completely
covered by the concrete layer.
Self-leveling mortar
Although self-leveling mortar is by its very nature a self-leveling product, you
may have to use a trowel to level the corners of the room.
FLOOR COVERING INSTALLATION OVER THE SCRATCH COAT
Once the concrete is dry, you may proceed with the installation of your oor
covering. Ask the concrete manufacturer about the specic curing period of
the concrete used.
Lying tiles over the scratch coat
Given the large number of “on/off” cycles dictated by the thermostat, only a
highly exible polymer-modied mortar meeting A118.4(A) ANSI standards
may be used to secure the tiles onto the scratch coat. The polymers comprised
in this type of mortar contribute to its strength and exibility ensuring long term
efciency.
Grouting can begin no sooner than 24 hours after the installation has been
completed. Either use a polymer-modied grout (with or without sand)
meeting A118.6(A) or A118.7(A) ANSI standards or an epoxy grout meeting
A118.3 ANSI standards (see FIGURE 18 and FIGURE 20).
self-leveling mortar
heating cable
polymer modified mortar mixed with a liquid
additive meeting A118.4 (A) ANSI standards
polymer modified grout (with or without sand)
meeting A118.6 (A) or A118.7 (A) ANSI standards
floor covering
epoxy grout meeting
A118.3 ANSI
standards
or
subfloor
FIGURE 18
TTMAC: Terrazzo, Tile & Marble Association of Canada
ANSI: American National Standards Institute
* For each of these concrete products, you must check with the manufacturer to ensure compatibility of their product with oor heating
systems and your suboor type. Also, the product must be applied in accordance with their recommendations.
** N/A: Standard not available. Check with the manufacturer to ensure product compatibility with the oor heating system.
*** A polymer-modied mortar can be obtained using one of these two methods: by adding water to a polymer-modied mortar or by adding a
liquid additive containing polymers to a non-polymer-modied mortar.
CONCRETE SELECTOR TABLE*
USAGE
SPECIFIC CONCRETE PRODUCTS
CABLE EMBEDDING
(SCRATCH COAT
METHOD ONLY)
CERAMIC TILE
ADHESIVE
GROUT STANDARDS
Self-leveling mortar YES NO NO N/A**
Polymer-modied mortar*** YES YES NO ANSI A118.4 (A)
Polymer-modied grout (with or without sand) NO NO YES ANSI A118.6 (A) or A118.7 (A)
Epoxy grout NO NO YES ANSI A118.3
CONCRETE APPLICATION
The heating cable must always be embedded in concrete or covered by a thin concrete layer. Two methods are available: SCRATCH COAT (method
recommended by STELPRO) as well as THIN SET METHOD (alternative method for experienced tile setters only). Please refer to the CONCRETE SELECTOR
TABLE on following page to nd out the type of concrete recommended for each method.