LATICRETE® International > Architects > Technical Services > FAQ > Planning a Job

Architects Distributors Dealers Contractors Homeowners International

Architects » Technical Services » FAQ » Planning a Job » Radiant Heat Systems

For answers to all your planning questions click on the specific product area. Can't find your answer? Call 1.800.243.4788 x235 for LATICRETE Technical Services, or, email us at technicalservices@laticrete.com

For answers to all your planning questions click on the specific product category below.

Mat and Tile Installations

What substrates can I install LATICRETE^® Floor HEAT onto?

LATICRETE^® Floor HEAT can be laid directly over properly prepared concrete, exterior glue plywood, cement backer board, fiber cement underlayment, existing ceramic tile/stone, existing ceramic tile and stone, or cement mortar beds.

Can I trowel directly over the mat and set tile immediately? *

Yes. Simply key the mortar into the mat and substrate using the flat side of a trowel, or a rubber float, to apply a smooth skim coat of a latex or polymer fortified thin-set or medium bed mortar (e.g. LATICRETE 254 Platinum or LATICRETE 220 Marble & Granite Mortar mixed with LATICRETE 333 Super Flexible Additive) over LATICRETE Floor HEAT mat. Make sure to use enough mortar to cover and protect the heating element wire in its entirety. Trowel additional thin-set mortar and set the tile or stone in one step.

How do I install tile onto a plywood floor with a hydronic radiant heat system? *

Make sure that the floor meets deflection and construction standards (consult TDS 152 at www.laticrete.com) and tape all board joints. Apply LATICRETE Blue 92 Anti-Fracture Membrane to the plywood surface. Install the tile or stone using LATICRETE 333 Super Flexible Additive mixed with LATICRETE 317. Grout using LATICRETE SpectraLOCK^® PRO Grout, LATICRETE PermaColor^TM Grout, or LATICRETE 1500 Sanded Grout gauged with LATICRETE 1776 Grout Enhancer.

Can I pour self-leveling underlayment over LATICRETE Floor HEAT? *

Yes. For installation over concrete or cement mortar beds - first prime the substrate with LATICRETE Admix and Primer (or required primer based on underlayment) and allow to dry to a clear film (2-3 hours at 70°F [21°C]). Lay the LATICRETE Floor HEAT mat onto the primed surface, mix LATICRETE 86 LatiLevel™, LATICRETE 84 LatiLevel, DRYTEK self-leveling underlayment(e.g. DRYTEK 4000, DRYTEK 7200, etc...), or other self-leveling underlayment and pour over entire field. Ensure that LATICRETE Floor HEAT mat is completely encapsulated by self-leveling underlayment and allow to dry.

For installation over exterior glue plywood, cement backer board or fiber cement underlayment – prime the substrate surface with LATICRETE Admix and Primer (or required primer based on underlayment) and allow to dry for 2 – 3 hours. Lay the LATICRETE Floor HEAT mat onto the primed surface and staple whit emesh (not blue wires) to the floor. Mix LATICRETE 86 LatiLevel, LATICRETE 84 LatiLevel, DRYTEK self-leveling underlayment, or other self-leveling underlayment and pour over entire field. Ensure that LATICRETE Floor HEAT mat is completely encapsulated by selfleveling underlayment and allow to dry.

For installation over existing ceramic tile or stone – skim coat existing tile or stone installation with a rapid, polymer fortified thin-set mortar (e.g. LATICRETE 254R Platinum Rapid) and allow to dry for 2 -4 hours. Prime the hardened skim coat with LATICRETE Admix and Primer (or required primer based on underlayment) and allow to dry to a clear film (2-3 hours at 70°F [21°C]). Lay the LATICRETE Floor HEAT mat onto the primed surface, mix LATICRETE 86 LatiLevel, LATICRETE 84 LatiLevel, DRYTEK self-leveling underlayment, or other self-leveling underlayment and pour over entire field. Ensure that LATICRETE Floor HEAT mat is completely encapsulated by self-leveling underlayment and allow to dry.

Can I skim coat the LATICRETE Floor HEAT mat into place and then set tile at a later time? *

Yes. Skim coat the LATICRETE Floor HEAT mat with a polymer-fortified thin-set (e.g. LATICRETE 254 Platinum) using the flat side of a trowel or a rubber float and allow to dry. Tile can be installed directly to the skim coat the next day.

What LATICRETE mortars can be used to install LATICRETE Floor HEAT?

Any LATICRETE polymer-fortified (e.g. LATICRETE 254 Platinum) or medium bed mortar (LATICRETE 255 MultiMax^TM, or, LATICRETE 220 Marble & Granite Mortar mixed with LATICRETE 333 Super Flexible Additive) can be used to install LATICRETE Floor HEAT mat. Please refer www.laticrete.com to make ensure that the thin-set is compatible with your substrate.

What floor finishes can I install over LATICRETE Floor HEAT?

LATICRETE Floor HEAT is specifically designed for the installation of tile and stone only.

Can LATICRETE^® Floor HEAT be used in a shower or for exterior applications?

No. LATICRETE Floor HEAT is not designed to be used in showers or any exterior application.

Can LATICRETE Floor HEAT be stapled to a suitably constructed (per Tile Council of North America) exterior glue plywood substrate?

Yes. However, be sure to only staple the white mesh and not the blue wire.

How long will it take to warm the floor with LATICRETE Floor HEAT?

Each installation will vary due to several factors; thickness of the tile or stone, type of substrate, size of tile, and ambient temperature will all play roles in how fast the floor warms. A good rule of thumb is 30 – 45 minutes on average.

Can I use a waterproofing or anti-fracture membrane in conjunction with LATICRETE Floor HEAT?

Yes. LATICRETE 9235 Waterproofing Membrane and LATICRETE Blue 92 Anti-Fracture Membrane can both be installed on top of the LATICRETE polymer fortified thin-set, or LATICRETE 86 LatiLevel™, prior to installation of tile. These membranes can withstand temperatures up to 280°F (138°C).

How do I layout the LATICRETE Floor HEAT prior to installation?

You can visit http://www.laticrete.com/architects/products/floor_warming/room_design_tool.aspx, contact your local LATICRETE distributor or call LATICRETE Technical Services at 1.800.243.4788 x235 for more information.

Is LATICRETE Floor HEAT covered by any LATICRETE Warranty?

Yes. LATICRETE Floor HEAT is provided for in the LATICRETE Lifetime Residential Warranty and LATICRETE 10 Year System Warranty as a component of a complete product system. For further information on LATICRETE Warranties please visit our website at www.laticrete.com or contact LATICRETE Technical Services at 1.800.243.4788 x235.

When can I turn my LATICRETE Floor HEAT on?

LATICRETE Floor HEAT mat should not be turned on until the entire tile installation (including grout) has had a chance to fully cure (typically 48 hours at 70°F [21°C]). Cooler temperatures require longer cure time.

Electrical

Should I have a professional electrician hook up my LATICRETE Floor HEAT to the thermostat and wiring? *

Yes. By most building codes, only a professional electrician should make all connections regarding any electrical wiring. Failure to have electrical connections performed by a licensed electrician will void the LATICRETE Warranty and, quite possibly, can void any homeowner’s insurance.

What electrical requirements does LATICRETE Floor HEAT need? *

LATICRETE Floor HEAT requires a minimum 20 amp dedicated circuit and must be installed by a professional electrician.

How much does LATICRETE^® Floor HEAT cost to operate?

Consider an average kitchen lighting fixture, containing three 75 watt light bulbs, uses 225 watts of electricity. A 15 ft² mat will draw the same wattage, and therefore cost the same, as the lighting fixture. With the programmable thermostat, optimum efficiency is achieved as the mat heats up and automatically turns off. A good estimate is that the LATICRETE^® Floor HEAT will cost pennies per day when programmed to turn on and off periodically.

Is LATICRETE Floor HEAT available in a 240 Volt as well as a 120 Volt configuration?

Yes. LATICRETE Floor HEAT is available in both 120 Volt and 240 Volt configurations. It is essential that the voltage of the LATICRETE Floor HEAT components you purchase matches the electrical supply of your house or building. The LATICRETE Floor HEAT Thermostat is designed for use with both 120 and 240 V.

How many LATICRETE Floor HEAT mats can I install for one thermostat? *

For a majority of installations the number would be three. However, depending upon the size of the mats, two may be the maximum. Please consult LATICRETE Technical Services at 1.800.243.4788 x235, or contact your professional electrician for more information.

Can I join two (2) mats together by connecting their wires? *

No. Never should any 2 LATICRETE Floor HEAT mats be directly connected together. Applications requiring more than one mat should be wired by a professional electrician and joined in a junction box or relay, then wired into the same thermostat.

Can I cut the blue heating element (wire) if I have too much left over?

No. The blue heating element (wire) should not be cut under any circumstances. Depending upon the amount of mat left over, you can cut the white mesh in between the blue wire and simply string the remaining wire along the wall (being careful not to cross the wires) to hide the excess. Excess wire and mat should never be installed within a wall, folded over, installed vertically or placed under any appliance or fixture (e.g. cabinets, toilets, etc…). Failure to comply will void any warranty or claims. If possible purchase the correct size mat to fit the area to be heated.

What happens if a wire is cut, frayed or chipped?

Repair kits are available. Please contact LATICRETE Technical Services at 1.800.243.4788 x235 to obtain a kit and instructions on performing repairs.

Can I lay one blue heating element (wire) over another? *

No. The blue heating elements (wire) should not be laid on top of each other or make contact in any way. Please consult with a licensed electrician or LATICRETE Technical Services, at 1.800.243.4788 x235 for more information.

* Please refer to DS 605.9 “LATICRETE® Floor HEAT Installation Instructions” for more.
information.

[RIGHTPANE]

LATICRETE, LATAPOXY, SPECTRALOCK and the logo are Registered Trademarks of LATICRETE International, Inc.