Recommended Specification for Therma-Floor® Underlayment As the Heat Mass for Radiant Floor Heating
Summary
This is the recommended specification for Therma-Floor Underlayment as the heat mass for radiant floor heating.
Section Includes
- Therma-Floor gypsum
- Maxxon Floor Primer
- Maxxon Overspray
- Maxxon Set Modifier
Quality Assurance
Installer's Qualifications: Installation of Therma-Floor shall be by an applicator authorized by the Maxxon Corporation using Maxxon approved mixing and pumping equipment.
Delivery, Storage and Handling
General Requirements: Materials shall be delivered in their original, unopened packages, and protected from exposure to the elements. Damaged or deteriorated materials shall be removed from the premises.
Site Conditions
Environmental Requirements: Before, during and after installation of Therma-Floor, building interior shall be enclosed and maintained at a temperature above 50 degrees F (10 degrees C).
Products
Materials
Gypsum Cement: Floor underlayment Therma-Floor gypsum cement as manufactured by the Maxxon Corporation, Hamel, MN. All others must receive prior approval.
Sand Aggregate: Sand shall be 1/8 inch (3 mm) or less, washed masonry or plaster sand, meeting requirements of Maxxon Corporation Sand Specifications 101.
Mix Water: Potable, free from impurities.
Subfloor Primer: Maxxon Floor Primer
Sealer: Maxxon Overspray
Gypsum Cement Set-Time Accelerator: Maxxon Set Modifier
Mix Designs
General Requirements: Mix proportions and methods shall be in strict accordance with product manufacturer recommendations.
Execution
Preparation
Condition and Cleaning of Subfloor: Subfloor shall be structurally sound. General Contractor
shall clean subfloor to remove mud, oil, grease, and other contaminating factors before the arrival of
the Therma-Floor underlayment crew.
Leak Prevention: Fill cracks and voids with a quick setting patching or caulking material where
leakage of Therma-Floor could occur.
Priming Subfloor: Prime the subfloor using the Maxxon Floor Primer. Priming instructions may
vary according to the type of substrate, multiple coats may be necessary.
Expansion Joints: Allow joints to continue through the Therma-Floor at the same width.
APPLICATION OF CEMENTITIOUS FLOORING
Scheduling: Application of Therma-Floor shall not begin until the building is enclosed, including
roof, windows, doors and other fenestration. Install after drywall installation unless tenant finish
requirements identify partitioning after the pour.
Application: Place the Therma-Floor heat mass in a two pour application. Install the first lift
(pour) to the top of the tubing or cable, then allow to set-up. Maxxon Set Modifier may be used to
accelerate the set-time of the first lift per Maxxon Corporation's recommendations. Install the
second lift 3/4 inch (19 mm) above the first lift. Spread and screed Therma-Floor to a smooth
surface. The Therma-Floor minimum thickness over radiant heat systems is 3/4 inch
(19 mm) over the top of the tubes or cables.
Drying: General Contractor shall provide continuous ventilation and adequate heat to rapidly
remove moisture from the Therma-Floor until it is dry. General Contractor shall provide
mechanical ventilation if necessary. The radiant heat system can be started after the Therma-Floor
sets up to accelerate the drying time. To test for dryness, tape a 24 inch by 24 inch (609 mm by
609 mm) section of plastic or high density rubber mat to the surface of the underlayment. After 48-
72 hours, if no condensation occurs, the underlayment shall be considered dry. Perform dryness
test 5-7 days after pour.
PREPARATION FOR INSTALLATION OF GLUE DOWN FLOOR GOODS
Sealing: Seal all areas that receive glue down floor goods with Maxxon Overspray according to the
Maxxon Corporation's specifications. Any floor areas where the surface has been damaged shall
be cleaned and sealed regardless of floor covering to be used. Where floor goods manufacturers
require special adhesive or installation systems, their requirements supersede these
recommendations.
Floor Goods Procedures: See the Maxxon Corporation's "Procedures for Attaching Finished
Floor Goods to Maxxon Underlayments" brochure for guidelines for installing finished floor
goods. This procedure is not a warranty and is to be used as a guideline only.
FIELD QUALITY CONTROL
Slump Test: Therma-Floor mix shall be tested for slump as it's being pumped using a 2 inch by 4
inch (50 mm by 101 mm) cylinder resulting in a patty size of 8 inches (203 mm) plus or minus 1
inch (25 mm) diameter.
Field Samples: At least one set of 3 molded cube samples shall be taken from each day's pour
during the Therma-Floor application. Cubes shall be tested as recommended by the Maxxon
Corporation in accordance with modified ASTM C472. Test results shall be available to architect
and/or contractor upon request from applicator.
Protection
Protection From Heavy Loads: During construction, place temporary wood planking over Therma-
Floor wherever it will be subject to heavy wheeled or concentrated loads.