Recommended Specification For Dura-Cap® Floor Underlayment Over Precast Concrete Slabs
Summary
This is the recommended specification for Dura-Cap Floor Underlayment over precast concrete slabs.
Section Includes
- Dura-Cap gypsum cement
- Maxxon Floor Primer
- Maxxon Overspray
Quality Assurance
Installer's Qualifications: Installation of Dura-Cap 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 Dura-Cap, building interior shall be enclosed and maintained at a temperature above 50 degrees F (10 degrees C) and below 100 degrees F (37.7 degrees C) until structure and precast temperature are stabilized.
Products
Materials
Dura-Cap gypsum cement: Floor underlayment compound shall be Dura-Cap gypsum cement underlayment as manufactured by 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 Specification 101.
Mix Water: Potable, free from impurities.
Precast Primer: Maxxon Floor Primer
Sealer: Maxxon Overspray 74
Mix Designs
General Requirements: Dura-Cap mix proportions and methods shall be in strict accordance with product manufacturer recommendations.
Execution
Preparation
Condition and Cleaning of Precast: Precast shall be structurally sound. General Contractor shall clean precast to remove mud, oil, grease, and other contaminating factors before arrival of the Dura- Cap underlayment crew.
Leak Prevention: Fill cracks and voids with a quick setting caulk or patching material where leakage of Dura-Cap could occur.
Priming Precast: Prime precast using the Maxxon Floor Primer. Priming instructions vary according to the porosity of the precast, multiple coats may be necessary.
Expansion Joints: Allow joints to continue through the Dura-Cap at the same width.
Application of Self-Leveling Fooring
Scheduling: Application of Dura-Cap 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 Dura-Cap from 3” (76 mm) to featheredge. Spread and float Dura-Cap to a smooth surface. Except at authorized joints, place Dura-Cap as continuously as possible until application is complete so that no Dura-Cap slurry is placed against Dura-Cap product that has obtained its initial set.
Drying: General Contractor shall provide continuous ventilation and adequate heat to rapidly remove moisture from the area until the Dura-Cap is dry. General Contractor shall provide mechanical ventilation if necessary. Under the above conditions, for 3/4 inch (19 mm) thick Dura- Cap, 5-7 days is usually adequate 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: Dura-Cap 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 Dura-Cap application. Cubes shall be tested as recommended by the Maxxon Corporation in accordance with modified ASTM C 472. 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 Dura-Cap wherever it will be subject to heavy wheeled or concentrated loads.