SECTION 03540

GYPSUM CEMENTITIOUS UNDERLAYMENT

RECOMMENDED SPECIFICATION FOR ORTECRETE® FLOOR UNDERLAYMENT IN
MULTIFAMILY HOUSING AFTER REMOVAL OF 1 1/2" (38 mm) LIGHTWEIGHT CONCRETE

PART 1   GENERAL

1.01     SUMMARY

A.   This is the recommended specification for Ortecrete Floor Underlayment in multifamily housing after removal of 1 1/2" (38 mm) lightweight concrete.

1.02       SECTION INCLUDES

A.   Ortecrete gypsum cement

B.   Maxxon Floor Primer

C.   Maxxon Overspray

D.   Underlayment Reinfo rcement mesh

1.03       QUALITY ASSURANCE

A.   Installer's Qualifications: Installation of Ortecrete shall be by an applicator authorized by the Maxxon Corporation using Maxxon approved mixing and pumping equipment.

1.04     DELIVERY, STORAGE AND HANDLING

A.   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.

1.05     SITE CONDITIONS

A.   Environmental Requirements: Before, during and after installation of Ortecrete, building interior shall be enclosed and maintained at a temperature above 50 degrees F (10 degrees C).

PART 2   PRODUCTS

2.01     MATERIALS

A.   Gypsum Cement: Floor underlayment Ortecrete gypsum cement as manufactured by the
Maxxon Corporation, Hamel , MN . All others must receive prior approval.

B.   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.

C.   Mix Water: Potable, free from impurities.

D.   Subfloor Primer: Maxxon Floor Primer

E.   Sealer: Maxxon Overspray

F.   Underlayment Re inforcement Mesh: Maxxon Plastic Net, plasterer's lath or Keydeck mesh (no minimum gauge).

2.02     MIX DESIGNS

A.   General Requirements: Mix proportions and methods shall be in strict accordance with product manufacturer recommendations.

PART 3   EXECUTION

3.01   PREPARATION

A.   Removal of Lightweight Concrete: The general contractor shall remove all the 1 1/2" (38 mm) lightweight concrete and felt paper from the subfloor.

B.   Condition of Subfloor: The general contractor shall remove, repair or replace all delaminated, deflective or damaged plywood.

C.   Cleaning of Subfloor: The general contractor shall clean subfloor of dirt, dust and other contaminating factors before underlayment re info rcement mesh is fastened down.

D.   Leak Prevention: Fill cracks and voids with a quick setting patching or caulking material where leakage of Ortecrete could occur.

E.   Install Underlayment Re info rcement: Layout and fasten across the entire floor area underlayment re info rcement mesh. Install Maxxon Plastic Net, plasterer's lath or Keydeck mesh by overlapping and mechanically fastening to the subfloor.

F.   Priming Subfloor: Prime the subfloor using the Maxxon Floor Primer. Priming instructions may vary according to the type of substrate, follow Maxxon Corporation's recommendations for dilution ratios and coverage rate.

G.   Expansion Joints: Allow joints to continue through the Ortecrete at the same width.

3.02   APPLICATION OF CEMENTITIOUS FLOORING

A.   Scheduling: Application of Ortecrete shall not begin until the building is enclosed, including roof, windows, doors and other fenestration. Schedule application of Ortecrete after installation of gypsum board work.

B.   Application: Place Ortecrete product 1 1/2 inch (38 mm) minimum over plywood subfloor. Spread and screed Ortecrete to a smooth surface. Except at authorized joints, place Ortecrete as continuously as possible until application is complete so that no Ortecrete product slurry is placed against Ortecrete product that has obtained its initial set.

C.   Drying: General Contractor shall provide continuous ventilation and adequate heat to rapidly remove moisture from the area until the Ortecrete is dry. General Contractor shall provide mechanical ventilation if necessary. Under the above conditions, for 1 1/2 inch (38 mm) thick Ortecrete, 10-14 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 10-14 days after pour.

3.03   PREPARATION FOR INSTALLATION OF GLUE DOWN FLOOR GOODS

A.   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.

B.   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.

3.04   FIELD QUALITY CONTROL

A.   Slump Test: Ortecrete 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.

B.   Field Samples: At least one set of 3 molded cube samples shall be taken from each day's pour during the Ortecrete 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.

3.05   PROTECTION

A.   Protection From Heavy Loads: During construction, place temporary wood planking over
Ortecrete wherever it will be subject to heavy wheeled or concentrated loads.

END OF SECTION