PRESWITT NON-COMBUSTIBLE RAINSCREEN

THERMAL AND MOISTURE PROTECTION
Division 7

EXTERIOR INSULATION AND FINISH SYSTEM (Mineral Wool)
Section 07240

PART 1 GENERAL

1.1 DESCRIPTION

.1 Work included: The work described in this section includes the supply and installation of the Exterior Insulation and Finish System, as indicated on the drawings and as specified..

.2 Related Work Under Other Sections:

STEEL STUDS AND FURRING:

Section ___________________________

EXTERIOR GYPSUM SHEATHING BOARD:

Section ___________________________

SEALANTS:

Section: __________________________

(See Note 3.)

1.2 QUALIFICATIONS

.1 The Exterior Insulation and Finish System shall be installed by a contractor approved and certified by the system manufacturer. Certification must be in force at the time the project is bid and contracted for.

1.3 SUBMITTALS

.1 Submit to the architect, for approval, duplicate samples of Finish Coating of color and texture selected by the architect. Samples shall be made by applicator utilizing tools, materials, and techniques proposed for installation.

.2 Obtain architect's approval of samples before ordering materials and proceeding with work.

1.4 PRODUCT DELIVERY, STORAGE AND HANDLING

.1 Store packaged materials in original containers with manufacturer' seals and labels intact, with each production lot identified by batch number. All lots with same batch number shall be stored together.

.2 Prevent damage to materials during handling and storage. Keep materials under cover and free from dampness.

.3 Store products in a cool, dry place out of direct sunlight, protected from the elements and from damage.

.4 System materials shall be stored at a temperature of not less than 5°C (40°F).

1.5 JOB CONDITIONS

.1 Ambient temperature must be no less than 5°C (40°F) during installation and until the Adhesive and Coatings are dry. (Minimum 24 hours).

.2 Construct proper free-standing scaffolds 460mm (18") from the wall surface to allow continuous uninterrupted application.

1.6 PROTECTION

.1 Protect adjacent areas from damage resulting from the installation of the system. All finish work shall be protected at the end of the day or completion of a section.

.2 Sections of the work must be protected from adverse weather conditions during the application and until the Coatings are dry.

PART 2 PRODUCTS

2.1 MATERIALS

The System shall be as manufactured and supplied by Preswitt Manufacturing Ltd., and comprised of a Reinforced Barrier Membrane, Insulation Board, a Reinforced Basecoat, and Acrylic Finish.

.1 Barrier Membrane: Shall be Preswitt M.P. Flexcoat.

.2 Insulation: Shall be Preswitt Mineral Wool Board with a nominal density of 8 lbs/cu. ft. Thickness shall be as indicated on the drawings.

.3 Adhesive Compound: Shall be Preswitt Adhesive Compound.

.4 Reinforcing Fabric: Shall be a balanced, opeanweave glassfibre fabric, treated for compatibility with the system materials. Fabric shall be supplied by Preswitt Manufacturing Ltd.

.5 Heavy Duty Reinforcing Fabric: Shall be balanced, openweave glassfibre fabric treated for compatibility with the system materials and used in high impact areas only. Fabric shall be supplied by Preswitt Manufacturing Ltd.

.6 Basecoat: Shall be Preswitt N.C. Basecoat in 25 kilo bags.

.7 Portland Cement: Type 10 Normal Portland cement conforming to CSA A5-1977 or Type 1,1-11, or 11 meeting ASTM C150.

.8 Mechanical Fasteners: If required, shall be as recommended by Preswitt Manufacturing Ltd. and approved by the project engineer.

.9 Primer: Shall be Preswitt Acrylic Superbond reduced 50/50 with water before application.

10. Angle trim at base of wall sections as required.

2.2 MIXING AND PREPARATION

.1 Adhesive Compound: Drill-mix with Portland cement in a ratio of 1:1 by weight.

.2 Basecoat: Add 6 liters of water to each 25 kilo bag of N.C. Basecoat and mix to a trowelable consistency.

.3 M.P. Flexcoat: Drill-mix with Portland cement in a ratio of 1:1 by weight.

PART 3 EXECUTION

3.1 INSPECTION

.1 Before commencing ensure that environmental and site conditions are suitable for the installation of the system.

.2 All areas to receive the system shall be sound, flat, even and free from irregularities.

.3 The substrate shall be a type approved by Preswitt Manufacturing Ltd.

.4 Where exterior gypsum sheathing is the specified substrate, ensure that it meets the required standard, is clean, dry, properly fastened and shows no sign of deterioration or defects.

.5 Wall surfaces shall be free of ice and frost.

.6 Ensure that all surfaces are free from loose particles, foreign materials, form oil and traces of any other releasing agents.

.7 Any discrepancies shall be reported to the architect or general contractor, and rectified before the work proceeds. Commencement of work indicates acceptance of conditions.

3.2 INSTALLATION

.1 Barrier Lamina: Apply 2mm (1/12") of the M.P. Flexcoat compound to the surface of the substrate. The size of a convenient section to be prepared at one time will depend on ambient temperatures and available manpower.

Precut the Mesh into workable pieces and apply with the concave side to the wall. Trowel the Mesh into the wet flexcoat compound, stroking from the center of the fabric towards the edges to work out the wrinkles. Lap Mesh a minimum of 64mm (2½").

The Mesh must be completely enclosed with no pattern remaining visible. Apply a skim coat of the compound, when required, to ensure complete encapsulation of the Mesh.

.2 At locations designated on drawings, install angle trim at base of wall sections with approved fasteners.

.3 Insulation: Using a 3/8" notched trowel apply the Adhesive compound to the wall surface in a vertical manner. Only apply the Adhesive to small managable areas to prevent the Adhesive from skinning over.

Press and secure the Insulation Board vertically onto the wall surface; ensure solid contact. Boards shall be placed from a level baseline with all joints butted tightly. Boards shall be flush and the insulation wall surface left flat and even. Mechanical fasteners, if required, will be spaced as directed by the engineer.All edges at penetrations must be backwrapped.

.4 Basecoat: Apply 2mm (1/12") of the Basecoat to the surface of the substrate. The size of a convenient section to be prepared at one time depends on ambient temperatures and available manpower.

Precut the Mesh into workable pieces and apply with the concave side to the wall. Trowel the Mesh into the wet Basecoat, stroking from the center of the fabric towards the edges to work out the wrinkles. Lap Mesh a minimum of 64mm (2½").The Mesh must be completely enclosed with no pattern remaining visible. Apply a skim coat of the compound, when required, to ensure complete encapsulation of the Mesh.

For high impact areas Heavy Duty Reinforcing Fabric shall be embedded in a Basecoat layer in a similar manner; the fabric shall be butt-jointed, with no laps, and allowed to dry for a least 24 hours. This shall be done prior to installing the standard fabric reinforced Basecoat. Both reinforced Basecoats are necessary for high impact areas.

Examine the surface and smooth out all rough spots, irregularities, ridges, etc. to prevent imperfections telegraphing through to the Finish Coat. Roll or brush apply a liberal coat of primer over the base coat, just prior to applying the Finish Coat. Ideally the primer should still be tacky.

5.Acrylic Finish: Remove the lid from the pail and stir the material to ensure dispersion of the solids that may have separated during shipping or storage. Keep stirring to a minimum to prevent air entrainment. A small quantity of potable water (1 cup) can be added, if required, to obtain a smooth workable consistency.

Using a steel trowel, evenly apply a coat of material. Use a plastic or steel float to achieve the desired texture. Maintain a wet edge: working to a dry edge will result in unsightly joints.

.6 Installation of the Exterior Insulation and Finish System shall be done in strict accordance with the contract documents, and the manufacturer's written instructions. The finished work shall match approved samples, be uniform in color, texture and be free from defects detrimental to appearance and performance.

SPECIFICATION NOTES

1. This guide specification is basic and must be adapted to suit the requirements of individual projects. Consult the manufacturer for specific recommendations.

2. This guide specification is prepared in accordance with Construction Specifications three part section format and should be included under Division 7 - Thermal and Moisture Protection as Section 07240, in accordance with CSC/CSI Master Format for specifications.

3. Insert list of related work specified in other Divisions, such as steel studs, exterior gypsum sheathing, sealants, flashings, etc. Sealant compounds should be compatible with Preswitt Wall System components. Insert also the appropriate section number.

4. The architect will be responsible for the building envelope design including the preparation of details showing how Preswitt Exterior Rainscreen Insulation System will interface with other exterior building components such as windows, doors and flashings.

5.. The owner will engage a qualified professional engineer to determine, and prepare drawings of, the compartment layout with sized vent openings required for air-pressure equalization of the building envelope design.

6. An independent building envelope inspection agency, acceptable to the local building code authority, shall be retained by the owner to approve the building envelope design including details and use of materials. This agency shall provide site supervision to ensure that the system is installed according to the manufacturer's application instructions.