09212_en.doc

SECTION 09212

EXTERIOR STUCCO

PART 1 - GENERAL

1.1

APPLICABLE PUBLICATIONS

The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by the basic designation only.

ITALIAN Laws

R.D. 2231 dated 16 Nov.1939 Norms for Acceptance of Limes.

D.M. dated 3 June 1968

New Norms for Acceptance Requirements and Test Methods on Cements.

Decree of Ministry of Public Works, dated 31 August 1972 Norms for Acceptance Requirements of Cement Agglomerates and Hydraulic Limes.

Italian National Institute for the Unification of Standards (UNI) Publications

UNI 2332-1

(1979) Test Sieves. Test Sieves and Relevant Receivers and Lids. Dimensions and Tolerances.

ITALIAN/EUROPEAN HARMONIZATION STANDARDS (UNI EN)(UNI ENV)(UNI EN ISO)

UNI ENV 413-1

(1994) Masonry Cement - Part 1: Specification.

UNI EN 459-1

(2002) Building Lime - Part 1: Definitions, Specifications and Conformity Criteria.

UNI EN 459-2

(2002) Building Lime - Part 2: Test Methods.

UNI EN 932-1

(1998) Tests for General Properties of

Aggregates - Part 1: Methods for Sampling.

UNI EN 932-3

(1998) Tests of General Properties of Aggregates - Part 3: Procedure and Terminology for Simplified Petrographic Description.

1.2

SUBMITTALS

1.2.1 Manufacturer's Catalog Data

Submit complete descriptive literature for stucco components. Clearly mark the data to indicate which type, or item the Contractor intends to provide. Provide sufficient data to show conformance to specified requirements. Include manufacturer’s name, address and phone number.

1.3

DELIVERY, STORAGE AND HANDLING

Deliver stucco aggregates to work site in unbroken bags or in their approved containers, plainly marked and labeled with manufacturers' names and brands. Store in dry, well ventilated and weathertight sheds or enclosures. Protect materials from direct contact with the ground. Handle materials with care to avoid damage.

1.4

ENVIRONMENTAL CONDITIONS

Do not apply stucco when the air temperature is below 4.5oC and falling. Work will not be permitted with or on frozen materials.

PART 2 - PRODUCTS

2.1

MATERIALS FOR STUCCO

2.1.1 Portland Cement

Portland cement shall conform to the requirements of D.M. dated 3 June 1968, and UNI ENV 413-1. Portland cement for the finish coat shall be white or light gray in color, as determined by the Contracting Officer’s Technical Representative. One brand shall be used throughout the work.

2.1.2 Hydrated Lime

Hydrated lime shall be of type commercially available and shall conform to the requirements of R.D. 2231 dated 16 November 1939, UNI EN 459-1 and UNI EN 459-2.

2.1.3 Nails and Staples

Nails for attaching reinforcement over masonry or concrete surfaces shall be large-head galvanized nails with an approved furring device not less than 6 mm in thickness between the reinforcement and the backing.

2.1.4 Metal Lath

Reinforcement shall be expanded metal diamond mesh lath, applied over joints between masonry and concrete surface. Expanded metal diamond lath shall be galvanized type having no stiffening ribs or other projections and having large openings. The metal shall be low carbon steel or copper steel and the lath shall be formed by slitting and then expanding sheets of steel. The width of the strands in the metal lath shall not be less than 1.3 mm and weighing 1 kg/m2. The maximum length of strands shall be 9 cm and the maximum area of any single opening shall be 26 sq mm.

2.1.5 Sand

Sand shall be clean, hard, free of loam, silt, or other impurities, and well graded in accordance with UNI 2332-1, UNI EN 932-1 and UNI EN 932-3.

2.1.6 Water Repellent

Shall be stearate or oleate of ammonium, sodium, or calcium in either powder, liquid or paste; or a commercially manufactured product approved by the Contracting Officer’s Technical Representative.

2.1.7 Water

Water shall be clean and free from injurious amounts of oil, alkali, acids, soluble salts and organic impurities.

2.1.8 Manufacturer

Acceptable manufacturers that comply with this specification section are listed below:

a.

FARBE

Via Udine 63

33030 Maiano (UD)

Tel.: 0432-959406

Fax.: 0432-959219 b.

RIVVEK

Via Boscalto 10/12

31023 Resana (TV)

Tel.: 0422-480045

Fax.: 0422-480022

c. RAN KOVER RK S.R.L.

Via Camatte, 1

37040 Zimella (VR)

Tel.: 0442-85700

Fax.: 0442-410974

2.2

METAL SUPPORT SYSTEM

Metal support system for exterior suspended ceiling plaster on metal lath as specified in Section 09100, "Metal Support Systems”.

2.3

ACCESSORIES

2.3.1 Corner beads, stops, control joints, and other accessories shall be stainless steel or galvanized steel, predrilled with flanges 2.5 centimeters wide, as minimum.

PART 3 - EXECUTION

3.1

GENERAL

Metal lath reinforcement shall be applied straight, without buckles. Metal lath reinforcement shall be applied over joints between dissimilar materials, such as masonry and concrete. Strips of metal lath reinforcement shall be not less than 75 mm and be nailed at intervals not exceeding 150 mm. Contractor shall utilize specialized manpower for the execution of plasterwork.

3.1.1 Exterior Suspended Ceilings

Provide exterior stucco and quartz-resin coating on ceiling suspension system as indicated. Components of the ceiling suspension system are specified in Section 09100, “Metal Support Systems”.

3.2

STUCCO MIXING

Cement and aggregates for each batch shall be accurately measured and mixed dry until evenly distributed and until the mass is uniform in color. No frozen, caked, or lump material shall be used. Batches shall be of such size that they can be entirely used within 1/2 hour. Except when hand-mixing such small batches is specifically approved, mechanical mixers of an approved type shall be used for the mixing of the stucco. Mechanical mixers, mixing boxes, and tools shall be cleaned after mixing each batch and kept free of stucco from previous mixes. Water content shall be maintained at a minimum. Mixing shall be continued until plasticity is obtained. Mortar that has begun to set shall not be used. Re-tempering will not be permitted. A water repellent shall be added to the finish coat. If in liquid or paste form, the repellent shall be always added to the finish coat. If in powder form, the water repellent shall be well mixed with the cementing materials. If in liquid or paste form, the repellent shall be added to, and mixed with the mixing water. The quantity of compound used shall provide 100 g of fatty acid for 50 kg of content in the finish coat.

3.3

STUCCO PROPORTIONS

Proportions of materials for stucco, by volume, shall be as follows:

3.3.1 Portland Cement Stucco

a.

Scratch Coat:

1 part Portland cement

3 parts fine aggregates

1/10 part hydrated lime b.

Finish Coat:

(1) Natural Grey: Natural grey Portland cement shall be of the same mix as specified for scratch coat.

3.4

APPLICATION OF STUCCO

3.4.1 Workmanship

Surfaces to receive stucco shall be clean, free from dirt, dust, oil, soot and other particles that might interfere with a satisfactory bond. Stucco coats shall be applied continuously in one general direction without allowing mortar to dry at edges. Masonry surfaces to receive stucco shall be evenly dampened (not soaked) with a fine fog spray of water before stucco is applied. If surfaces become dry in spots, the dry areas shall be dampened again to restore uniform suction. Where it is impossible to work the full dimension of a wall surface, jointing shall be made at a break, opening or other natural division of the surface. Edges to be joined shall be dampened slightly to produce a smooth confluence. Stucco, unless otherwise shown or specified, shall be two coat work not less than 20 mm thick. Stucco on soffit surfaces shall be pitched forward to form a drip.

3.4.2 Scratch Coat

The scratch coat shall be approximately 8 millimeters thick over the reinforcement that is placed at 6 millimeters from the backing, shall be applied under sufficient pressure to form good keys and to completely embed the reinforcement and shall be brought to a plumb, true, even surface, but left rough in texture. Before the scratch coat has set, it shall be well cross-scratched to provide a strong bond. The scratch coat shall be moist-cured 48 hours before the finished coat is applied. When measured with a 2 m long straight edge applied in all directions, the finished surface shall not vary from a true plane by more than 2.5 mm.

3.4.3 Finish Coat

The finish coat will be approximately 6 millimeters thick. Surfaces of the scratch coat shall be dampened several hours before the finish coat is to be applied as above indicated. Additional moistening at time of application shall be by fine fog spray of water. Moistening by brush will not be permitted. The finish coat shall have a float-texture finish. When measured with a 2 meters long straight edge applied in all directions, the finished surface shall not vary from a true plane by more than 2.5 millimeters. Finish shall be suitable for the selected painting type.

3.4.4 Curing

As soon as finished coat has taken its initial set, the stucco shall be protected against direct rays of the sun or rapid drying for at least six days. During this time, stucco shall be kept moist by frequent fine fog spraying of water. Care shall be taken to prevent staining of this stucco.

3.5

CONTROL JOINTS

Provide control joints in stucco surfaces as recommended by the manufacturer, but no less than every 16 square meters.

3.6 ACCEPTANCE AND REPAIRING

Work with cracks, blisters, pits, checks, or discoloration will not be accepted. Work shall be clean and sound and in accordance with the requirements of these specifications. After all other related work has been completed, pointing around trim and set work and repairing of damaged portions shall be performed to the satisfaction of the Contracting Officer’s Technical Representative. Repairs shall match existing work in texture and color.

3.7

CLEANING

On completion of the work, the scaffolding, the equipment, and the rubbish resulting from this work shall be removed from the site.

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Section 09212

Section 09212