Specification:Slate roofing

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=GENERAL=

SYSTEM DESCRIPTION
Salvage and reuse intact and serviceable existing slate materials whenever possible. New slate being incorporated into existing slate roofs shall match existing as closely as possible. Use slate from the same quarry or manufacturer as the original, if possible. Establish units of work, including removal of existing materials, preparation of existing surfaces and application of underlayment, nailers, and related temporary and/or permanent flashing. The progression of work shall be laid out and presented to the Contracting Officer to prevent other trades from working on or above completed roofing. Do no store materials on roof decks in such a manner as to overstress and/or damage the deck and supporting structure. Avoid placing of loads at midspans of framing so that superimposed loads are well distributed. Vertical surfaces which project through the roof surface at a right angle to the slope of the roof shall have a cricket (sometimes referred to as a saddle) built into the roof to divert water away from the back of the vertical member, as shown.

SUBMITTALS
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation are for [Contractor Quality Control approval.] [information only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government.] Submit the following in accordance with Section 01 33 00 SUBMITTAL PROCEDURES: SD-02 Shop Drawings Drawings[; G][; G, [_____]] SD-03 Product Data Qualifications SD-04 Samples Slate Accessories for Slate Roofs Sealants Underlayment Membrane Fasteners SD-07 Certificates Materials

QUALITY ASSURANCE
Provide qualified workers, trained and experienced in installing slate roofing systems of this configuration, and submit documentation of 5 consecutive years of work of this type. Show familiarity with and perform work in accordance with [SMACNA 1793] [and] [NRCA RoofMan.] As proof of Qualifications, submit documentation showing qualifications of personnel proposed to perform the roofing work, and a list of installations made identifying when, where, and for whom the installations were made. Submit drawings showing slate installation and appearance details, flashing details, and nailing patterns for the slates.

DELIVERY, STORAGE, AND HANDLING
Deliver materials in manufacturer's unopened bundles and containers with the manufacturer's brand and name marked clearly thereon. Store shingles in accordance with manufacturer's printed instructions and roll goods on-end in an upright position. Immediately before laying, store roofing felt for 24 hours in an area maintained at a temperature not lower than 10 degrees C 50 degrees F.

PROJECT/SITE CONDITIONS
Perform slate roofing operations when existing and forecasted weather conditions permit work in accordance with manufacturer's recommendations and warranty requirements. Apply elastomeric membrane underlayment only in fair weather when air and surface temperatures are above 5 degrees C 40 degrees F. Provide temporary protection materials maintained on the site at all times for temporary roofing, flashing, and other protection when delays and/or changed weather conditions do not permit completion of each unit of work prior to the end of each working day. Remove and discard materials which have been used for temporary roofing, flashing and other protection.

WARRANTY
Furnish a warranty against defects in material and workmanship of slate roof assembly, including related metal flashing for a period of 10 years from date of final acceptance of the work. Contractor shall inspect the completed project every 12 months for the first 3 years of the warranty period, at year 5 and a final inspection at year 10. Inspections shall be from a remote access device such as a bucket lift or cherry picker and shall not include any foot traffic on the slates. =PRODUCTS=

MATERIALS
Submit certificates of compliance attesting that the materials meet specification requirements.

Slate
Provide slate conforming to ASTM C406/C406M. Slate shall be Grade A, (ASTM S1), hard, dense rock, punched or drilled for two nails each. Cracked slate shall not be used. Exposed corners shall be full. Broken corners on covered ends which sacrifice nailing strength or the laying of a watertight roof will not be allowed. Submit three representative shingles to show color range.

Standard Thickness Roofing Slate
Slate shall be smooth texture] [rough texture [5 to 6 mm 3/16 to 1/4 inch thickness] [all [_____] thickness] _____] and [_____] intermingled thicknesses]. Slate shall be the following sizes: [[_____] by [_____ [graduated lengths] [and] [random widths].

Graduated Roof Slate
Slate shall be smooth texture] [rough texture and shall vary in thickness from [_____] at eave to [_____] at ridge; the percentage of each thickness to be respectively [_____]. The thicknesses shall be intermingled in the various courses, modulating from the heavier and thicker slates in the lower courses of the roof to the thinner slates at the ridge. Slate shall be in standard random widths graduated in length from [_____] at eave to [_____] at ridge, and shall be applied with standard 3 inch (75 mm) lap and exposures.

Slate Colors
Slate shall be [unfading] [semi-weathering] slate. Color shall be [in accordance with Section 09 06 90 COLOR SCHEDULE] [_____].

Underlayment Membrane
Furnish an underlayment membrane on all surfaces to be covered with slate. Membrane shall consist of [asphalt-saturated felt] [or] [high strength composite self-adhering membrane]. Submit a 300 by 300 mm 1 by 1 foot section.

Roofing Felt
Roofing felt shall be asphalt-saturated rag felt, Type II, No. 30 asphalt felt in accordance with ASTM D226/D226M.

Elastomeric Membrane Underlayment
Membrane shall be a cold applied composite self-adhering membrane of not less than 0.10 mm 0.004 inch high strength polyethylene film with slip resistant embossing, coated on one side with a thick layer of adhesive-consistency rubberized asphalt, interwound with a disposable silicone coated release sheet. The tensile strength and elongation values shall be not less than 1.7 MPa 250 psi when tested in accordance with ASTM D412 and pliability shall be unaffected when tested in accordance with ASTM D146.

Elastomeric Membrane Accessories
Two component urethane, mastic and primer shall be as approved by the membrane manufacturer. Flashing, expansion joint covers, temporary UV protection and corner fillets shall be as recommended by the membrane manufacturer.

Nails
Nails shall be large-headed slater's solid copper nails of Number 10 or 11 gauge metal. Nails shall be 3d for slates 450 mm 18 inch or less in length; 4d nails shall be used for slates 500 mm 20 inch or longer, and 6d nails shall be used for slates on hips and ridges. Thicker slates require longer and heavier gauge nails. The proper size shall be determined by adding 25 mm 1 inch to twice the thickness of the slate. Nails shall be of sufficient length to adequately penetrate the roof sheathing. Nails used to retain copper flashing and slate at rake edges, hips, ridges, and eaves prone to wind damage shall be of the ring shank design.

Flashing
Flashing shall be 0.57 kg 20 ounce, light cold-rolled temper (H00) copper conforming to ASTM B370. Flashing shall be in accordance with the requirements as specified in Section 07 57 13 FLASHING AND SHEET METAL.

Elastic Cement
Elastic cement shall be an approved brand of waterproof elastic slater's cement colored to match as nearly as possible the general color of the slate.

Acid Neutralizing Wash
Acid neutralizing wash shall be non-destructive wash formulated to neutralize the effects of acid deposits resulting from the past burning of fossil fuels (particularly coal). The wash shall not change the color, appearance, or life of the slate roof, copper flashing and accessories, underlayment, adhesives or the wall surfaces of the building.

Sealants
Sealants, where required, shall be in accordance with the slate manufacturer's recommendations. Submit 237 mL 8 ounces of each type.

Crickets or Saddles
Provide crickets of light rafter construction covered with sheathing, underlayment, and copper sheet metal specified in Section 07 57 13 FLASHING AND SHEET METAL. If the cricket area is large and exposed to view, it shall be slated the same as other roof areas.

Snow Guards
Provide nonferrous metal snow guards, as indicated. =EXECUTION=

PROTECTION OF ROOF SURFACES
Use equipment (such as padded ridge ladders) and techniques to prevent damage to roof as a result of foot or material traffic. Contractor is responsible for controlling breakage of new or existing slate beyond what is indicated. Personnel who are working on the roof shall wear proper shoes which will not further damage slates; shoe soles shall be made of a material which will aid in preventing falls.

Installation Plan
Submit a detailed installation plan for approval prior to beginning the work indicating the methods to be used to apply the slates to the roof and protect the installed slates from damage. The plan shall contain a narrative description and a drawing clearly depicting the layout for work access devices such as padded roof jacks for walkways, padded chicken walk placements between walkways, and other means of protecting newly installed slates and any existing slates to remain. Details shall be provided that clearly indicate how work access devices shall be installed/incorporated and the sequence of Work to include these devices. Under no circumstances shall any foot traffic be allowed on newly installed slates or existing slates to remain. The Plan shall indicate how the work access devices will keep foot traffic off the slates at all times.

Inspection
Contractor's quality control inspections and inspections by the Government shall take place as the Work progresses to coordinate with the installation and removal of the work access devices. Notify the Contracting Officer a minimum of 48 hours in advance of requested inspections and maintain work access devices in place to provide access to uninspected areas until final acceptance by the Government.

SLATE REMOVAL
Where work involves partial replacement or repair of roof, verify each slate for tightness and continued use. Perform testing with broad, flat-nosed, slater's pliers. Slates which have been identified for replacement or re-installation shall be marked with a non-destructive color mark removable by solvent, rather than water, and for approval within 30 days after Notice to Proceed. Slates fastened with non-copper fasteners shall be re-fastened with proper copper fasteners. Submit representative samples of each fastener with identifying tags.

PREPARATION OF SURFACES
Roof deck surfaces shall be smooth, clean, firm, dry, and free from loose boards, large cracks, and projecting ends that might damage the roofing. Foreign particles shall be cleaned from interlocking areas to ensure proper seating and to prevent water damming. Prior to installation of slate, vents and other projections through roofs shall be properly flashed and secured in position, and projecting nails shall be driven firmly home.

ROOFING FELT
Lay felt in horizontal layers with joints lapped toward eaves and at ends at least 50 mm 2 inches, and secured along laps and at ends as necessary to hold the felt in place and protect the structure until covered with the slate. Felt shall be preserved unbroken, tight and whole. Felt shall lap hips and ridges at least 300 mm 12 inches to form a double thickness and shall be lapped 50 mm 2 inches over the metal of valleys or built-in gutters.

Surface Preparation
Remove dust, dirt, loose nails or other protrusions. Priming is not required for wood or metal surfaces but is necessary on concrete or masonry surfaces.

Primer
Primer shall be applied at a coverage rate of 6-9 sq. meters/L 250-350 sq. ft./gal. Primer shall be applied by spray or paint roller. Pine wood decks shall be covered with minimum 6 mm 1/4 inch plywood prior to receiving membrane coverage.

Membrane Application
Apply membrane according to manufacturer's instructions and adhere it directly to roof deck. Cut the membrane into 3 to 4.5 meter 10 to 15 foot lengths and re-roll it. The release paper shall be peeled back 300 to 600 mm 1 to 2 feet; align the membrane on the lower edge of the roof when the first 300 to 600 mm 1 to 2 feet are placed. The release paper under the membrane shall be peeled from the membrane and the membrane pressed in place. Lower edges shall be rolled firmly with a wallpaper or hand roller. For ice dam protection, apply the membrane to reach a point above the highest expected level of ice dams; refer to drawings for extent. Ends and edges shall be overlapped a minimum of 150 mm 6 inches. Membrane shall not be folded onto an exposed face of the roof edge.

Valley and Ridge Application
Cut the membrane into 1.2 to 1.8 meter 4 to 6 foot lengths. The release paper sheet shall be peeled and centered over the valley or ridge, then draped and pressed in place, working from the center of the valley or ridge outward in each direction. For valleys, membrane shall be applied starting at the low point and working upwards. Overlap all sheets a minimum of 150 mm 6 inches.

Vertical Membrane Flashings
Vertical wall installations shall receive primer prior to the application of membrane. Primer shall be applied at a coverage rate of 6-9 sq. meters/L 250-350 sq. ft./gal. Membrane shall be turned up walls and dormers as indicated on the drawings. Vertical membrane terminations shall be mechanically fastened and shall receive a troweling of mastic as approved by the membrane manufacturer. Membrane may be folded onto the fascia, provided it will be covered by a gutter metal edge or other material.

Protection
Elastomeric membrane underlayment shall not be left permanently exposed to sunlight. Membrane shall be covered with exposed roofing materials as soon as possible. Membrane damaged due to exposure to sunlight shall be patched prior to the application of final roof covering.

METAL FLASHING
Metal flashing shall be as shown at intersections of vertical or projecting surfaces through the roof or against which the roof abuts, such as walls, parapets, dormers, and sides of chimneys. Flashing installation shall be in accordance with Section 07 57 13 FLASHING AND SHEET METAL.

Repair and Replacement
Existing reusable slates removed from the repair area shall be intermingled with new slates to provide a smooth visual transition between new and existing areas. Slating shall be applied as shown.

Slate Coursing
The slate shall project 50 mm 2 inches at the eaves and 25 mm 1 inch at gable ends, and shall be laid in horizontal courses with 75 mm 3 inch headlap (unless otherwise indicated), and each course shall break joints 1with the preceding one by at least 75 mm 3 inches. Slates at the eaves or cornice line shall be doubled and canted 6 mm 1/4 inch by a wooden cant strip, using same thickness slate for under-eaves at first exposed course. Under-eave slate shall be approximately 75 mm 3 inches longer than exposure of first course. There shall be no through joints from the roof surface to the underlayment.

Nailing
Fasten each slate with a minimum of two copper nails of sufficient length to penetrate the roof decking at least 19 mm 3/4 inch or through the decking thickness, whichever is less. Where the underside of roof decking is exposed to view, such as in overhanging eaves, the nails shall be long enough to penetrate the roof decking but not so long that they may be driven through the decking. The heads of slating nails shall just touch the slate and shall not be driven "home" or draw the slate, but left with the heads just clearing the slate so that the slate hangs on the nail. Nails in slates overlapping sheet metalwork shall not puncture the sheet metal. Exposed nails are permissible only in top courses where unavoidable, but covered with elastic cement. Hip slates and ridge slates shall be laid in elastic cement spread thickly over unexposed surface of under courses of slate, nailed securely in place and pointed with elastic cement.

Vertical Surfaces
Slate shall be fitted neatly around pipes, ventilators, chimneys and other vertical surfaces.

Hips
Hips shall be laid to form a [fantail] [saddle] [mitered] [Boston] hip as shown.

Ridges
Ridges shall be laid to form [comb] [saddle] [strip saddle] ridges. The nails of the combing slate shall pass through the joints of the slate below. The combing slate shall be laid with the same exposure as the next course down. Combing slates sloping away from the direction of the prevailing storms shall project 25 mm 1 inch above the combing slate on the opposite side of ridge.

Valleys
Valleys shall be laid to form [closed] [open] [round] valleys. Open-type valleys shall be formed with the main roof at cricket areas. The size of the cricket is largely determined by the roof condition. Unless noted otherwise, the slope of the cricket shall be the same as the slope of the roof.