Spec 07510 - roofing.doc

01-05M

SECTION 07510

BITUMINOUS BUILT-UP ROOFING

SPEC WRITER NOTES:

1.

Delete information not specifically related to this project.

2.

Delete paragraphs not applicable and renumber the paragraphs.

3.

Delete between //____// if not applicable to project.

PART 1 GENERAL

1.1 DESCRIPTION

This section includes bituminous built-up roofing, aggregate surfacing, with base flashing for new construction // repairs and alterations to existing construction. //

1.2 RELATED WORK

SPEC WRITER NOTE: Edit Related Work to indicate other Sections relating directly to this section or referenced in this section.

A.

Gypsum Concrete Systems: Section 03511, GYPSUM PLANK DECKING // Section 03511, GYPSUM CONCRETE DECKS. //

B.

Insulating Concrete Systems: Section 03520, INSULATING CONCRETE ROOF DECKS // Section 03522, INSULATING CONCRETE INTERSTITIAL DECK. //

C.

Wood cants, blocking, and wood edge strips: Section 06100, ROUGH CARPENTRY.

D.

Wood sheathing: Section 06100, ROUGH CARPENTRY.

E.

Insulation: Section 07220, ROOF AND DECK INSULATION.

F.

Vapor barrier: Section 07220, ROOF AND DECK INSULATION.

G.

Base sheet for insulated roof assemblies: Section 07220, ROOF AND DECK INSULATION.

H.

Metal base flashing, pipe flashing, counter flashing, //gravel stop, fascia, coping, gutter and downspout, splash pan, reglet, insulated expansion joint cover, scupper //: Section 07600, FLASHING AND SHEET METAL.

I.

Extruded aluminum gravel stop, coping, fascia, and expansion joint cover: Section 07700, ROOF SPECIALTIES AND ACCESSORIES.

J.

Concrete pavers for roof walkways and equipment surrounds: Section 07570, PAVERS AND AGGREGATE ROOF BALLAST.

1.3 aPPLICABLE PUBLICATIONS

A.

Applicable publications listed below form a part of this Specification as referenced. Publications are referenced in the text by the number designation only.

B.

American Society for Testing and Materials (ASTM):

D41-94(R2000) Asphalt Primer Used in Roofing, Dampproofing and Waterproofing

D43-00 Coal Tar Primer Used in Roofing, Dampproofing and Waterproofing

D227-03 Coal-Tar Saturated Organic Felt Used in Roofing and Waterproofing

D312-00 Asphalt Used in Roofing

D450-96(R2000) Coal-Tar Pitch Used in Roofing, Dampproofing and Waterproofing

D1863-03 Mineral Aggregate Used on Built-Up Roofs

D2178-04 Asphalt Glass Felt Used in Roofing and Waterproofing

D3909-97b(R2004) Asphalt Roll Roofing (Glass Felt) Surfaced with Mineral Granules

D4586-00 Asphalt Roof Cement, Asbestos Free

D4601-98 Asphalt Coated Fiberglass Base Sheet Used In Roofing

D4897-01 Asphalt Coated Glass Fiber Venting Base Sheet Used in Roofing

D6163-00 Specification for Styrene Butadiene Styrene (SBS) Modified Bituminous Sheet Materials Using Glass Fiber Reinforcements

E108-04 Fire Tests of Roof Coverings

E119-00 Test Method for Fire Tests of Building Construction and Materials

F1667-03 Driven Fasteners: Nails, Spikes, Staples

C.

FM Global (FMG):

P7825C-03 Approval Guide Building Materials

4450:

Approved Standard for Class 1 Insulated Steel Deck Roofs

4470:

Approved Standard for Class 1 Roof Coverings

D.

National Roofing Contractors Association (NRCA):

"Quality Control Guidelines for the Application of Built-up Roofing."

"The NRCA Roofing and Waterproofing Manual"

1.4 warranty

Roofing system is subject to terms of "Warranty of Construction" Article in Section 01001, GENERAL CONDITIONS, except that warranty period is extended to five years.

1.5 QUALITY CONTROL

A.

Applicator Qualifications: Installer experienced in installation of systems similar in complexity to that required for this Project, including specific requirements indicated:

1.

Work shall be performed by installer approved in writing by roofing material manufacturer.

2.

Work shall comply with printed instructions of the roofing materials manufacturer.

B.

Product/Material Qualifications:

1.

Provide manufacturer’s label on each container or certification with each load of bulk bitumen, indicating Flash Point (FP), Finished Blowing Temperature (FBT), Softening Point (SP), Equiviscous Temperature (EVT).

2.

Provide manufacturer’s certification that field applied bituminous coatings and mastics, and field applied roof coatings comply with limits for Volatile Organic Compounds (VOC) per the National Volatile Organic Compound Emission Standards for Architectural Coatings pursuant to Section 183(e) of the Clean Air Act with limits as follows:

a.

Bituminous Coatings and Mastics: 500 g/l (4.2#/gal.).

b.

Roof Coatings: 250 g/l (2.1#/gal.).

3.

Obtain products from single manufacturer or from sources recommended by manufacturer for use with roofing system.

C.

Comply with the recommendations of the NRCA “Roofing and Waterproofing Manual” applicable to built-up roofing for storage, handling and installation.

D.

FMG Listing: Provide roofing membrane, base flashing, and component materials that comply with requirements in FMG 4450 and FMG 4470 as part of a roofing system and that are listed in FMG "Approval Guide" for Class 1 or noncombustible construction, as applicable. Identify materials with FMG markings.

SPEC WRITER NOTE:

1.

Select one option in first subparagraph below based on windstorm classification of Project. FMG Loss Prevention Data Sheet 1-28 multiplies the actual field-of-roof uplift pressure by a factor of 2 to obtain the factored pressure, the number that establishes the minimum FMG approval rating.

2.

Verify availability of roofing systems that meet these classifications. Other options for classifications increase in increments of 15, e.g., Class 1A-135, 1A-150, 1A-165, and higher.

3.

"Class 1A" signifies meeting ASTM E108, Class A fire performance for FMG-approved Class 1 roof coverings.

4.

For areas having three or more hailstorms annually, FMG recommends roofing systems rated SH (severe hail) instead of MH (moderate hail).

1.

Fire/Windstorm Classification: Class 1A-60 // 75 // 90 // 105 120 //.

2.

Hail Resistance: MH // SH //.

1.6 SUBMITTALS

A.

Submit in accordance with Section 01340, SAMPLES AND SHOP DRAWINGS.

B.

Product Data:

1.

Asphalt materials, each type.

2.

// Coal-tar materials, each type. //

3.

Roofing cement, each type.

4.

// Roof walkway. //

5.

Fastening requirements.

C.

Certificates:

1.

Indicate materials and method of application of roofing system meet requirements of FMG.

2.

Statements of qualification for manufacturers and installers.

3.

Inspection Report: Copy of roofing system manufacturer's inspection report certifying completed roofing complies with manufacturer’s warranty requirements.

D.

Warranty: As specified in Part 1 of this Section:

1.

Warranty sample form with specific language to address Contract provisions.

E.

Contract Close-out Submittals:

1.

Maintenance Manuals.

2.

Warranty signed by installer and manufacturer.

1.7 DELIVERY, STORAGE AND MARKING

A.

Deliver roofing materials to the site in original sealed packages or containers marked with the name and brand or trademark of the manufacturer or seller.

B.

Keep roofing materials dry and store in a dry, weather-tight facility or under canvas covers. Do not use polyethylene or plastic covers to protect materials. Store above ground or deck level on wood pallets. Cover ground under pallet stored materials with plastic.

1.

Store rolled materials (felts, base sheets, and paper) on end. Do not store hems on top of rolled materials.

2.

Aggregates shall be maintained surface dry as defined by ASTM D1863.

C.

Protect from damage due to handling, weather and construction operations before, during and after installation.

1.8 Environmental Requirements

A.

Weather Limitations: Proceed with installation only when existing and forecasted weather conditions permit roofing system to be installed according to manufacturer's written instructions and warranty requirements.

B.

Environmental Controls: Refer to Section 01568, Environmental Protection.

C.

Protection of interior spaces: Refer to Section 01010, General Requirements.

PART 2 – PRODUCTS

2.1 Roofing System

SPEC WRITER NOTE: Always retain paragraph below. The term bitumen, as defined in ASTM D1079, includes both asphalt and coal-tar pitch in roofing applications.

A.

Install built-up roofing membrane system according to roofing system manufacturer's written instructions and applicable recommendations of NRCA "Quality Control Guidelines for the Application of Built-up Roofing."

SPEC WRITER NOTE:

1.

Delete substrates and listings of components and quantities which do not apply.

2.

Include the requirement for base sheet or venting base sheet when roofing is uninsulated. Do not include this requirement when the roof is insulated per 07220 or the substrate is plywood.

3.

No coal tar bitumen system is provided. Use asphalt bitumen system and substitute “coal-tar” for “asphalt” and change materials to those listed for coal tar.

B.

Glass sheet, asphalt bitumen, mineral surfaced.

1.

Substrate: Plywood // Wood. //

2.

Components: Quantity.

a.

// Base Sheet: 1 Ply dry // b.

Base Sheet: 1 Ply c.

Ply Sheet: 2 Plies d.

Mineral Surfaced Cap Sheet: 1 Ply e.

Asphalt On Base Sheet 10-17.5 kg/10 sq. meters (20-35 lbs/100 sq. ft.)

f.

Asphalt Between Each Ply 10-17.5 kg/10 sq. meters (20-35 lbs/100 sq. ft.)

SPEC WRITER NOTE: Include the requirements for one ply of ventilating base sheet and three plies of ply felt where substrate is cast-in-place insulating concrete or precast concrete or aged concrete suspected of having retained moisture. This requirement specified in 07220 when substrate is insulated.

1.

Substrate: Roof Insulation // Cast-In-Place Concrete // Precast Concrete. //

2.

Components: Quantity a.

// Ventilating Base Sheet: 1 Ply // b.

Ply Sheet: 3 // 2 // Plies c.

Mineral Surfaced Cap Sheet: 1 Ply d.

Asphalt Between Substrate // Ventilating Base Sheet, // and First Ply: 10-17.5 kg/10 sq. meters 20-35 lbs/100 sq. ft.

e.

Asphalt Between Each Ply 10-17.5 kg/10 sq. meters 20-35 lbs/100 sq. ft.

3.

Provide asphalt quantities within the indicated ranges, unless recommended otherwise in the roofing materials manufacturer's printed data.

2.2 MATERIALS

A.

Primer: ASTM D41.

B.

Base Sheet: ASTM D4601, Type II, nonperforated, asphalt-impregnated and coated, glass-fiber sheet, dusted with fine mineral surfacing on both sides.

C.

Venting Base Sheet: ASTM D4897, Type II, venting, nonperforated, heavyweight, asphalt-impregnated and -coated, glass-fiber base sheet with coarse granular surfacing or embossed venting channels on bottom surface.

D.

Asphalt: ASTM D312, Type III or IV for roof membrane. Use Type I for pour coat unless specified otherwise.

E.

Ply Sheet/Backer Sheet: ASTM D2178, Type VI, heavy-duty ply sheet.

F.

Cap Sheet: ASTM D3909, asphalt-impregnated and -coated, glass-fiber cap sheet, with white coarse mineral-granule top surfacing and fine mineral surfacing on bottom surface.

G.

Roof Cement: ASTM D4586, Type I // Type II //.

H.

Flashing Sheet: ASTM D6163, Type I or II, glass-fiber-reinforced, SBS-modified asphalt sheet; granular surfaced; suitable for application method specified.

SPEC WRITER NOTE: Coal-tar BUR systems are typical for flat or minimally sloped roofs or roofs designed for water cooling, water retaining, or restricted drainage where asphalt BUR systems should not be considered. Do not use coal tar on slopes over 1:10 (one inch per foot).

//2.3 COAL-TAR MATERIALS

A.

Primer: ASTM D43.

B.

Organic Felt: ASTM D227, except bitumen shall be low fuming, non-blooming type.

C.

Coal-Tar Bitumen: ASTM D450, Type III.

D.

Roof Cement: Roofing manufacturer’s standard, asbestos free. //

2.3 MISCELLANEOUS materials

A.

Aggregate:

1.

ASTM D1863, except the use of crushed stone is prohibited.

2.

Slag or gravel. Use slag on slopes over 1:10 (one inch per foot).

B.

Roof Walkway:

1.

Prefabricated asphalt plank consisting of a homogeneous core of asphalt, plasticizer and inert fillers, bonded by heat and pressure between two saturated and coated sheets of felt:

a.

Topside of plank surfaced with ceramic granules.

b.

Size: Minimum 13 mm (1/2-inch) thick, manufactures standard size, but not less than 300 mm (12 inches) in least dimension and 600 mm (24 inches) in length.

2.4 FASTENERS

A.

Nails and Staples: ASTM F1667.

B.

Nails for Securing built-up Flashing and Base Sheets to Wood Nailers and Deck:

1.

Zinc coated steel roofing nails with minimum head diameter of 10 mm (3/8-inch) through metal discs at least 25 mm (one inch) across.

2.

One-piece nails with an integral flat cap at least 24 mm (15/16-inch) across.

C.

Fasteners for Securing Dry Felt Edge Strips to Wood Nailer and Decks:

1.

Zinc coated steel roofing nails, 16-mm (5/8-inch) minimum head diameter.

2.

Staples, Flat top Crown, zinc coated may be used.

D.

Nails for Plywood:

1.

Use annular thread type at least 19 mm (3/4-inch) penetration of plywood.

2.

16 mm (5/8-inch) minimum head diameter.

3.

Nails with flat cap at least 24 mm (15/16-inch) across.

//E.

Nails for attaching built-up Flashing to Masonry:

1.

Hardened steel nails through metal discs at least 25 mm (one inch in diameter).

2.

One-piece nails with an integral flat cap at least 24 mm (15/16-inch) across. //

//F.

Nails for Securing Venting Base Sheet to Insulating Concrete:

1.

Self clinching type of galvanized steel having an integral flat cap at least 25 mm (one-inch) across.

2.

Holding power of nails not less than 27 Kg (60 pounds) when pulled from approximate 400 Kg/m³ (26 pound per cubic foot) dense concrete. //

//G.

Nails for Securing Base Sheet to Structural Wood Fiber Decks:

1.

Self clinching type having an integral flat cap not less than 25 mm (one inch) across.

2.

Holding power of nails not less than 18 Kg (40 pounds) per fastener. //

//H.

Nails for Securing Base Sheet to Poured Gypsum Roof Deck:

1.

Special shaped nail providing diverging or hooking point.

2.

Flat cap not less than 32 mm (1-1/4 inch) across.

3.

Withdrawal resistance of not less than 18 Kg (40 pounds) per fastener. //

PART 3 – EXECUTION

3.1 EXAMINATION

A.

Verification of Conditions: Examine substrates, areas and conditions under which Work is to be performed and identify conditions detrimental to proper or timely completion:

1.

Do not proceed until unsatisfactory conditions, including moisture, have been corrected.

2.

Do not install roofing materials over wet insulation.

3.

Do not install roofing materials unless roof openings, wood nailers, edge venting, insulation board, flashing, curbs, and roof joints are constructed.

4.

Do not install roof materials unless deck and/or insulation provides designed drainage to working drains.

B.

Uninsulated Concrete Decks, except Insulating Concrete:

1.

Test deck for moisture prior to application of roofing materials.

2.

Test by pouring one pint of hot bitumen at 204 degrees C (400 degrees F.) or EVT on deck at start of each day's Work and at start of each new roof area or plane. Do not proceed if test sample foams or can be easily (cleanly) stripped after cooling.

C.

Insulating Concrete:

1.

Allow deck to dry before installing materials.

D.

Do not apply roof system if roofed deck will be used as a work platform.

E.

Existing Intake Louvers:

1.

Use large fans during placement to direct airflow away from existing intake louvers.

2.

If required to install roof near intake louvers after work hours, it shall be done so without additional cost to the Government.

3.2 PREPARATION

A.

Sweep substrate to broom clean condition. Remove all dust, dirt and debris.

B.

Remove surface irregularities that may damage materials or cause installation defects.

SPEC WRITER NOTE: Include one of the two paragraphs below if roofing assembly is uninsulated. Deck preparation for insulated decks is covered in Section 07220.

//C.

Prime concrete deck or precast units.

1.

Keep primer back 100-mm (4 inches) from joints in precast units. //

//C.

Cover wood sheathing, gypsum, gypsum plank and cement wood fiber plank with a layer of asphalt building paper. // C.

Coordinate operations with roof insulation and sheet metal work to permit continuous roofing operations.

3.3 INSTALLATION

SPEC WRITER NOTE: List in order of installation, starting at substrate.

A.

Comply with roofing system manufacturer's written instructions and applicable recommendations of NRCA "Quality Control Guidelines for the Application of Built-up Roofing."

B.

Cooperate with inspection and test agencies required to perform services in connection with built-up roofing system installation.

C.

General:

1.

Provide uniform and positive adhesion between all installed materials, including adhesion to insulation or substrate, and between each ply of felt.

2.

Substrate Penetrations: Do not allow bitumen to penetrate joints or enter building. Where mopping is applied directly to a substrate, tape joints. When applying steep asphalt, hold mopping back 50mm (2 inches) from each side of joint.

D.

Asphalt // Coal-Tar // Products Schedule:

1.

Use asphalt only with asphalt-saturated or asphalt-impregnated felts.

2.

Use Type I asphalt for pour coats up to 1:10 (one inch per foot) slope.

SPEC WRITER NOTE: For hot regions of the U.S., particularly in the Southwest, roofing asphalt with a softening point of one level higher than necessary, e.g., Type IV rather than Type III, shall be used.

3.

Coats on slopes oven 1:10 (one inch per foot).

4.

Use asphalt roof cement with asphalt products.

//4.

Use coal tar and coal tar roof cement with coal-tar-saturated felts, except asphalt-saturated felt base flashing with asphalt roof cement may be used in conjunction with coal-tar roofing.//

E.

Bitumen Schedule:

1.

Per square, unless otherwise specified.

2.

Between substrate and plies of organic felt:

SPEC WRITER NOTE: Select bitumen type.

a.

Asphalt 7 to 11 Kg (15 to 25 pounds).

//a.

Coal tar, 9 to 14 Kg (20 to 30 pounds). //

3.

Between substrate and plies of glass fiber felts asphalt, 9 to 14 kg (20 to 30 pounds).

4.

Glaze Coats:

a.

Asphalt 7 to 11 Kg (15 to 25 pounds).

//a.

Coal tar, 9 to 14 Kg (20 to 30 pounds). //

5.

Pour coats:

a.

Asphalt 25 to 30 Kg (55 to 65 pounds).

//a.

Coal tar, 32 to 36 Kg (70 to 80 pounds). //

F.

Heating Bitumen:

1.

Heat the asphalt to the equiviscous temperature (EVT) plus or minus 4 C (25 degrees F) at the time of application.

a.

Do not heat asphalt greater than 38 C (100 degrees F) above the EVT.

b.

When the EVT is not furnished do not heat asphalt above 246 C (475 degrees F) for Type I and 275 C (525 degrees) F for Type II and IV, with an application not less than 218 C (425 degrees F) and 246 C (475 degrees F) respectively.

//1.

Do not heat coal-tar bitumen above 218 C (425 degrees F) with an application temperature ranging from 163 C (325 degrees F) to 204 C (400 degrees F). //

2.

Do not heat bitumen above the flash point temperature.

3.

Provide heating kettles with a thermometer kept in operating condition. Attend, during heating, to insure the bitumen is heated within the temperatures specified.

4.

Do not mix different types of bitumen in kettle.

G.

Terminations:

1.

Where cants occur at vertical surfaces, cut off plies of membrane 50mm (2 inches) above top of cant strip, (except at prefabricated curbs, scuttles and other roof accessories having integral cants) extend membrane over cant and up vertical surface to top of curb or blocking.

2.

Where wood blocking occurs at roof edge, under gravel stops or penetrations to receive base flashing, nail a continuous strip of 400 mm (16-inch) wide, loose applied organic felt envelope over the blocking before the first ply sheet is applied.

a.

Install strip on top of venting base sheet.

b.

After membrane is installed, turn the dry felt back over the roofing and secure in place with hot bitumen before gravel stops or metal flanges extending onto the membrane are installed.

3.

Where fascia/cant occurs at roof edges, extend membrane beyond outside face and cut off after base flashing is installed. // Do not cut off venting base sheet outside cant face, extend down over outer cant face to allow for venting. //

SPEC WRITER NOTE: Include Base sheet for all uninsulated wood decks. Base sheet for insulated wood decks specified in Section 07220.

H.

Base Sheet:

SPEC WRITER NOTE: Use with asphalt.

1.

One ply of base sheet dry to deck, except mop between laps. Lap and attach as specified to deck.

2.

For base sheet applied to wood deck of insulated assemblies: Refer to Section 07220.

SPEC WRITER NOTE: Use with coal-tar.

//1.

One ply of venting base sheet. Fasten base sheet down dry on deck. Lap and seal with roof cement. //

//2.

For base sheet applied to wood deck of insulated assemblies: Refer to Section 07220, ROOF AND DECK INSULATION. //

SPEC WRITER NOTE: Use venting base sheet over insulating concrete and poured gypsum decks to relieve vapor pressures. Base sheet for insulated concrete decks specified in Section 07220, ROOF AND DECK INSULATION.

I.

Venting Base Sheet:

1.

At vertical surfaces: Extend venting base sheet up vertical surface over cants to top of base flashing or curb.

2.

At roof edge under gravel stops install venting base sheet over blocking: Extend base sheet not less than 50 mm (2-inches) beyond outer edge and turn down to allow venting at the edge.

3.

At roof edge over fascia-cant: Extend base sheet over top of cant and turn down over outer face of cant to allow venting at the edge.

//1.

For base sheet applied to deck of insulated roof assemblies: Refer to Section 07220, ROOF AND DECK INSULATION. //

J.

Roof Ply Installation:

1.

Install, asphalt, glass fiber felt // coal tar bitumen, organic felt // construction. Base sheet is not considered a ply.

2.

Extend the first ply 100 mm (4-inches) beyond the insulation and the second ply 75 mm (3-inches) beyond the first. Lap ends 75 mm (3-inches) with joints broken 450 mm (18-inches) in each ply.

K.

Laps for felts and base sheet:

1.

Base sheet, lapped 50 mm (2-inches).

//2.

Two plies of felt with 450 mm (18-inches) and 900 mm (36-inch) starting widths, lapped 480 mm (19-inches). //

2.

Three plies of felt with 300 mm (12-inches) 600 mm (24-inches) and 900 mm (36-inch) starting widths, lapped 624 mm (24-1/2 inches).

//2.

Four plies of felt with 230, 460, 690 and 900 mm (9, 18, 27 and 36-inch) starting widths, lapped 700 mm (27-1/2 inches). //

3.

End joints of felt and base sheet, lapped 50 mm (2-inches). Stagger end joints in relation to joints in adjacent and proceeding plies.

SPEC WRITER NOTE: Use cold applied method for coal tar roofing

L.

Flashing:

1.

Prime vertical surfaces of masonry and concrete with asphalt primer except where vented base sheet is required to provide edge venting.

2.

Apply flashing on top of built-up roofing, up face of cant and vertical surfaces, at least 200 mm (8-inches) above the roof, full height beneath counter flashing or top of curb flashing:

a.

At fascia-cants, extend to top of cant and cut off.

//b.

Extend plies of roofing into reglet the full depth of the reglet.//

3.

Except at metal fascia cants, secure top edge of base flashing with nails on a line approximately one inch below top edge, spaced not more than 200 mm (8-inches) on center.

a.

Cover all nail heads with roof cement.

b.

Cover the top of the base flashing with counter flashing as specified in Section 07600, FLASHING AND SHEET METAL. At the cants secure the top edge of the flashing with fascia compression clamp as specified in Section 07600, FLASHING AND SHEET METAL.

4.

Install flashing using longest pieces practicable. Complete splices between flashing and main roof sheet before bonding to vertical surface. Seal splice not less than 76mm (3-inches) beyond fasteners that attach membrane to blocking. Apply bonding adhesive to both flashing and surface to which flashing is being adhered per manufacturer recommendations. Nail top of flashing 300mm (12-inches) on center under metal counter flashing or cap.

a.

Parapet Walls: Extend up parapet and turn over top edge. Apply with 100 percent adhesive.

5.

Install flashing over cants to make system watertight.

6.

Install flashing before final roofing coat and aggregate are installed.

M.

Stripping:

1.

Set flanges of metal flashing in roof cement before the final bituminous coat and roof aggregate are installed and nail to blocking per Section 07600, FLASHING AND SHEET METAL.

SPECS WRITER NOTE: Select for asphalt or coal-tar.

2.

Before the final bituminous coat and aggregate are installed, cover that portion of the horizontal flanges of metal base flashing, gravel stops and other flanges, extending onto the roofing with flashing sheet // consisting of two plies of organic felt with coal tar bitumen. //

N.

Aggregate Surfacing:

1.

After bituminous base flashing and stripping has been installed, uniformly coat the entire roof surface, except cants, with bitumen pour coat at the rate scheduled.

2.

Use type III asphalt on slopes over 1:10 (one inch per foot).

3.

While still hot, embed aggregate to cover the roofing sheet completely without bare spots, but not less than 20 Kg/m² (400 pounds/) of dry gravel or 15 Kg/m² (300 pounds/100 square feet) of dry slag per. Do not leave any exposed bitumen.

4.

Do not embed aggregate under roof walkways.

5.

In cold weather preheat aggregate prior to application.

6.

Do not place aggregate material in piles or rows on bare or glaze coated felt.

7.

If aggregate surfacing is delayed, promptly apply glaze coat of hot roofing asphalt at rate scheduled.

O.

Roof Walkways:

1.

Install roof walkways where shown.

2.

Prefabricated asphalt plank: sweep away loose roof aggregate from area to receive plank. Set planks in hot bitumen poured over the firmly embedded roof aggregate as specified for pour coat. Maintain minimum 75-mm (3-inches) to maximum of 150 mm (6-inches) space between planks.

//2.

Concrete Pavers: Refer to Section 07570, PAVERS AND AGGREGATE ROOF BALLAST. //

//3.4 REPAIR AND ALTERATIONS TO EXISTING ROOF

A.

Areas to be altered or repaired, remove loose aggregate and aggregate not firmly embedded where new penetrations occur or repairs are required:

1.

Remove aggregate 900 mm (3 feet) beyond areas to be cut.

a.

Clean, dry and store aggregate away from roof area until ready to reuse.

b.

Remove unsuitable and excess aggregate not used from Project.

B.

Cut and remove existing roof membrane for new work to be installed. Clean cut edges and install a temporary seal to cut surfaces. Use roof cement and one layer of 7 Kg (15 pound) felt strip cut to extend 150 mm (6 inches) on each side of cut surface. Bed strip in roof cement and cover with roof cement to completely embed the felt.

C.

Bend up cap flashing or temporarily remove at built-up base flashing to be repaired. Brush and scrape away deteriorated and loose bitumen, felts or surface material of built-up base flashing.

D.

Repairs to existing membrane and base flashing:

1.

Remove temporary patches prior to starting new work.

2.

Blisters and fish mouths:

a.

Cut blisters open and turn membrane back to fully adhered portion. Cut fish mouths so membrane can be turned back and subsequently laid flat.

b.

Heat membrane to facilitate bending and to dry surface of exposed blister areas.

c.

Mop turned back membrane in hot bitumen. Roll to insure full adhesion and embedment in substrate.

d.

Cover cut areas with two plies of felt. Extend first ply 100 mm (4-inches) beyond cut area edge. Extend second 100 mm (4 inches) beyond first ply. Mop down in hot bitumen as specified for new work. Resurface to match existing.

3.

Exposed Felts:

a.

Cut away exposed deteriorated edges of sheets.

b.

Glaze coat felt edges.

c.

Resurface to match existing.

4.

Built-up Base Flashing:

a.

Restore felts and cap sheet removed, lapping 100 mm (4-inches) over existing.

b.

Install new felts and cap sheet as specified for new work.

5.

Horizontal Metal Flanges:

a.

Remove loose, buckled or torn stripping.

b.

Remove loose fasteners and install new fasteners.

c.

Restrip flanges as specified for new work.

6.

Resurfacing:

a.

Over repaired membrane, embed aggregate as specified for new work.

b.

Cover all membrane areas. Do not leave any exposed membrane surface.

E.

Match existing roofing materials and construction. Use bitumen compatible with existing for roof repair and alteration.

F.

Perform alterations, maintenance and repairs to roof membrane immediately after membrane has been cut or damaged, with permanent new work as specified in this specification. Repair items damaged in surface preparation and aggregate removal.

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07510-1