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Historic Preservation - Technical Procedures

Spectitle:

Removing And Replacing Built-Up Roofing Using Cold-Applied Mastics

Procedure code:

0751501R

Source:

Federal Bldg & Uspo/Spokane, Wa - Gsa/Pbs

Division:

Thermal And Moisture Protection

Section:

Cold Applied Bituminous Roofing

Last Modified:

02/24/2012

Details:

Removing And Replacing Built-Up Roofing Using Cold-Applied Mastics



REMOVING & REPLACING BUILT-UP ROOFING USING COLD-APPLIED MASTICS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure provides guidance on removing and
         installing a cold process built-up roof.  This includes
         work for the following:

         1.   Removing an existing built-up roof, insulation,
              cants and flashings to the deck or substrate.

         2.   Priming concrete decks where applicable.

         3.   Loose laying vapor barrier on new metal decks where
              applicable.

         4.   Installing cricketing and field-tapered insulation
              as required, except where no rigid insulation is to
              be installed.

         5.   As applicable, mechanically fastening new
              insulation at metal decks, or priming deck and hot
              mopping at concrete deck areas.

         6.   Installing specified cold process roof system over
              substrate as required.

         7.   Installing pitch pockets as required.

         8.   Installing sheet lead at all drains (4 lb. lead
              typical).

         9.   Installing new lead vent stack flashings (materials
              furnished by others but installed herein).

         10.  Installing base flashings at all walls and
              equipment bases.

         11.  Installing traffic topping at areas where required.

         12.  Installing a surface mounted reglet flashing as
              required.

    B.   See 01100-07-S for general project guidelines to be
         reviewed along with this procedure.  These guidelines
         cover the following sections:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         4.   Quality Assurance

         5.   Delivery, Storage and Handling

         6.   Project/Site Conditions

         7.   Sequencing and Scheduling

         8.   General Protection (Surface and Surrounding)

         These guidelines should be reviewed prior to performing
         this procedure and should be followed, when applicable,
         along with recommendations from the Regional Historic
         Preservation Officer (RHPO).

1.02 REFERENCES

    A.   Cold-process membrane assembly shall be evaluated under
         the following applicable standards of the American
         Society for Testing and Materials (ASTM), 100 Barr Drive,
         West Conshohocken, PA 19428, (610) 832-9585 or FAX (610)
         832-9555.

         1.   ASTM D2523 load-strain properties of roofing
              membranes.

1.03 SYSTEM DESCRIPTION

    A.   Roof surfaces shall be sound, clean and dry, reasonably
         smooth and free from loose and foreign material and from
         depressions that would interfere with proper drainage.

1.04 SUBMITTALS

    A.   Product Data:  Prior to the application of any roofing
         materials, the roofing contractor shall submit to the
         Government the materials manufacturer's literature and
         descriptive information applying to the materials
         proposed for this project.  A letter shall be furnished
         from the material manufacturer indicating that all
         materials used on this project conform to their
         respective ASTM specification.  A conformation letter
         from a supplier will NOT be acceptable.  Under no
         circumstances shall the contractor start work prior to
         material approval.

1.05 QUALITY ASSURANCE

    A.   Qualifications:

         1.   The roofing contractor shall be certified bondable
              or guaranteeable by the roofing manufacturer.  The
              applicators shall have at least three years
              experience in applying the specified system.

         2.   Applicator shall be qualified under the
              manufacturer's guaranteed roof systems program.

         3.   Manufacturer Representative's Responsibilities
              shall be:

              a.   Rendering any inspection services the RHPO or
                   designated representative may request.

              b.   Calling to the attention of the contractor
                   those matters observed which he considers to
                   be in violation of the contract requirements.

              c.   Reporting to the RHPO or designated
                   representative in writing any failure or
                   refusal of the contractor to correct
                   unacceptable practices called to his
                   attention.

              d.   Confirming, after completion of the work and
                   based on his observations and test, that he
                   has observed no application and procedures in
                   conflict with the specifications, other than
                   those that may have been previously reported.
                   Final payment will not be released until this
                   confirmation has been received by the RHPO.

              e.   The presence and activities of the material
                   manufacturer's field representative shall in
                   no way relieve the contractor of his
                   contractual responsibilities.  In the event of
                   a dispute, the RHPO or designated
                   representative shall have final authority.

         4.   Bidders are required to visit the site to ascertain
              the local conditions readily determined by field
              inspection and inquire such as location,
              contractor's access area, general character of the
              site, and compare the plans and specifications with
              the field conditions.  Failure to visit the site
              will in no way relieve the contractor from
              furnishing any materials or performing any work
              required to complete the project in accordance with
              the specifications without any additional cost to
              the Federal Government.

    B.   Regulatory Requirements:  Comply with fire, safety and
         environmental protection regulations.

    C.   Pre-installation Conference:  A preconstruction
         conference will be held at which time the contractor will
         be given notice to proceed.  At this time the contractor
         shall submit all literature and samples required
         throughout the specifications for the installation of the
         vapor retarder, roof insulation, and roofing system.  The
         contractor and the job site superintendent shall attend
         the meeting.

1.06 DELIVERY, STORAGE AND HANDLING

    A.   Packing and Shipping:  

         1.   Deliver material in manufacturer's original,
              unopened containers with manufacturer's labels
              intact and legible.

         2.   Deliver enough material to allow continuous work.

    B.   Acceptance at Site:  Immediately remove and dispose of
         wet materials.

    C.   Storage and Protection:

         1.   Store rolls of felt, cartons of asphalt and cans
              and drums of cements, primers and coatings on end.

         2.   Store materials on clean, raised platforms.

         3.   Store and handle materials to protect them from:

              a.   Moisture, whether due to rain, snow or
                   condensation.

              b.   Damage by construction traffic.

              c.   Direct sunlight.

              d.   Mud, dust, sand, oil, grease and dirt.

         4.   Select and operate material handling equipment and
              store materials to keep from damaging existing
              construction or applied roofing.

1.07 PROJECT/SITE CONDITIONS

    A.   Environmental requirements:

         1.   Apply all roofing in dry weather.

         2.   Do not apply roofing when ambient temperature is
              below 40 degrees F. or when wind speed is over 30
              mph.

    B.   Protection:

         1.   Avoid heavy traffic on the work during all phases
              of installation.

         2.   Replace or restore to original condition any
              materials or work damaged during construction.

         3.   Protect paving and building walls adjacent to
              hoists, kettles and dumpsters.

         4.   Lap protective material at least 6".

         5.   Vent plastic sheets, if used, to keep moisture from
              condensing and collecting on covered surfaces.

         6.   Secure protective coverings against wind.

         7.   Leave protective covering in place until roofing
              work is complete.

         8.   Protect existing rooftop equipment against dust and
              debris entry.  Coordinate shutdown with RHPO.

1.08 WARRANTY

    A.   Work as specified under this specification shall be
         covered under the manufacturer's five (5) year guarantee
         program.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Tremco
         3735 Green Road
         Beachwood, OH  44122
         800/321-7906

2.02 MATERIALS

    A.   General:  Roofing components including, but not limited
         to, cold process adhesives, elastomeric flashings,
         reinforcement fabrics, felts, and mats, mastics, and
         sealants shall originate from single-source manufacturer
         consistent with the manufacturer's warranty requirements.
         Roofing ply sheets, rigid insulation, cover board, and
         roofing asphalt (for required hot mopping) meeting
         criteria specified herein may originate from any source.

    B.   Asbestos:  Products containing asbestos are prohibited on
         the project.  All roofing materials shall be completely
         asbestos-free.

    C.   Cold process roof system materials that may be
         incorporated in the work include, but are not limited to
         the following:

         1.   Tremco Burmastic Adhesive, or approved equal.

         2.   Tremco Tremlastic, or approved equal.

         3.   Tremco Double Duty Aluminum, or approved equal.

         4.   Tremco ELS Mastic, or approved equal.

         5.   Tremco Polyroof Elastomer, or approved equal.

         6.   Tremco 6" Burmesh, or approved equal.

         7.   Reglet Joint Sealant, as approved by system
              manufacturer.

         8.   Tremco TremPrime Q.D. Roof Primer, or approved
              equal.

         9.   Tremco Tremply Hypalon Base Flashing, or approved
              equal.

         10.  Tremco Sheeting Bond, or approved equal.

         11.  Traffic Topping:  Rubberized material approved by
              system manufacturer for heavy foot traffic.

         12.  Non-Shrink Grout, as approved by system
              manufacturer.

         13.  Reglet Primer, as approved by system manufacturer.

         14.  Reglet Cleaner, as approved by system manufacturer.

         15.  Sealant Tape, as approved by system manufacturer.

    D.   Ply Felts

    E.   Fasteners:

         1.   Buildex Roofgrip with 3" plate

         2.   Dekfast with 3" plate

         3.   Fabco with 3" plate

    F.   Vapor Retarder for New Metal Decking:  Laminated foil
         scrim, poly sheet with a maximum flame spread rating of
         5 (both surfaces) by U.L. classification.  Perm rating
         shall be .02 or less.  Provide accessory tape with same
         flame spread for joints.

    G.   Thermal Insulation:  Polyisocyanurate Foam Board
         Insulation:  Rigid boards of minimum 2.0 lb./cu. ft.
         density polyisocyanurate based foam core, permanently
         bonded to roofing felt facer sheets.  Provide in 3"
         thickness, with minimum aged K-value of 0.17.

    H.   Cover Board:  1/2" thick six-side asphalt coated fiber
         board.

    I.   Cants:  Fiber type, 3" minimum vertical rise.

    J.   Cricketing Material:  Perlite Board Roof Insulation:
         Rigid, noncombustible, perlite/fiber boards of
         thicknesses indicated, with k-value of 0.36 at 75 degrees
         F. (24 degrees C.), integrally skinned surfaces,
         complying with ASTM C 728.  Provide in manufacturer's
         standard sizes.  Note:  at contractor option, factory
         tapered perlite board may be furnished.

    K.   Coating at Existing Sheet Metal Roofs:

         1.   Tremco Tremlastic, or approved equal.

         2.   Primer:  as approved by manufacturer for coating
              and substrate.


PART 3---EXECUTION

3.01 PREPARATION

    A.   Protection:  A skilled, experienced foreman will be on
         the job at all times during the installation of the
         roofing.

         1.   The roofing contractor shall remove the existing
              roofing through the use of enclosed trash chutes or
              large bucket type containers.  No debris or trash
              shall be thrown from the roof edge.  Any damage
              resulting to exterior walls as result of the
              roofing operation shall be fully repaired to the
              satisfaction of the Government Representative.

         2.   The contractor shall NOT remove more roofing than
              can be adequately covered and waterproofed on the
              same day.  It is the contractors responsibility to
              keep the roof in a waterproof condition at all
              times throughout the life of this contract.

         3.   The contractor shall NOT pile or store debris on
              the roof surface.  All removed roofing shall be
              discarded on a daily basis.

         4.   Every precaution shall be taken to keep moisture
              out of the roofing during its application.  Felts,
              insulation and gravel shall be completely dry when
              laid.  No part of the roofing materials shall be
              applied or laid during damp or rainy weather, or
              while moisture of any kind is present in visible
              amounts on the surface to be covered.  Roof
              insulation or roofing felts that become wet from
              any cause during the progress of the work shall be
              removed from the job site in its entirety.

    B.   Surface Preparation:  

         1.   Apply temporary waterstops consisting of two plies
              of felts and moppings of asphalt at the end of each
              days work over the exposed edges of insulation and
              felts.  

         2.   Remove these temporary measures prior to the
              resumption of any additional work.

         3.   The contractor shall notify the Contracting Officer
              seven working days before any demolition on roofing
              work is started.  Roofing shall not be placed until
              such work has been inspected and permission given
              by the Government Representative.  The Government
              Representative shall inspect all roofing as it is
              applied.

3.02 ERECTION, INSTALLATION, APPLICATION

    NOTE:  ROOFING TO BE LAID IN STRICT ACCORDANCE WITH
    MANUFACTURER'S CURRENT PUBLISHED SPECIFICATIONS FOR ROOF
    DECKING MATERIALS INDICATED, AND ROOF DECK MUST BE DRY, SMOOTH
    AND CLEAN.

    A.   Phased application of the roofing materials (layer by
         layer, over several days) SHALL NOT BE DONE.  Work only
         on an area which can be completely roofed (up to
         protective coating) in a single working day.  At edges of
         new work, each successive layer shall leave some of the
         previous layer exposed for covering the next day.  Before
         the next day's work is begun, all dust, debris, bird
         droppings and moisture which has accumulated during the
         night shall be completely removed from the exposed edges
         before new material is added.

    B.   Tear Off and Removal:

         1.   Progressively remove the existing built-up roof
              membrane and insulation down to the deck by the use
              of hand tools or other means approved by
              authorities having jurisdiction for removal of
              existing materials containing asbestos fibers.
              Verify and comply with requirements imposed by
              regulatory agencies.  Transfer all debris off site
              to an appropriate landfill.  Pay all landfill
              charges.

         2.   Similarly remove base flashings from all perimeter
              vertical surfaces.  Leave all such surfaces
              sufficiently smooth to receive new base flashings,
              fully and adequately bonded.  DO NOT use
              sandblasting or other abrasive means to remove
              remaining residue.

         3.   Where indicated to remain unreplaced, remove and
              clean all drainage fittings, clamp rings, sumps and
              etc., on drains and store for later reinstallation.
              Plug drains to prevent debris entry.  Discard old
              lead.

         4.   Where necessary for proper installation of base
              flashings and equipment curbs, slit the corners of
              the sheet metal covers and vents and bend up sides
              which counterflash roof base flashings sufficiently
              to allow for the roofing work.

    C.   Decking:  After all the built-up roofing, insulation,
         etc. has been removed, the deck shall be thoroughly
         inspected for traces of deterioration.  If deck damage is
         present, repair or replace with the RHPO's approval
         before proceeding.  (Cost of deck repair will be paid on
         a change order basis as a concealed condition).

    D.   Vapor Retarder (at new metal decks only):  Install loose
         laid on deck just ahead of insulation.  Lap all joints 2"
         minimum and tape joints with flame spread rated accessory
         foil scrim tape.  Extend to top of cants.  Cover retarder
         with insulation board or cricketing layer(s) and
         mechanically fasten board as specified elsewhere.
         Install mechanical fasteners in insulation board or
         cricketing layer(s) having minimum 1-1/2" thickness.

    E.   Wood Nailers:

         1.   Install treated wood nailers at all perimeter metal
              edge flashings, metal flanges of roof top
              equipment, pitch pockets, vent stack leads and
              equipment support legs.

         2.   Nailer should be equal in thickness to the
              insulation.

    F.   Insulation:

         1.   Installation at Metal Decks:

              a.   Mechanically fasten the approved insulation to
                   the deck utilizing one of the approved fasteners.

              b.   Fasteners shall be installed at a rate of one
                   per every two (2) square feet of board.

         2.   Installation at Concrete Decks:

              a.   Prime concrete deck with one gallon primer per
                   100 sq. ft.

              b.   Install the approved insulation to the deck in
                   a uniform application of Type III hot asphalt
                   at a rate of 30 lbs. per 100 sq. ft.

              c.   "Walking in" the insulation boards is required
                   to assure good contact and uniform adhesion.

         3.   Cover Board:  Install over insulation as top layer.
              Use mechanical fasteners at metal deck.  Hot mop
              with Type III hot asphalt, 30 lbs. per 100 sq. ft.,
              at concrete decks.

         4.   Insulation General:

              a.   The insulation should be tightly butted
                   together with the joints staggered.  Offset
                   joints from any substrate plywood joints.

              b.   Installed insulation shall not be left exposed
                   to the weather.  It shall be covered and
                   waterproofed at once.  All exposed edges left
                   at the end of the day's work shall be
                   temporarily sealed.  Remove the cut-offs as
                   work progresses.

         5.   Crickets and Tapered Insulation:

              a.   At the areas indicated, install new crickets
                   to facilitate positive drainage.

              b.   Crickets shall be constructed of layers of
                   perlite set in Type III hot asphalt.

              c.   Prior to installing the approved insulation,
                   prime the cricket with manufacturer's
                   recommended primer at a rate of one gallon per
                   100 sq. ft., then set insulation board in Type
                   III hot asphalt at a rate of 40 lbs. per 100
                   sq. ft.

    G.   Cold Process Built-Up Roof Insulation:

         1.   All felts shall be rolled onto the roof surface,
              cut in 18' lengths and allowed to relax in the hot
              sun a minimum of 30 minutes.  (Felts shall be
              allowed to relax for longer periods of time on
              cooler days).

         2.   Starting at the point of the roof, apply over the
              insulation a uniform coating of cold process
              adhesive at a rate of 3 gallons per 100 sq. ft.

         3.   Embed into the cold process adhesive a 12", 24" and
              36" wide strip of roofing felt.  Overlap the 12"
              wide felt completely with the 24" and overlap this
              with the 36" wide roofing felt.  Continue to
              install full widths of felt, overlapping the
              preceding felt by 25" in shingle fashion.

         4.   Over all end laps, fully embed into the cold
              process adhesive one full ply of roofing felt, to
              hold down end curls, running perpendicular to the
              felt pieces.

         5.   Felts will be extended their full length and lapped
              4" creating a continuous joint at the felt ends.

         6.   Each ply of felt including the starting felt shall
              be solidly coated the full width with at least
              three gallons per square and nowhere shall felt
              touch felt.  The felt shall be broomed to assure
              complete contact without wrinkles, fishmouths or
              blisters.

         7.   Extend all plies to the edge of the roof or to the
              top of cant strips and cut off evenly.

         8.   Temporary water stops shall be installed at the
              completion of the day's work and removed before
              starting installation of the membrane the following
              work day.  No unfinished roofing shall be left
              exposed overnight.

         9.   Prior to the application of the top coating, all
              fishmouths shall be cut and reinforced with roofing
              felt and cold process adhesive.  All ridges shall
              be cut and repaired with a 12", 24" and 36" ply of
              felt.

    H.   Base Flashings:

         1.   Extend all roofing plies over the cant strip and
              cut off evenly.

         2.   Apply sheeting bond 1/8" thick to the entire wall,
              cant strip, and onto the roof surface 6".

         3.   Install hypalon base flashing.

         4.   Sheeting shall be of sufficient width to cover the
              wall and extend onto the roof 4" beyond the lower
              edge of the cant except where reglet conditions are
              indicated.

         5.   Secure the hypalon sheeting to the outside edge of
              the wood nailers (when provided) on the parapet
              walls and the top of the equipment curbs 8" on
              center with Simplex 1" square head roofing nails.

         6.   Install metal copings, surface mounted reglets and
              counterflashings at the areas indicated to cover
              and secure all exposed fasteners.

         7.   Seal all exposed vertical edges of base flashing
              with a 1/8" x 1" galvanized closure bar.  Apply
              tape to wall; apply hypalon to tape; apply another
              layer of tape; apply closure bar to tape and fasten
              with fasteners at 6" on center.

         8.   Seal the lower edge of the hypalon sheet with a
              three course application of Polyroof and 6"
              Burmesh.

         9.   Splice all hypalon laps with sheeting bond and
              three course with Polyroof and Burmesh.

    I.   Metal Roof Flanges - perimeter metal edge, vent stacks,
         equipment pitch pockets, etc.

         1.   Under all metal roof flanges install wood nailers
              of equal thickness to the insulation.

         2.   Set all roof flanges on top of the roofing plies
              and in a bed of ELS mastic.

         3.   Apply Polyroof between all metal edge lap joints.

         4.   Nail the flange to the wood nailers with large head
              roofing nails 3" on center maximum.

         5.   Prime with approved primer.

         6.   Seal all flanges with a 5 course application of ELS
              mastic and 4" and 6" Burmesh.

    J.   Pitch Pockets:

         1.   Pitch pockets shall be 24 gauge galvanized steel 3"
              high with a 4" roof flange.

         2.   Pitch pockets shall allow for 2" of clearance
              between the penetration and the pitch pocket wall.

         3.   Fabricate the top edge of the opening with a 1/4"-
              1/2" hem bent to the outside.

         4.   Solder closed all four corners.

         5.   If the pitch pocket is used around an existing
              penetration and cannot be slipped over, then make
              it soldered or pop riveted.

         6.   The pitch pocket is installed over the roofing
              plies and set in a bed of ELS mastic nailed
              securely to the wood nailer which is under the
              flange, using large head roofing nails 3" on
              center.

         7.   Prime flanges with approved primer.

         8.   The roof flange is 5 coursed with ELS mastic and 4"
              and 6" Burmesh.

         9.   Fill the pitch pocket 2" with non-shrink grout.

         10.  Fill the pitch pocket with Polyroof so that the
              water will shed off the top.

         11.  Clean the pitch pocket interior with primer.

    K.   Drains (both new and re-used existing drains):

         1.   Remove and lift drainage fitting clamps, rings,
              etc. on drains.  Clean and store for later
              installation.

         2.   Taper insulation to create a 48" x 48" sump around
              drain.

         3.   Plug drains to prevent debris entry.

         4.   Apply two layers of 1" caulking tape to the drain
              bowl.

         5.   Install all roofing plies into the drain bowl.

         6.   Discard existing lead sheets and replace with
              minimum 30" square, 4 lb. lead.

         7.   Embed new lead in Polyroof and install on top of
              plies of built-up roofing system.  Extend lead 1"
              beyond the clamping ring and bend down into the
              bowl.

         8.   Flash edges of lead with a 5 course of Polyroof and
              Burmesh.

    L.   Lead Vent Pipe Flashings:  Install over the completed
         plies bedded in with ELS mastic, nailed maximum 3" on
         center into wood nailers which are installed under the
         plies, the 5 coursed with ELS mastic and 4" and 6"
         Burmesh (Burmesh is covered with 1/8" of ELS mastic to
         cover green mesh).

    M.   Miscellaneous Flashing and Roof Top Equipment:

         1.   Reinstall pipe and conduit flashings, reset
              ventilators on curbs and secure to match existing.

         2.   Where corner metal flashings were or are opened and
              side of flashings bent up to allow space for
              working, bend flashings back down to the original
              position and fasten a prefabricated 24 gauge
              corner.

              a.   Insert prefabricated sheet metal corners,
                   lapped under a minimum 2" at sides and top,
                   under all corners.  Secure the position using
                   a minimum of 4 pop rivets or self-tapping
                   sheet metal screws.

         3.   Any existing flashings, drainage fittings and wood
              blocks, which are damaged shall be replaced to
              match the existing as part of this work.

    N.   Cold Process System Protective Coating:

         1.   Apply protective coating after all phases of the
              cold process roof have been completed leaving a
              watertight system with a solid smooth built-up roof
              base.

         2.   Allow the cold process system to cure a minimum of
              30 days.

         3.   Prior to the application of protective coating,
              wash down the entire surface and allow to dry.

         4.   Apply coating to the roof surface and base
              flashings at the rate of 4-1/2 gallons per 100 sq.
              ft.  Care must be taken to assure uniform coverage
              and appearance.  Excess piles and accumulation will
              not be accepted and must be brushed out.

    O.   Aluminum Reflective Coating:

         1.   Allow the protective coating to cure a minimum of
              30 days.

         2.   Wash the roof surface and allow it to completely
              dry.

         3.   Apply aluminum reflective coating to the roof
              surface and base flashings at a rate of 150 sq. ft.
              per gallon.  Aluminum may be sprayed, rolled or
              brushed.

    P.   Traffic Toppings:

         1.   Install traffic topping at the areas indicated.

         2.   TremTreds (or approved other) are to be installed
              in a full liberal application of roof mastic.

                             END OF SECTION