Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
A. This procedure includes guidance on the removal of deteriorated built-up roofing, insulation, flashings, wood blocking and equipment pads, and replacing with new built-up roofing.
B. For additional guidance on inspecting and repairing flat roof systems, see 07500-01-S, 07500-02-S, 07510-01-S and 07511-02-R.
C. Safety: The employer is expected to work in accordance with OSHA standard.
D. See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precaution= s
- Quality Assurance
- Delivery, Storage and Handling=
- Project/Site Conditions
- Sequencing and Scheduling
- 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).
A. Roofing System: An assembly of related components consisting of the following:
- Preformed above deck roof insulation.
- Built-up bituminous roofing.
- Built-up base flashings and seals.
B. Non-Nailable Substrate: Any substrate for built-up roofing which is not intended to receive and hold mechanical fasteners such as cast-in-place concrete, precast concrete, block or board insulation, or lightweight insulating roof fill.
C. Bitumen: Coal-tar pitch or asphalt.
D. Built-Up Flashing: Any non-metallic bituminous flashing, including fabric and felt, applied with hot-mopped asphalt or cold process bituminous plastic flashing cements.
A. Product Data: Submit manufacturer's technical product data, installation instructions and recommendations for each type of roofing product required. Include data substantiating that materials comply with requirements.
- For asphalt bitumen, provide label on each container or certification with each load of bulk bitumen, indicating flash point (FP), finished blowing temperature (FBT), softening point (SP) and equiviscous temperature (EVT).
B. Shop Drawings - Tapered Insulation: Submit shop drawings for the tapered insulation system. Shop drawing shall include plan layouts having high point and low point dimensions. Details shall be provided which show clearances at base flashings, counter flashings, fascias, copings, curbs, etc.
C. Samples - Aggregate Surfacing: Submit 3-lb. Samples of aggregate surfacing material, flashings, insulation, fasteners, roofing cement and roofing membrane.
D. Design Data/Test Reports/Certificates:
- List of Materials: Furnish, with the certificates, a list of materials proposed for use in the roof system, including name of manufacturer, for approval.
- Certificates for Bituminous Materials: Furnish the following certification, in triplicate, endorsed by the built-up bituminous roofing materials manufacturer:
- That all materials in the roofing system are chemically and physically compatible.
- That the materials meet all the specified requirements, referenced specifications, standards and tests.
- Certificates for Insulation: Furnish the following certifications, in triplicate, from the manufacturer of the roof insulation:
- Certificates, signed by the Contractor and the insulation manufacturer, stating that insulation, including cant strips, conform to specified requirements, the thickness for the specified "U" factor, and that the materials are proper for use on this project and in conjunction with the specified roof system.
- Certificates for Materials Over Different Deck Types: Furnish evidence of approved laboratory labeling, listing or certificates attesting that materials and method of installation over various deck types meet specified test procedures and classification standards.
E. Manufacturer's Instructions/Field Reports: Submit daily softening point test reports on samples of asphalt used on project, taken at beginning of each day's work and at 2-hour intervals during course of the work thereafter. Test by Ring and Ball Test, ASTM D2398, or similar recognized test method. Submit samples to independent laboratory for testing or perform tests in field, at Contractor's option.
F. Warranty - Manufacturer's Certification, Bulk Bitumen: Submit manufacturer's certification indicating that bulk bituminous materials (if any) delivered to project comply with required standards. Include quantity, statistical and descriptive date for each product. Submit certificate with each load before it is used.
- Include continuous log showing time and temperature for each load of bulk bitumen, indicating date obtained from manufacturer, where held and how transported prior to final heating and application on roof.
1.05 QUALITY ASSURANCE
A. Manufacturer Qualifications: Provide primary products, including each type of roofing sheet (felt), bitumen, composition flashings and vapor retarder, produced by a single manufacturer, which has produced that type product successfully for not less than 3 years. Provide secondary products only as recommended by manufacturer of primary products for use with roofing system specified.
B. Installer Qualifications: A single Installer (&quo= t;Roofer") shall perform the work of this section; and shall be a firm with not less than 5 years of successful experience in installation of built-up roofing systems similar to those required for this project and which is acceptable to or licensed by the manufacturer of primary roofing material.
- Installer Certification: Obtain written certification from manufacturer of built-up roofing system certifying that installer is approved by manufacturer for installation of specified roofing system. Provide copy of certification to Contracting Officer prior to award of roofing work.
- Installer's Field Supervision: Installer must maintain full-time supervisor/foreperson on jobsite during times that roofing work is in progress. Supervisor must have minimum of 5 years experience in roofing work similar to nature and scope of specified roofing.
C. Pre-Application Roofing Conference: Approximately two weeks prior to scheduled commencement of built-up roofing installation and associated work, meet at project site with Installer, installer of each component of associated work. Lifters of roof-top units and other work in and around roofing which must precede or follow roofing work (including mechanical work), the Contracting Officer, Government, roofing system manufacturer's representative, and other representatives directly concerned with performance of the work including (where applicable) Government's insurers, test agencies, and governing authorities. Record (Contractor) discuss= ions of conference and decisions and agreements (or disagreements) reached, and furnish copy of record to each party attending. Review foreseeable methods and procedures related to roofing work, including but not necessarily limited to the following:
- Tour representative areas of roofing substrates (decks), inspect and discuss condition of substrate, roof drains, curbs, penetrations and other preparatory work performed by other trades.
- Review roofing system requirements (drawings, specifications and other contract documents).
- Review required submittals, both completed and yet to be completed.
- Review and finalize construction schedule related to roofing work and verify availability of materials, Installer's personnel, equipment and facilities needed to make progress and avoid delays.
- Review required inspection, testing, certifying and materials usage accounting procedures.
- Review weather and forecasted weather conditions, and procedures for coping with unfavorable conditions, including possibility of temporary roofing (if not a mandatory requirement).
D. Compatibility: All materials provided shall be compatible with each specified component of the built-up roofing system. All materials shall be approved by the manufacturer of the roofing materials for use with this system.
E. UL Listing: Provide built-up roofing system and component materials which have been tested for application and slopes indicated and are listed by Underwriters' Laboratories, Inc. (UL) for Class A external fire exposure.
- Provide roof covering materials bearing Classification Marking (UL) on bundle, package or container indicting that materials have been produced under UL's Classification and Follow-up Service.
E. FM Listing: Provide built-up roofing system and component materials which have been evaluated by Factory Mutual System for fire spread, wind-uplift, and hail damage and are listed in "Factory Mutual Approval Guide" for Class I construction.
- Provide roof covering materials bearing FM approval marking on bundle, package or container, indicating that material has been subjected to FM's examination and follow-up inspection service.
F. Condition of Surfaces: Decks to which roofing system is to be applied shall be sound, dry, including flute openings of metal decks, clean, smooth, and free from projections. Application of roof system components shall not progress when there is ice, frost, surface moisture, or dampness visible on the roof deck. The Contractor shall be responsible for damage to the deck or structure due to his trafficking across same, or to loads imposed by him in any form. Evidence shall be submitted that roof deck surfaces, and all slopes to roof drains and outlets have been checked, and are approved, for installation of the roof system before installation of any roofing is started. Joints in deck shall be sealed as necessary to prevent drippage of bitumen into the building or down exterior walls.
1.06 DELIVERY, STORAGE AND HANDLING
A. Packing and Shipping: Roofing materials shall be delivered with manufacturer's labels and seals intact and legible. Materials delivered in bulk shall be accompanied by a certificate from the manufacturer, stating that the material complies with the specified requirements.
B. Storage and Protection:
- Store and handle roofing sheets in a manner which will ensure that there is no possibility of significant moisture pickups. Store in a dry, well ventilated, weather-tight place. Unless protected from weather or other moisture sources, do not leave unused felts on the roof overnight or when roofing work is not in progress. Store rolls of felt and other sheet materials on end on pallets or other raised surface. Handle and store materials or equipment in a manner to avoid significant or permanent deflection of deck.
- Use forklift cradle to lift insulation pallets to roof deck; do not use sling. No more insulation shall be stored on the roof than can be used in one day.
- Felt rolls and insulation piles which are stored on roof overnight shall be covered with tarpaulins, not plastic. Coverage shall be complete, with tarpaulins extending to bottom to prevent exposure in wind. Material shall be stored in such a manner so as not to exceed 20 PSF loading on roof.
C. Mineral Aggregate: The aggregate shall be delivered in dry condition. If yard gravel is wet, it may be oven dried at an asphaltic batching plant. Aggregate piles at site shall be completely covered with tarpaulins.
1.07 PROJECT/SITE CONDITIONS
A. Environmental Requirements:
- Proceed with roofing work only when existing and forecasted weather conditions will permit work to be performed in accordance with manufacturer's recommendations and warranty requirements.
- Roofing system materials shall not be applied during rain or snow. Applications may be continued in cold weather subject to the following requirements:
- Comply with all provisions of these and the manufacturer's specifications.
- Do not overheat bitumen to compensate for rapid chilling.
- When temperature drops below 40 degrees F., use insulated buckets to carry hot bitumen; mop manually no further than 5 feet in front of felt rolls and immediately unroll felt over bitumen; immediately apply top pour of bitumen and aggregate before stored head dissipates in the membrane.
B. Temporary Protection: Contractor shall be responsible for protection of spaces and contents below roof deck from water leakage. Roof deck shall never be left exposed overnight or during inclement weather.
C. The contractor shall be responsible for protection of spaces and contents below roof deck from water leakage. Roof decks or insulation shall never be left exposed overnight or during inclement weather. Temporary membranes with open seams, such as plastic or loose roofing felts, shall not be used to provide protection.
A. Special Project Warrantee: Submit 2 executed copies of standard 2 year "Roofing Guarantee" on form included at end of this section, covering work of this section including roofing membrane, composition flashing, roof insulation, vapor barriers (if any), and roofing accessories, signed and countersigned by Installer (Roofer) and Contractor.
B. Manufacturer's Warranty: Submit executed copy of roofing manufacturer's standard "Limited Service Warranty" agreement including flashing endorsement, signed by an authorized representative of built-up roofing system manufacturer, or on form which was published with product literature as of date of contract documents, for the period of 10 years after date of substantial completion.
C. Defects: Conditions which may be detrimental to completion or performance of specified work shall be reported in writing to the Contracting Officer prior to commencing such work and such work shall not start until defects have been corrected. No claim by the Contractor concerning defects will be allowed if made after starting work.
A. Insurance and Code Requirements: Provide materials complying with governing regulations, and which can be installed to comply with the following:
- Factory Mutual requirements for "Class I" or "Noncombustible, including zoned wind resistance.
- Underwriter's Laboratories "Fire Classified" and "Class 60" wind uplift resistance.
B. All material used shall be asbestos free.
C. Temporary Roofing Membrane: 2 plies perforated No. 15 asphalt saturated organic felt complying with ASTM D226, Type I, set in and glaze-coated with hot mopping of ASTM D312, Type III asphalt.
D. Vapor Barrier (Retarder):
- Bituminous Vapor Barrier (Retarder): 2 plies perforated No. 15 asphalt saturated organic felt complying with ASTM D226, Type I, 1st layer nailed, 2nd layer set in and glaze-coated with ASTM D312, Type III Asphalt.
E. Roof Insulation:
- Tapered Rigid Board Insulation: Boards shall be 24" wide, the tapering system composed of boards having a slope of AC" and AB" per foot. Installation shall be in accordance with manufacturer's specifications, using type III asphalt. Junctures at valleys shall be mitred (not laced). Contractor shall furnish roof plan drawings showing all slopes and valleys details. Otherwise same as paragraph "2" below.
- Glass-Fiber Board Roof Insulation: Rigid glass-fiber boards of thicknesses indicated, with k-value of 0.27 at 75 F (24 C), with integrally bonded top covering of asphalt-impregnated felt or Kraft paper; comply with ASTM C726; manufacturer's standard sizes except as otherwise indicated. Provide for flat and tapered installation.
F. Built-Up Roof Membrane System:
- Nailable-Deck Asphalt/Glass-Fiber/Aggregate Roofing (NAGA-BUR): Provide built-up, aggregate-surfaced roof system with asphalt bitumen and glass fiber ply felts for lay-up as indicated:
- Sheathing Paper: Single-ply of 5-pound rosin- sized sheathing paper.
- Ply Felts: 4 plies of asphalt-impregnated glass= -fiber felts, complying with ASTM D2178, Type IV.
- Interply Bitumen: Roofing asphalt, complying with ASTM D312, Type III.
- Comply with NRCA Roofing and Waterproofing Manual, Specification Plate No. 32 - NAGA, Diagram A.
- Insulated-Deck Asphalt/Glass-Fiber/Aggregate Roofing (IAGA-BUR):
- General: Provide built-up aggregate-surfaced roof system with asphalt bitumen, and plies glass-fiber mats for lay-up as indicated.
- Primer: asphalt cut-back primer, complying with ASTM D41.
- Ply Felts: 4 plies of asphalt-impregnated glass-fiber mats, complying with ASTM D2178, Type 2178.
- Bitumen: Roofing asphalt, complying with ASTM D312, Type III.
- Comply with NRCA Roofing and Waterproofing Manual, Specification Plat-#42- IAGA, Diagram A.
G. BUR Edge/Penetration Materials:
- Roofing Cement: Asphaltic cement; comply with ASTM D2822. Asphaltic cement shall be reinforced with non-asbestos fibers, imparting positive properties equal to the asbestos fibers. The Contractor shall submit to the Contracting Office the following information from the roofing cement manufacturer: Reports of laboratory performed weatherometer tests, indicating an expected life span for the fibrous, non-asbestos cement equal to the span for ASTM conforming asbestos fiber cement similarly tested; in No case shall it be less than a 15 year span. Roof work shall not proceed until such Test Reports are submitted.
- Glass Fiber Fabric: 1.5-lb. (min.) sheet, of woven glass fiber, impregnated with asphalt (ASTM D1668).
- Coated Felt: 26-lb. Sheet, of asphalt-organic felt coated with asphalt both faces, "No. 30 Coated Organic Felt."
- Lead Flashing: 4-lb. Sheet of common desilverized pig lead.
- Modified Bitumen shall be modified by the addition of styrene-butadiene-styrene (SBS), reinforced. It shall be mopped on.
H. Miscellaneous Materials:
- Surfacing Aggregate: Clean, water-worn opaque gravel complying with ASTM D1863.
- Where ASTM D1863 aggregate is not available, provide aggregate complying with gradation sizes 6, 7, and 67 of ASTM D448, provided that moisture content by weight is 3% or less and aggregate meets other requirements of ASTM D1863= .
- Wood Member's Units: Provide wood pressure treated with water-borne preservatives for above ground use (AWPB LP-2).
- Insulation Joint Tape: 6" or 8" wide coated glass fiber mat.
- Mastic Sealant: Polysiobutylene (plain or bituminous modified), nonhardening, nonmigrating, nonskinning and nondrying= .
- Asphaltic Primer: Comply with ASTM D41.
- Fasteners: Provide industry-standard types of mechanical fasteners for BUR system work, tested by manufacturer for required pull-out strength where applicable and compatible with deck type and roofing products used. Provide either 1" diameter nail heads or 1-3/8" diameter x 30-gauge sheet metal caps for nails used to secure base sheets, felts, or insulation boards of roofing system. Material shall be galvanized or stainless steel.
2.03 FABRICATION OF SHEET METAL ACCESSORIES:
A. SMACNA and NRCA Details: Conform work with details shown, and with applicable fabrication requirements of "Architectural Sheet Metal Manual" by SMACNA. Comply with installation details of "Roofing and Waterproofing Manual" by NRCA and Section 07600.
B. Prefabricate units as indicated, or provide standard manufactured units complying with requirements; fabricate from sheet metal indicated or, if not otherwise indicated, from copper.
C. Provide 4" wide flanges for setting on BUR membrane with concealment by composition stripping as per General Notes on the Drawings.
D. Fabricate work with stitch riveted soldered joints and seams; except where joint movement is necessary, provide 1-inch-deep interlocking hooked flanged filled with mastic sealant.
E. Fabricate gravel "rings" and aggregate divider strips with 1" high standing leg of folded sheet metal, notched form top with 5/8" V notches. Space notches 3" o.c. where strip intersects flow of water on roof. Fabricate rings to sizes and shaped indicated (but not less than 36" square).
F. Fabricate penetration sleeves with minimum 8" high stack, of diameter 1" larger than penetrating element. Counter flashing is specified as work of another section of these specifications.
A. Verification of Conditions:
- Examine substrate surfaces to receive built-up roofing system and associated work and conditions under which roofing will be installed. Do not proceed with roofing until unsatisfactory conditions have been corrected in a manner acceptable to Installer.
- 2. Verify that deck is securely fastened with No projecting fasteners and with No adjacent units in excess of 1/16" out of plane.
B. Condition of Surfaces: Decks to which roofing system is to be applied shall be sound and dry, clean, smooth and free from projections. Application of roof system components shall not progress when there is ice, frost, surface moisture, or dampness, visible on the roof deck. Joints in deck shall be sealed as necessary to prevent drippage of bitumen into the building or down the exterior walls. Deck shall be thoroughly broomed clean, including within flutes.
A. General: This work includes, without limitation, removal of existing roofing, insulation, flashings, wood blocking and equipment pads in areas shown on the drawings.
- Any exposed surface of the precast concrete units shall be dried of water and cleaned of loose material.
- Any disintegrating, wet or failed material shall be removed.
- Any cracks, minor holes, or other surface imperfections of the precast concrete units supporting surface shall be repaired as per Drawings General Notes.
- Removed roofing, insulation, and flashing will be removed from the roof immediately without allowing accumulation of piles of trash. Tossing of any trash, tools or any objects from roof to any areas below, including from one roof level to another, is expressly prohibited.
- Removed materials shall become the property of Contractor and shall be removed from the site. Debris and scrap shall be removed from the work area daily.
B. Protection: Protect other work from spillage of built-up roofing materials, and prevent liquid materials from entering or clogging drains and conductors. Replace/restore other work damaged by installation of built-up roofing system work.
C. Surface Preparation: Before any tear off of the existing BUR systems, remove all gravel with a mechanical broom and a mechanical vacuum.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Fire and Wind Resistance Compliance: Install BUR system for compliance with the following:
- Factory Mutual requirements for "Class I" or "Noncombustible, including zoned wind resistance as specified by FM.
- Underwriter's Laboratories "Fire Classified" and "Class 60" wind uplift resistance.
B. Coordinate the installation of insulation, roofingsheets, flashings, stripping, coatings and surfacings, so that insulation and felts are not exposed to precipitation nor exposed overnight. Provide cut-offs at end of each day's work. To cover exposed felts and insulation with a course of coated felt with joints and edges sealed with roofing cement. Remove cut-offs immediately before resuming work. Glaze coat installed ply-sheet courses at end of each day's work where final surfacing has not been installed.
C. Asphalt Bitumen Heating: Heat and apply bitumen in accordance with equiviscous temperature method ("EVT Method") as recommended by NRCA. Do not raise temperature above minimum normal fluid-holding temperature necessary to attain EVT (+25 F or 40 C at point of application) more than one hour prior to time of application.
Discard bitumen which has been held at temperature exceeding finished blowing temperature (FBT)for a period exceeding three hours.
Determine flash point, finished blowing temperature and EVT of bitumen, either by information from bitumen producer or by suitable tests, and determine maximum fire-safe handling temperature and do not exceed that temperature in heating bitumen; but in No case heat bitumen to a temperature higher than 25 F (14 C) below flash point.
For aggregate-surfaced pour coats of bitumen, limit application temperature to minimum required for proper embedment of aggregate and maximum which will permit retention of a coating of weight required (depends on slope of surface). Keep kettle lid closed except when adding bitumen.
- Contractor shall maintain not less than 2 testing thermometers similar to Aeroil dip bimetallic type with a dome faced gauge registering 50 F at the kettle site at all times. Built-in asphalt heating plant thermometers shall not be used in lieu of testing thermometers.
- Heating of Bitumen:
- Solid bitumen shall be broken open on a clean