Amendment 0003 - Q-A.pdf

GSA Northeast and Caribbean Region

U.S. General Service Administration

One World Trade Center

New York, NY 10007 www.gsa.gov

March 4, 2020

Amendment No. 0003

Request for Proposal No.: 47PC0220R0008

Construction Contract for: Pirnie Upper Envelope of Bldg - Construction

This Amendment No. 0003 is being issued to provide GSA response to RFIs received as listed below:

Question No.

Spec Section / Drawing #

Question & Response / Clarification

1 8/AE502 How is the top sheet of the 3/4" CDX to be attached on the mansard roof sections?

Response: Top sheet is to be fully adhered using adhesive layout shown on Drawing AE101 Detail 2 (4" bead spacing)

2 3/AE503 Detail is titled "Detail 2." Could the correct reference be provided?

Response: REPLACE the words "Detail 2" with " ABANDONED SKYLIGHT

INFILL EDGE DETAIL - TYPICAL"

3 075423

3.5.3 ;

9/AE501

Paragraph states mechanical attachent of the first layer of insulation.

Detail 9/AE501 shows adhesive for all insulation layer, and no fasteners.

Response: System shall be fully adhered.

4 076200 2.2.;

9/AE502 ;

AE101

Clarify the underlayment materials desired for installation underneath the Yankee gutter system. Specification outlines TPO membrane as an option, along with 30 lb. felt or a high temperature self-adhering membrane. Detail 9 on Sheet AE502 calls out "Yankee gutter drain, refer to plumbing drawings with clamp ring for TPO liner." Basis of design note on drawing AE101 says "install TPO liner under copper gutter." Please advise on whether or not the high temperature self-adhering membrane will be acceptable for installation underneath the copper gutter liner.

Response: The design intent is to provide the Self-Adhering, High-Temperature Sheet membrane (Section 076200, 2.2C) under the copper gutter as shown on Detail 9 / Sheet AE502

5 6/AE501 ;

7/AE501

Pipe penetration (6/AE501) has wood blocking around the penetration, while the tie-off penetration (7/AE501). Will wood blocking be required around penetrations following 7/AE501 as well?

One World Trade Center

Response: Tie-Off Detail 7 on Drawing Sheet AE501 shows a welded connection to the existing steel member so wood blocking in not required. ADD note

"CONNECTION TO BE WELDED"

6 AE101 Basis of Design for snow guards: Information on drawings calls for three rows of snow guard rail fences on all mansard roofs. The existing roof has only on row of snow fence, and the roof plan for the new work shows one row. Please clarify how many rows of snow guards are required.

Response: Only one row of snow guard is indicated/required; however, it is a three-bar system.(possible cause of confusion?)

7 4/AE310 ;

6/AE502;

AD101

Detail 4/AE310 shows the freight elevator roof deck to be a wood deck that gets replaced with new (also in detail 6/AE502 which shows the enlarged detail view). Drawing AD101's Demo Plan keyed note #4 has these roofs as existing concrete deck that does not get removed. Please advise as to which one is correct?

Response: Existing roof at elevator penthouses is a concrete deck, not wood.

8 75423 Confirm that the existing structures provide slope for the roofs and that no tapered insulation is required. The details do not show or call out tapered insulation nor does the insulation increase in thickness, but the specifications call for tapered insulation at 1/4" per foot.

Response: Tapered insulation is only required for crickets at roof top obstructions to divert water around the obstruction to the roof drains. The structural members are sloped as observed and documented on existing drawings.

9 AE101 ;

10/AE503

; 9/AE503

; 075423 2.4.

AE101, Keyed Note #1 calls for a torched down vapor barrier at all roof areas as Roof Type 1. Detail 10/AE503 callsf or a torched down vapor barrier at the Middle Roof at the south parapet of the roof. Detail 9/AE503 calls for a torched down vapor barrier at the Upper Roof along column line E. All other details call for peel and stick vapor barrier.

The spec calls for a peel and stick vapor barrier, with no mention of a torch down vapor barrier. Paragraph indicates to "refer to Self-Adhering Vapor Retarder Section of Specification." There is no specific vapor retarder section in the specification. Please provide the specification section, and please clarify the approach.

One World Trade Center

Response: The torch applied product basis of design (BOD) is: GAF Materials Corporation; Ruberoid Torch.

Torch applied modified bitumen membrane for Vertical Applications:

0.160” (4 mm) thick, uniform, flexible sheets with polyester mat core, having the following physical properties:

1) Tensile Strength @0F (nom.), lbf/in; 90 minimum; ASTM D 5147.

2) Elongation @ 0F (nom.), %; 45; ASTM D 5147

3) Low-Temperature Flexibility (max), F: 7; ASTM D 5147

4) Tear Strength (nom.), lbf; 98; ASTM D 5147

5) Dimensional Stability, %; <1; ASTM D 5147

10 1, 8 &

9/AE502

Are "as-built" drawings available to indicate how the existing Yankee gutter system is constructed?

Response: The A/E firm utilized a partial set of as-built documents stored in the building by the GSA.

11 AE101 ;

1/AE310

Drawing AE101 shows the mansard flat roofs as hipped sloping structures. 1/AE310 shows a cross section of a portion building edge at Column Line E. Are structural drawings available to show the current position and elevations of the existing flat roof steel purlins?

Response: The A/E firm utilized a partial set of as-built documents stored aim the building by the GSA.

12 Question: Will other GSA PPQs that have been filled out by COs and COTRs, and completed within the last year, be acceptable for submission in lieu of sending out new ones for the proposal's Past Performance section?

Response: Yes, other GSA Past Performance Questionnaires (PPQs) that have been filled out by COs and COTRs, and completed within the last year, shall be acceptable for submission in lieu of sending out new ones for the proposal's Past Performance section.

Previous past performance questionnaires are acceptable provided they meet the minimum requirements, i.e. projects completed with the past duration of time stated within the solicitation.

Since the vendor is saying that they have PPQs completed within the last year, it will be acceptable.

13 6/AE310 Will any interior finishes be required at the skylight infill locations? If so, please provide materials and requirements.

Response: No interior finishes are intended for skylight infill areas.

14 6/AE310 Are as-built drawings available to show the construction of the skylight curbs?

One World Trade Center

Response: Limited as-builts are available from GSA stored at the building.

15 7/AE502;

8/AE502;

9/AE502

Note "Interface between existing structural steel and schedule wood deck is to receive paint where dissimilar materials contact one another" seems to indicate that painting of the structural steel surfaces will be required only where the wood deck comes in to contact with steel.

Please confirm that it is not the intention of the project design to paint all structural steel found in the attic space.

Response: The intent is that painting of the structural steel surfaces will be required only where the wood deck comes in to contact with steel.

16 7/AE502;

8/AE502;

9/AE502

Would #15 felt or red rosin paper be an acceptable bond breaker between the wood and structural steel?

Response: If the contractor is talking about the interface between existing structural steel and scheduled wood deck, then the design intent is to receive paint where dissimilar materials contact on another. Covering the locations between the wood deck and the structural steel with felt would not meet the design intent to seal/ protect the steel from moisture oxidizing it at contact points.

17 055000 2.2; 2.5

Ladder materials specified in Section 055000 include aluminum and steel. Please clarify the desired materials.

Response: Ladder materials should be aluminum only.

18 075900;

AE101

General Roof Plan Notes #12

Please advise specifically where this testing will occur. Please advise what roof deck types this testing will occur over.

Response: The specific location that will be tested will be selected at the time of testing by the Project Manager at GSA. All roof decks types in all zones will be tested to their recommended windup lift after construction work is completed

19 075423;

2.5

Can 25 PSI Polyisocyanurate roof insulation of same overall R-value be used instead of the specific polystyrene roof insulation?

Response: Polyisocyanurate insulation is not acceptable.

20 075423;

1.3.D;

2.1.D;

2.1.E.

Different performance requirements are found in each paragraph. 1.3.D

- calls for FM 1-90 rating. 2.1.D - calls for FM 1-60 rating. 2.1.E calls for SPRI 105 psf wind load capacity. As the written specification does not clearly list what requirement should be met, please clarify. Please also confirm that a Class 1 system is desired. If so, it appears that the insulation system will need to be polyisocyanurate.

One World Trade Center

Response: The specification refers to all the calculated wind uplifts for the various roofs. Detail 2 on drawing sheet AE101 indicates the requirement for installation and adhesive bead spacing.

21 075423 1.9.B.1.

Paragraph specifies a 10 year roofing installer's warranty. Bonding companies will not write coverage for 10 years. The industry standard is 2 years. Please confirm that industry standard 2 year roofing installers warranty will be acceptable on this project.

Response: Contractor shall provide stated warranties. This warranty requirement has been requested and successfully provided by contractors on past roof projects at Binghamton FB; Foley Courthouse; Hanley FB; and Keating FB

22 Floor Plan Keyed Notes 2 &

3 AE101

Notes reference "S.I.P." which we are assuming means Structural Insulated Panel (not found on the abbreviations page). Is this to be a premanufactured panel? If so, please provide the materials requirements.

Response: No structural insulated panels (SIP) are specified for this work - DELETE reference to S.I.P.

23 061600 2.6.

Paragraph 2.8 calls out adhesive for field gluing panels to wood framing. Please provide information as to where this work is required.

Response: This work occurs in the attic space at the yankee gutter reconstruction.

24 075423 2.4.A.;

AE101

Keyed Notes #1

The only type of vapor barrier found in the specifications is self-adhered. Note on Sheet AE101 calls out a torch applied vapor barrier.

Please provide specific requirements.

Response: The torch applied product basis of design (BOD) is: GAF Materials Corporation; Ruberoid Torch.

Torch applied modified bitumen membrane for Vertical Applications:

0.160” (4 mm) thick, uniform, flexible sheets with polyester mat core, having the following physical properties:

1) Tensile Strength @0F (nom.), lbf/in; 90 minimum; ASTM D 5147.

2) Elongation @ 0F (nom.), %; 45; ASTM D 5147

3) Low-Temperature Flexibility (max), F: 7; ASTM D 5147

4) Tear Strength (nom.), lbf; 98; ASTM D 5147

5) Dimensional Stability, %; <1; ASTM D 5147

25 3/AE503 Detail calls out "2 layers 1/2" Concrete Protection Board." We do not see any products call out in the specification. Please provide information on the materials to be used in this location.

One World Trade Center

Response: Provide Protection Board: ASTM C 1177/C 1177M, glass-mat, water-resistant gypsum substrate, 1/2 inch (13 mm) thick, minimum. Thickness required shall depend upon ensuring a positive slope is maintained to properly drain the roof. Product: Subject to compliance with requirements, provide "Dens-Deck" by Georgia-Pacific Corporation.

26 AE101,

Basis of Design Descriptio n, Bullet 1

Basis of Design, Lower Roof. Outlines that the wood deck is to be removed, but then indicate to patch openings in the concrete deck.

2/AD101 is showing the deck in this area as concrete. Please clarify the deck construction for the Lower Roof.

Response: An existing raised wood deck structure is constructed on top of the existing concrete deck. This wood structure is called out to be demolished down to the concrete deck.

27 AE101,

Basis of Design Descriptio n, Bullet 3

Basis of Design, Middle Roof. Outlines that the wood deck is to be removed. 2/AD101 is showing the deck in this area as concrete. Please clarify the deck construction for the Middle Roof.

Response: An existing raised wood deck structure is constructed on top of the existing concrete deck. This wood structure is called out to be demolished down to the concrete deck.

28 075423 3.5.C.

Is this paragraph to be followed for attaching the insulation over the wood decks on the steep sloped mansard roofing sections? No specific insulation installation requirements were found in sections 061600 or 072100 for the steep sloped mansard roof systems. The drawings seem to indicate that all layers are to be adhered. We are concerned with only adhering insulation on the deck that is sloped 8 in 12. Will mechanical attachment of the insulation and plywood system on the steep sloped mansards roof sections be considered? Or, will additional insulation stops be required up the slope, as there is only one in the system at the eave of the roof.

Response: Additional insulation stops may be required to secure the insulation.

29 075423

3.4. ;

9/AE501

Section has installation requirements for a substrate board, but no products are specified in Part 2. Typical roof construction details do not show a substrate board. Please advise.

Response: Provide Cover Board: ASTM C 1177/C 1177M, glass-mat, water-resistant gypsum substrate, 1/2 inch (13 mm) thick, minimum. Thickness required shall depend upon ensuring a positive slope is maintained to properly drain the roof. Product: Subject to compliance with requirements, provide "Dens-Deck" by Georgia-Pacific Corporation.

One World Trade Center

30 075423 3.5.C.

Specification outlines the insulation attachment over wood decks, but does not provide installation requirements over a concrete deck. Please provide specifics for installation over the concrete roof deck sections.

Response: Installation method is the same for concrete deck.

31 Question: Will other GSA PPQs that have been filled out by COs and COTRs, and completed within the last year, be acceptable for submission in lieu of sending out new ones for the proposal's Past Performance section?

Response: Yes, other GSA Past Performance Questionnaires (PPQs) that have been filled out by COs and COTRs, and completed within the last year, shall be acceptable for submission in lieu of sending out new ones for the proposal's

Past Performance section.

Previous past performance questionnaires are acceptable provided they meet the minimum requirements, i.e. projects completed with the past duration of time stated within the solicitation.

Since the vendor is saying that they have PPQs completed within the last year, it will be acceptable.

32 Question: Electronic Leak Detection.

Specification section 075900 - Electronic Leak Detection (ELD) – Low

Voltage Vector Mapping part 1 General, subpart A reads as follows:

Engage an Independent Testing Agency to provide a Certified ELD Technician to perform Electronic Leak Detection to verify that membrane is free of any holes, open seams or capillary defects that will allow water to pass. Electronic

Leak Detection shall include:

Low Voltage Vector Mapping Survey for roofing and waterproofing membranes.

When required, a permanent Electronic Leak Detection System

(ELDS) for roofing and waterproofing membranes.

Question - Please indicate that a permanent Electronic Leak Detection System is required for this project and if in fact one is required, please provide a detail and specifications.

Response: CHANGE the word “When” to “Not”.

33 Question: Disruptive work

On drawing G-002, General notes 4 reads as follows:

4- Noise Level: Noisy work that disrupts building operations shall be performed outside of normal working hours, refer to specifications for more information.

Specification section 011400 Work Restrictions part 1.3 working hours, One World Trade Center subpart D reads as follows:

D. Contractor’s required working hours: The following work shall be performed during Government Unoccupied hours:

1. Noisy and/or odor-producing work that may disrupt tenant operations in adjacent spaces.

2. Any work that disrupts the mission of any building tenant.

Question - Will the contractor be permitted to perform the roof demolition and installation during normal business hours?

Response: Contractor is permitted to perform any and all work that does not disrupt tenant operations. How and what means a contractor uses to perform the work

(demolition and installation) are up to the contractor. It can be stated that based on past Upper Envelope Projects demolition and installation have occurred during normal business hours with some exceptions which past contractors were able to overcome and avoid disruptions by adjusting where and when certain activities took place combined with providing advance notification and coordinating activities with GSA aided in minimizing potential disruptions.

34 Question: Snow Guards

Provide design guidelines for the snow guards as far as loads to design for. In lieu of guidance, we would design for the roof plan vector of the weight of the full snow load with zero friction factor without consideration for impact from sliding snow.

Response: The suggestion proposed is an acceptable guideline for snow guard provisions.

35 Question: Roof Curbs

Question # 1. The roof curbs seem to sort of defer back to someone else to prove they work. Are stamped drawings or calculations required for roof curbs?

Question # 2. Working from the top down: roofing, ¾” plywood, 2 layers of

3” foam, ¾” plywood, 2x6 decking. There seems to be no fastening between the plywood layers through the insulation. There is one note we found that mentions SIP panels, but the fact that you are asking for 2 layers of insulation is contrary to that. We would need to understand that mechanism this roof uses to resist wind uplift and even keeps the upper plywood from sliding downwards before we can address the snow guard design.

Response: Answer #1: Stamped drawings are not required for roof curbs.

Answer #2: Details 7 & 8 on sheet AE502 indicates anchorage required via fully adhered system using Detail 2 Note #5 on sheet AE10

One World Trade Center

Amendment Impact: Clarification and Correction of Project Drawings / Specification and Bid

Requirement

Basis: Incorporating Pre-Bid RFI Responses and Clarification of Bid Valid Until Date

Drawing # AE101

Although only one row of snow guard is indicated the actual requirement is for a three-bar system.

Drawing # 3/AE503

REPLACE the words "Detail 2" with " ABANDONED SKYLIGHT INFILL EDGE DETAIL -

TYPICAL"

Drawings # 6/AE501 and 7/AE501

Tie-Off Detail 7 on Drawing Sheet AE501 shows a welded connection to the existing steel member so wood blocking in not required. ADD note "CONNECTION TO BE WELDED"

Specification Section # 075900 Electronic Leak Detection (ELD) – Low Voltage Vector

Mapping

Under Part 1.A.2 CHANGE the word “When” to “Not”

Thus Part 1.A.2 shall read as follows:

When Not required, a permanent Electronic Leak Detection System (ELDS) for roofing and waterproofing membranes.

Clarification of Bids Remain Valid Until Timeframe

Bidders are asked to provide and state that bids shall remain valid for 90 days from date of submission

Section 011000 – Summary Section 1.2 G. states that “If any of the Option Work is awarded by the Government, it will be awarded at the same time that the Base Bid Work is awarded.”

This Section 011000 – Summary Section 1.2 G. is being revised to read as follows:

If any of the Option Work is awarded by the Government, it may be awarded within 90 days from date of submission of your proposal.

One World Trade Center

Should you have any questions, please contact me at (212) 577-8681 or jayshree.tank@gsa.gov.

Please acknowledge receipt of all amendments with your offer submission.

Sincerely, Jayshree Tank

Contract Specialist

Acquisition Management Division

GSA, Northeast and Caribbean Region

One World Trade Center

New York, NY 10007- 0089

E-mail: jayshree.tank@gsa.gov

(212) 577-8681