RFI Responses.pdf

RFI Responses - Solicitation 697DCK-22-R-00018

This document contains clarifications to questions submitted to the Contracting Officer during the pre-bid site visit for the project listed above.

The following specification sections were modified and included in a revised set of specifications dated January 31, 2022:

SPECIFICATIONS CLARIFICATION OR CHANGE

Section 01 10 00 Removed exhaust fan E10 from scope of work.

Section 07 01 50.19 Highlighted requirement stating contractors are responsible for temporary roofing.

Section 07 57 00 Coated foamed roofing added to specifications. Use only where indicated.

Section 07 84 13 Penetration firestopping added to specifications. Use only where indicated.

Section 23 35 00 3.2C Removed references to sections 23 34 13 and 23 34 16.

Section 23 35 33 3.2K Removed reference for 09 22 116.23 Gypsum Rated Assemblies.

Section 23 38 13 1.6C Removed seismic qualification data.

Section 23 38 13 3.2G Removed seismic qualification data.

Section 23 34 23 Removed references for seismic design and restraints (1.3.B.4)

The following drawings were updated with clarifications and dated January 31, 2022:

DRAWING CLARIFICATION OR CHANGE

ZHU-D-ARTCC-M119-A

Added text and deleted E10 from scope.

ZHU-D-ARTCC-M074-A

Added callout to Engine Generator roof exhaust.

ZHU-D-ARTCC-M117-A

Added missing callouts for clarity to building-A roof plan.

ZHU-D-ARTCC-D025-A Added clarifications to scope.

ZHU-D-ARTCC-D026-A Added clarifications to scope.

ZHU-D-MOD4-M308 For information only; location of EF-403. Contractor must refer to Refer to drawing ZHU-D-ARTCC-M119-A and specifications for performance requirements.

ZHU-D-ADMIN-M046 For information only. Exhaust fan is located in Building-B south attic.

Contractor must replace exhaust in its entirety. Do not disturb roof hood and ductwork.

ZHU-PSM-M05-01 For information only; location of EF-510 and E12. Aid to contractors for exhaust fan location within to building-A.

ZHU-D-ADMIN-M040 For information only; location of EF-14. Aid to contractors for exhaust fan location within to building-A and building-B.

ZHU-DSR-M80 For information only; Exhaust Fan BEX-1 is in scope, drawing added to help locate fan relative to the existing buildings. Refer to drawing ZHU-D- ARTCC-M119-A and specifications for performance requirements.

ZHU-D-ADMIN-M045

For information only; Exhaust Fans AEX-1 and AEX-2 are in scope, drawing added to help locate fans relative to the interior of the building (kitchen area). Refer to drawing ZHU-D-ARTCC-M119-A and specifications for performance requirements.

Exhaust Fan Photographs

Pages 10 through 15 at the end of the attachments depicts those exhaust fans above building-A, and can be compared against the modified drawings. These pictures depict the material, type and condition of the fans. Contractor must refer to Refer to drawing ZHU-D-ARTCC-M119-A and specifications for performance requirements.

The revised specifications and drawings in this amendment to solicitation have addressed concerns and questions surfaced below. Please refer to the revised specifications and the engineer’s response for more information.

Item 1 Site visit presentation and full size drawings:

a) Can we please be sent a copy of the presentation and a copy of the full size drawings?

Response: Presentation was for informational purposes and internal use only, it was an aid during the pre-bid. Hard copies of drawings will not be sent. If the Contractor requires full size printed drawings, they will need to contact a commercial printing service.

Item 2 Exhaust fans project clarification: Do you know/ can you find out what the controls system for the building is or if its open protocol? If they have a specific control system, we will have to use them. If it’s an open protocol, we may be able to use our controls techs in house.

Response: The facility has a building automation system (BacNet) by Schneider Controls; it is not an open protocol. The as-built drawings for the control system are included with this amendment.

Item 3 Clarifications for Building A Roof and Exhaust fans questions:

a) It does not say in the plans but are we needing any back draft dampers or motorized dampers?

Any special coatings on the units?

b) Are there specs or cut sheets on the units? We need to verify sizes of existing units to account for possible curb adapters.

c) I assume the fans are running off existing VFDs? Are those being replaced?

d) Has there been a core sample completed on the roof? I have read over all documents and have found no literature on this topic.

1. We can provide the proposal with what we would recommend being replaced with as far as ISO board, insulation, nails, etc.

e) Can the exhaust fans be installed one at a time?

1. The reason this is necessary knowledge is that we may have to pack in/out a crane, and this could get very costly, and I don’t want to over or under budget this expense.

Response: a) Motorized and back raft dampers are specified in 23 34 23 page 3, 2E. A corrosion resistant epoxy coating or galvanized steel with 4ml thick coating of polyvinyl coating inside and out would be acceptable. AEX-1, AEX-2, AEX-4, have no dampers. Exhaust fan BEX-2 has motorized dampers. Only exhaust fan BEX-1 has back draft dampers installed on the exhaust fan. The exhaust fans in the EG Building have back draft dampers. See revised drawings for more information.

b) The specifications and equipment schedule are included with the engineering design package. Because the new TPO roof systems calls for an R-30, curb adapters will be required. See plans for more information.

c) The only fans are running off existing VFDs are in the EG Building. The fans in Building A do not require VFDs. Refer to the Schneider Electric as-builts for more details and refer to equipment schedule.

d) A core sample will not be performed by the Government. Typically, we perform core samples on roofs where the thickness and composition of the roof system is unknown. The existing roofing system is a mechanically fastened 47-mil Sarnafil single ply roofing system, with two layers of staggered insulation with a R-19 total.

e) The exhaust fans scheduled to be replaced can be handled without a crane. The largest fans are located in the engine generator and the kitchen fryer exhaust, these will require a crane to clear the equipment parapets. The contractor is required to develop a plan for approval and exhaust fan replacement must be coordinated with re-roofing activities.

Item 4 Building A Roof and Exhaust fans questions:

a) Can the PowerPoint presentation that was shared at the site visit be provided?

b) Roof Drawing No. ZHU-D-ARTCC-A210, note #2 states “The contractor shall maintain positive flow towards the roof drains. No standing water will be allowed on any roofing area.” Is the intention of the statement to request a full tapered roof insulation system?

c) Roof Drawing No. ZHU-D-ARTCC-A210, note #6 states “Coordinate replacement of the roof drains with drawings ZHU-D-PSBLD06-G001 thru G003, M100 thru M105, M001, E100 thru E105.” Can you provide those drawings? They were not provided.

d) Roof Drawing No. ZHU-D-ARTCC-A210, note #7 states “Refer to drawings ZHU-D-ARTCC-E072-A and ZHU-D-ARTCC-E073-A.” Can you provide those drawings? They were not provided.

e) Can the existing lightning protection system be “reinstalled” or is the intent to have a “new” system?

f) Can structural as-built drawings be provided for both buildings?

g) Is there slope in the metal deck?

h) Is there a record of the existing roof composition makeup that can be provided? What is the thickness and type of existing roof insulation?

Response:

a) Presentation was for informational purposes and internal use only, it was an aid during the pre-bid. Hard copies of drawings will not be sent. If the Contractor requires full size printed drawings, they will need to contact a commercial printing service.

b) Yes, the intent of the design is to have tapered insulation that redirects water towards the roof drains. This was intended to fix ponding issues on the existing flat roof. Section 07 54 23 3.1A outlines the required slopes for roof installation. Plan view shop drawings for insulation boards in must be submitted for approval including tapered board and/or crickets, etc.

c) Note #6 on drawing A210 contained typos. The drawing numbers have been updated to ZHU- D-ARTCC-G103-105; D021-D026; M074, M117-M119; E106, E118-E119. They are in the package. Contractors prepare their proposals to comply with detail E/A212 for a 6 in.

diameter roof drain. See specifications 22 14 23 Storm Drainage Piping Specialties.

d) These drawings will be distributed to the bidders with RFI responses.

e) The intent is to protect and reinstall the existing system as new roofing construction is completed. The contractor must hire a UL certified installer to re-install all grounding and lightning protection. The contractor must replace any mounting hardware that becomes damaged during re-roofing activities. See Section 26 41 13 and FAA-STD-019F attached.

f) Structural drawings will not be provided. The existing steel deck is 1-1/2 inch, 20 GA Corruform metal deck with 2” light weight concrete from column line FF to W. From column line FF to HH is a standard 1-1/2 inch 20 GA, NO CONCRETE. See drawing ZHU-D-ARTCC-A103 for column line references.

g) The existing roof deck is flat.

h) A core sample will not be performed by the Government. Typically, we perform core samples on roofs where the thickness and composition of the roof system is unknown. The existing roofing system is a mechanically fastened 47-mil Sarnafil single ply roofing system, with two layers of staggered insulation with a R-19 total. Average insulation thickness is 4 to 5 inches.

Item 5 Site visit presentation pictures: I was at the walkthrough on 1/3/22 and we were shown some pictures on a slide, is there any way that you could send those pics to me?

Response: Relevant pictures have been included in the RFI responses.

Item 6 Hazardous Material Spec 070150.19-4 G: Will repairs to the existing areas where hazardous materials are found to be done by the prime contractor? How will payment & methodology be determined?

Response: The EG Building and Building A have been re-roofed to the steel deck. No hazardous materials are expected to be there. Any unforeseen site conditions found will be addressed through the contracting offier.

Item 7 070150.19-8 Prep for Reroofing section E&G: Cannot Locate Steel Deck to be replaced on drawing.

No spec 099113 Exterior painting found.

Response: Re-roofing scope is limited to building-A only, engine generator building WILL NOT be re-roofed. High Performance Coatings, 09 96 00 has been added. The steel deck does not show indications of damage; if differing site conditions are discovered, notify the contracting officer immediately.

Minimum structural requirements for steel deck must be I=0.213 in⁴/ft; S=0252 in³/ft; min. allowable stress of 20 ksi. Deck must resist a diaphragm shear of 300 plf.

Item 8 700150.19-8 3.5 Temp Roofing: Using a hot asphalt temporary roof on an existing Carlisle TPO roof is not advisable or prudent due to melting and moving hot asphalt containers over existing or completed roofing areas.

Response: Disregard the use of hot asphalt as a temporary roof patch. Section 70 01 50.19 has been updated. Use the manufacturer’s recommendations for temporary patches between TPO and PVC.

Item 9 700150.10 D-5: Section 075700 is not found in documents

Response: Section was added, it is intended for temporary overnight or emergency patching and it must only be used if compatible with existing PVC and new TPO.

Item 10 TPO Roofing 075423-11 C-7-C: Calls for minimum R value of R30, does this include tapered & cover boards?

Response: Yes. Insulation is required to ne in two or more layers with staggered joints. Contractors must submit insulation plan for approval.

Item 11 Employee Background Check Requirements: For employees and sub workers what will be required to work outside building on the roof? What will be required if work is needed inside the building such as roof drains and mechanical equipment modifications?

Will workers that have approved badging to work in Harris County and Harris Health Hospitals be acceptable or must they in addition go through owner’s additional background check procedure?

Response: You will be required to have all employees and subcontractors complete the security procedures outlined in Division 1 and contract clauses. All employees and subcontractors planning to work at the site more than 30 days must meet all FAA security requirements and pass the FAA background check. See 01 10 00, 1.10. A.

Item 12 Roof Insulation requirements Clarification and related information:

a) Is R-30 minimum required at drain or is it average required?

b) Is ¼”/ft tapered insulation required in addition to R-30 minimum bade layer?

c) Can the insulation be mechanically attached since the roof membrane is to be welded to fastener plates or should the insulation be fully adhered?

d) Is cover board required over the iso insulation? If so, can it be mechanically attached or must it be fully adhered?

e) Is gypsum board required over the existing metal deck?

f) Is temporary roof required? If so, can it be modified bitumen membrane material?

g) Is the existing deck a metal deck only or is there a lightweight concrete fill over the metal deck?

Response:

a) It is average required. Insulation is tapered at the drain.

b) Tapered insulation is required. ½” slope is required per 20 feet. Insulation slope and layout must be submitted as part of the roofing submittals. Variations will be reviewed depending on the roof location and obstructions. The goal is to minimize water ponding.

c) The TPO basis of design includes a mechanically fastened system with induction welding. In addition, seams will be mechanically fastened with standard heat welding per the manufacturer’s requirements. See 07 54 23 for more information.

d) Densdeck type boards are required at the deck and top of the insulation. Densdek type board at the deck must be fire resistant. The entire system is mechanically attached through the deck.

See 07 54 23 for more information.

e) See d) above.

f) Temporary roofing patch will be required at the end of the day or in case of rain. Modified bitumen is not compatible with TPO or single ply PVC membrane. All temporary patching materials must be compatible with PVC and TPO.

g) The existing steel deck is 1-1/2 inch, 20 GA Corruform metal deck with 2” light weight concrete from column line FF to W. From column line FF to HH is a standard 1-1/2 inch 20 GA, NO CONCRETE. See drawing ZHU-D-ARTCC-A103 for column line references.

Item 13 Alternate Roof System: Install a certainteed or equal SBS Modified Bitumen self-adhered system

Response: The TPO basis of design includes a mechanically fastened system with induction welding. In addition, seams will be mechanically fastened with standard heat welding per the manufacturer’s requirements. See 07 54 23 for more information. Modified bitumen does not meet basis of design.

Item 14 TPO Roofing 1.9 Quality Assurance: Can we utilize material Manufacturer’s system inspector for our area?

Response: Yes, that is part of the process to have the roof warranty certified. See 07 54 23 for more information regarding SH Special Warranty.

Item 15 Site visit questions:

a) Please provide a copy of the sign in sheet from the site visit. Will a second site visit be allowed?

b) Please provide the photographs that were on the slide show at the site visit.

c) It was mentioned at the site visit that exhaust fan 10 was going to be removed from this project.

Please confirm and if so will an amendment be forthcoming?

d) Will you please identify on the mechanical plans, the exhaust fan designation numbers?

(specifically building A)

e) The scope of work includes only the replacement of the exhaust fans. Intake hoods and exhaust hoods, as well as kitchen hoods are identified in either the plans or specifications but not the description of work. Please confirm the fans only are to be replaced.

f) The specifications indicate frequency drives are required. Where are the drives to be located?

g) To what extent are ducts to be replaced? We assume as necessary for the installation of the new equipment?

h) Are new roof curbs required or can the existing curbs be re-used?

i) Are the removed exhaust fans to be turned over to the FAA?

j) The specifications indicate existing ducts are to be cleaned. Will you provide mechanical drawings identifying the existing duct systems?

k) Is there a sequence of equipment to be removed? Can all equipment be removed at (1) time?

l) The equipment schedules have a few items which may not be available, or seem a little peculiar:

a. 30,000 CFM fans with direct drive

b. 300 CFM fan with 3 H.P motor

c. 30 CFM roof mounted fan, with 2,675 RPM motor

d. Propeller fans, roof mounted, to replace dome-type fans?

m) The drawings indicate a kitchen vent hood to be replaced. Is there a schedule to identify them?

n) Stainless steel hoods are identified to be replaced (drawing M117). Are there schedules or specifications for the hoods?

Response:

a) The site visit sign in sheet will not be made available to the public. A second site visit will not be scheduled.

b) Presentation was for internal use and help explain the scope of work. Selective pictures are included with the RFI responses. See attachments.

c) Exhaust Fan 10 has been removed from the scope of work from the project. Delete Exhaust Fan 10 from ZHU-D-ARTCC-M119. See revised attachments.

d) Drawings have been updated. See attachments.

e) Drawings have been updated. See attachments.

f) Building A do not have VFDs. The VFDs are located in the EG Building. Refer to the Schneider As-built drawings for more details.

g) There will be some new ductwork at the roofline interface. Ductwork is limited to the connection of exhaust fans to the roof curb for proper fit.

h) New roof curbs are required in Building A. The new roof curbs must be a minimum of 8” above the roof membrane. Roof curb height at 12” are included in the specifications to compensate for the thickness of an R-30 roof, but that may have to be adjusted to meet the 8” threshold. Curbs at the Engine Generator Building can be reused since there is no re-roofing. Curb adapters/extenders will be considered with prior approval.

i) No. Please make sure that they are disposed properly.

j) The only cleaning is required at the connection of the exhaust fans to the roof curb as the exhaust fans are fitted to the new curbs.

k) The contractor shall submit their sequencing plan as a submittal for approval. Please be aware that Building-A exhaust fan replacement will have to coordinated between mechanical and roofing trades because re-roofing operations will impact curb height.

l) Mechanical drawing ZHU-D-ARTCC-M119-A contains corrections and clarifications. See attachments.

m) Mechanical drawing ZHU-D-ARTCC-M119-A contains corrections and clarifications. See attachments.

n) Section 23 34 23 Part B of the specifications. Drawing ZHU-D-ARTCC-M117-A was revised. See attachments.

Item 16 FAA Roof/Exhaust Fan Question:

a) Has there been a core sample completed on the roof?

a. We can provide the proposal with what we would recommend being replaced with as far as ISO board, insulation, nails, etc.

b) The exhaust fan regarding the EQ building, I overheard that the exhaust fans are to be done individually.

a. The reason this is necessary knowledge is that we may have to pack in/out a crane, and this could get very costly, and I don’t want to over or under budget this expense.

Response:

a) A core sample will not be performed by the Government. Typically, we perform core samples on roofs where the thickness and composition of the roof system is unknown. The existing roofing system is a mechanically fastened 47-mil Sarnafil single ply roofing system, with two layers of staggered insulation with a R-19 total. Average insulation thickness is 4 to 5 inches.

a. The TPO basis of design includes a mechanically fastened system with induction welding.

In addition, seams will be mechanically fastened with standard heat welding per the manufacturer’s requirements. See 07 54 23 for more information. Only TPO systems will be considered.

b) The contractor shall submit their sequencing plan as a submittal for approval. Exhaust fans in room 501 shall be replaced first. Once completed, the Contractor may proceed to room 503. This will be part of the overall construction plan because of the engine generators. Generators are critical to the operation of the facility.

a. The exhaust fans scheduled to be replaced can be handled without a crane. The largest fans are located in the engine generator and the kitchen fryer exhaust, these will require a crane to clear the equipment parapets. The contractor is required to develop a plan for approval and exhaust fan replacement must be coordinated with re-roofing activities. A crane will be required to load up materials to the roof.

Item 17 Site visit presentation and full size drawings:

I am submitting this RFI regarding the controls portion of the exhaust fans on this project. The kitchen hood specification refers us to two separate control spec sections that are not part of our bid package.

Please also provide the point of contact for the existing DDC system who we may reach out to for help pricing the project.

Response: Modified specifications are attached.

Item 18: RFI Questions

a) Please confirm that all fans do NOT need to be stainless steel exterior/housing construction.

b) Is the fan noted on M117 as “kitchen vent hood” is an intake fan, or exhaust as scheduled.

c) Are new VFDs/starters required? If so, are they located indoors or on the roof?

d) Are belt drive fans acceptable?

e) What are the CFM and TSP requirements for Fans EG Garage, AEX1, and AEX2?

f) Could you confirm that seismic specification requirements are not applicable?

g) Could you confirm the minimum curb height?

h) Should the dampers on fans be gravity backdraft style (not motorized, or requiring separate power and control)?

Response:

a) Yes, aluminum exterior hoods are an acceptable alternative. See new attachments.

b) The fans are direct drive. The kitchen hood is an exhaust fan.

c) The fans are direct drive. No new VFDs are required.

d) The replacement of the exhaust fans must match the performance requirements of the specifications.

e) The performance are outlined on ZHU-D-ARTCC-M119-A.

f) Exhaust Fans must meet the wind criteria for inland coastal areas. There are no seismic requirements for this area. See modified specifications.

g) The minimum curb height is 8 inches above the finished roof surface. The actual roof curb height may be more than 8 inches. Curbs at the Engine Generator Building can be reused.

h) Yes, that is acceptable, with the exception of the exhaust fans in the Engine Generator

Building. Field verify the location and function of the exhaust fan.

End of Document