Amendment 1.pdf

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1. Can Elevation drawings of the penthouse and the lower attached roof section be provided to determine the type of crane needed to load materials?

Yes. See attachment “OSW Elevations.”

2. Drawings A003 Detail A/D001 and 1/A003 indicate existing lightweight concrete over a metal deck. Is this correct and is it throughout the penthouse and lower attached roof sections?

Penthouse roof has only metal decking. Lower OSW main roof is lightweight concrete over metal decking. See attached As-Built drawings, for reference only.

3. Does the new roof installation require a RoffNav number or does it just need to meet FM Global wind uplift requirements?

New roof does not require a RoofNav number, but all new components and materials installed must be listed in FM Global’s RoofNav Class 1 database. See Specification 075423 – Section 2.2 for specific parameters.

4. Detail A-D001 shows plywood on the interior side of the tall walls (main roof level). Is this new or existing?

Plywood exists on all OSW main roof level parapet walls. By visual inspection, these walls all appear to be weather damaged. Assume all interior side parapet plywood walls are damaged and must be replaced. In addition, parapet details must now include wood blocking that follows contour of parapet cap flashing, to mitigate damage from anchors that window washers routinely use. See amendment to detail 1/A003. Modifications to be made as necessary by roofing manufacturer.

5. If the lower roof is lightweight concrete, how do we attach the substrate board and the membrane?

The roof will still need to be mechanically attached to the lightweight concrete decking to avoid possible odor penetration into penthouse air intakes. Attachment methods and fasteners to be approved by TPO roofing manufacturer to meet 20-year warranty requirements.

6. If the lower roof is concrete, do we still need to install the substrate board?

The substrate board can be omitted, as allowed by IBC-2015 2603.4.1.1. The concrete deck takes the place of the thermal barrier for the insulation. Only the protection board is needed. See revised OSW Main roof level detail.

Additionally, penthouse roofing will remain the same. See Penthouse Roof Only detail:

7. What type of decks are the Alternate Annex roofs constructed of?

There are no As-builts documenting the composition of the annex roofs. Assume there is a combination of metal stud and 2”x4” wood framing.

8. On Drawing Sheet E002, it mentions in note #4. “see Architectural drawing A039 Detail #4 for Ground Guard Support, Paint Ground Guard to Match Insulated Panel.” ”.

Can we get Sheet A039?

Yes, See attached. In addition, the referenced detail 4/A039 shows the existing down connections on building wall panels. New lightning protection work is required up to these down connections, where the new system will tie into. Thru-wall lightning protection penetrations must be redone to route around parapets and connect to the existing down connections.

9. SPECIFICATIONS CALL FOR UL CERT: The certification will be in the form of Letter of Findings by UL for roof top only. Letter of findings is typically used in a roof top situation where it may not be possible to verify the existing grounding system.

A letter of findings is acceptable.

10. NEW FIBERGLASS HAND RAIL SYTEM ON PENTHOUSE ROOF LEVEL.

Must have lightning protection system installed on hand rail to comply with Lightning Protection Standards unless the AHJ will require no protection on the handrails.

The fiberglass rails do not need to be grounded since they are non-metal. We require only EPDM pads (from same rail manufacturer) underneath each modular base to protect roofing membrane from damage.

11. USE OF MANLIFT: Will the use of a man lift be required to access the roof for all personnel at all times.

Construction access will be limited to approved access routes in the OSW building. The stairwell is available for construction personnel to access the OSW roof and penthouse roof. The stairs cannot be used for removal of demolition material or construction equipment.

12. WORK HOURS: Will the contractors be able to work on weekends and extended hours during the week?

Weekends and extended hours are permitted, but require advanced approval by the

COR.