Pre-Bid Site Inspection Questions and Answers Bldg 2316.docx

Pre-Bid Site Visit Questions Site visit: Nov 4, 2019 Response Date: Nov 19, 2019 Solicitation No: FA489720B0001 Project: Repair Roof Bldg 2316

Question 1: There are 2 large HVAC units that will come close to not making the required height of 8 inches for the roof flashing. These will require a large crane to raise and build up the 8 inch height required. The roofing manufacturer will ok for warranty the curb flashing at a minimum of 6 inches. The 2 HVAC units are #2 and #3 as shown on the drawing that I am attaching. As they are, they would be around 7 inches of height with the new ¼” taper slope.

Would that be acceptable?

Answer 1: The top of the curb for HVAC equipment needs to be ~ 8” above the elevation of the PVC membrane (the finished roof deck). If the final height is ~ 7”, it needs to be within the mfg. recommendations and not void the 20 year mfg warranty.

Question 2: On sheet A-001 of the plans Key Note 1 it is stating that there is 1 layer of ½” high density protection board over R-30. In the specifications section 07 22 00 Roof and Deck Insulation 2.4 Cover Board it states to provide and install two layers of ½” cover board as a high density cover board. The roofing manufacturer representative is questioning this and says 1 layer is normal. Will one layer of 1/2'” high density cover board be sufficient or should we install 2 layers?

Answer 2: Qty one (1) layer of 1/2'” high density cover board will be sufficient.

Question 3: About specification. Part 2 products. 2.1.5 Membrane Flashing Provide membrane flashing, including self-adhering membrane flashing, perimeter flashing, flashing around roof penetrations and prefabricated pipe seals, of a minimum polymer 90 mil thickness reinforced PVC for 20 year warranty, and utilized as recommended and supplied by the roof membrane manufacturer Submit certification from PVC membrane manufacturer that the proposed PVC membrane roofing product meets the polymer thickness specified.

None of the Manufacturers listed meet this requirement.

Answer 3: “Minimum polymer 90 mil thickness reinforces PVC for 20 years” should read, “Minimum polymer 80 mil thickness reinforces PVC for 20 years”

Question 4: Roofing products manufacturer approval.

I am asking if I could get GAF approved for the PVC membrane for Repair Roof Bldg 2316 FA489720B0001 (See EverGuard Attachment).

Answer 4: GAF PVC 80 mil smooth membrane will be approved if, material submittals from GAF meet the required design strength criteria as called out in the Design and Specs. GAF Technical services will provide Wind Load calculations to Select / Master GAF Contractors (Call GAF Tech Support at: 951-360-4200 Western Sales Office)

Question 5: At the site visit we were shown one of the large abandoned curbs that is to be removed and the roof decking replaced or repaired. The 2 large curbs seem to be made of 1/8” or greater steel that has been welded to the existing steel roof truss and the steel roof decking was welded to the base of the steel curb.

To be able to remove those 2 curbs we would need to remove a large portion of the existing roof deck and cut out the steel curbs. This would require the use of grinders and possibly a cutting torch. Also we would have to close of a large area under those units for safety purposes. This would a lengthy part of the project to complete.

I propose that we leave the curbs in place and sheet over and insulate them and the install the PVC roof over them. The small curbs would not be a problem to remove and repair the decking.

Answer 5: The desire end state is a properly sloped and continuous sealed roof surface. Enough of the curbing material needs to be removed to achieve the specified roof design.

Question 6: When we were inspecting the curbs from underneath I noticed that the existing electrical conduits were installed by attaching them to the underside of the steel roof decking.

That makes it impossible for us to mechanically fasten the insulation to the steel decking without the possibility of penetrating through the conduit and causing an electrical short.

We can fully adhere the insulation to the steel roof decking but there is one problem. To achieve the Structural Design Criteria that you are wanting we would have to attach the insulation directly to the steel decking without a vapor barrier to be able to get the extra wind warranty from the roofing manufacturer.

There is NO FM wind design for adhering insulation to a steel deck.

Would that be acceptable to you?

Answer 6: Installing roof insulation without a vapor barrier is acceptable.

Question 7: Will we be able to have the parking lot located at the North West corner of the building to set up for the demolition of the roof? There seems to be only 1 access point at that corner to get our demolition and materials on and off the roof.

Answer 7: See attached map for dumpster location.

Question 8: Where will we be able to stock are materials for the project?

Answer 8: See attached map for material yard location.