RFI ANSWERS 9 SEP 21.pdf

RFI Answers - W50S6Q21B0006 RANGER TOWER REPAIRS - 9 September 2021:

1) Clarifying that wood blocking can be installed at the perimeter to match the thickness of the tapered insulation and to facilitate edge metal installation

Per SECTION 07 01 50.19, PREPARATION FOR RE-ROOFING, Para. 3.6 “Install pressure-preservative treated exterior plywood sheathing . . . “. This requirement would also apply to any necessary wood blocking.

2) Clarifying the starting thickness of tapered isocyanurate insulation at the perimeter and amount of slope per foot slope for the tapered isocyanurate. (Is 1.5" starting thickness acceptable and 1/4" per foot slope tapered isocyanurate insulation acceptable?)

Per SECTION 07 54 23, THERMOPLASTIC POLYOLEFIN (TPO) ROOFING, Para. 3.4 INSTALLATION –

GENERAL:

“Install products according to manufacturer's instructions and approved submittal drawings.”

If the requested starting thickness and slope are in accordance with the manufacturer's instructions, we would have no objections. It is not our intention to deviate materially from the specifications of the entity responsible for warranting the work.

3) Is 1/4" gypsum cover board over the tapered isocyanurate insulation to provide compressive support below the roof membrane acceptable?

Per SECTION 07 01 50.19, PREPARATION FOR RE-ROOFING, Para. 1.3, ASTM C1177/C1177M-17 allows Glass Mat Gypsum Substrate for Use as Sheathing. Gypsum cover board is acceptable as long as it complies with the referenced publication.

4) Is an alternate roof system with a two ply modified bitumen membrane system that incorporates a liquid applied flashing system for the guard rail stanchions acceptable?

A Thermoplastic Polyolefin (TPO) roofing system was recommended by the Air National Guard Readiness Center for this application. We are not considering alternate systems.