1. Article Body
Cold storage reroof costs more per square foot than almost any other single storey commercial building, and the roofing is not where most of the difference sits.
Costs vary by market and building, so this explains the structure rather than quoting figures.
The assembly itself
Insulation thickness. Far greater than an ordinary commercial roof because the temperature differential is large and refrigeration energy is the dominant operating cost. This is a large material quantity.
Vapor retarder. A continuous, properly detailed vapor retarder on the warm side, with every lap and every penetration sealed. Material cost is modest, labor and detailing cost is not.
Thermal break detailing at fasteners and terminations.
Taller curbs and reworked terminations to suit the thicker assembly.
The wet assembly question
If the existing insulation is saturated and frozen, it cannot be covered. It comes off.
Removing frozen saturated insulation is slower and heavier than removing dry material, and disposal is priced by weight.
This is the single largest unknown in a cold storage reroof and the reason a moisture survey before pricing is worth more here than on any other building type.
The operational constraint
A freezer cannot simply be opened.
Either the product moves, which means third party cold storage, transport and handling, or the space is temporarily shut down and warmed, which means loss.
That cost frequently exceeds the roofing cost and it belongs in the project budget rather than being treated as an operational inconvenience.
Phasing has to be designed around which chambers can be emptied, in what order, and for how long. That is a supply chain question.
Temporary conditions
Every night the roof is left open, the vapor barrier is discontinuous and the chamber below is exposed. Temporary terminations on this building type are more demanding than on an ordinary roof, and there are more of them because the phases are smaller.
Weather windows are tighter for the same reason.
Food safety
Work above a food storage chamber brings hygiene requirements, possible third party audit involvement, and protection of product below. Expect the quality team to have a view on the program.
Comparing bids
Require a common written scope covering insulation type and thickness, vapor retarder specification and detailing, thermal break provisions, an allowance for saturated insulation removal with a unit rate, penetration treatment, curb and termination rework, phasing tied to chamber availability, temporary condition standards and food safety protection.
A bid well below the others is usually assuming the existing insulation is dry and reusable. Establish whether it is before you believe any number.
