Johns Manville sells the membrane and the insulation under it, and a spec that names JM often names both. That is good for the warranty and tricky for the bid, because the insulation board is the heaviest cost line after labor. The 60 psf design snow and the energy code Idaho enforces statewide, which sets a minimum insulation value, both push the board thicker.
We price the board first, then the membrane, then the snow-country additions, each on its own line.
The Range: Membranes and Boards Under One Name
On the membrane side, JM's commercial line covers single-ply families such as TPO, PVC and EPDM, along with modified bitumen and built-up components for layered roofs. On the insulation side, it supplies rigid polyiso board and cover board used under many makers' membranes. A spec might name the full JM system or only the board, and we read it to see.
When the board is named and the membrane is open, we price the membrane alternatives against the board's requirements. TPO is the common pick for large flat roofs, and PVC is the pick where grease or chemicals reach the roof. Layered roofs, with modified bitumen, suit buildings that want redundancy.
Fasteners, plates and adhesives complete the set. A maker's warranty often names the accessories it will accept, and a substitute can void it. We carry the approved list in the submittal and flag any change before the order, so the GC is not surprised by a rejected pallet at the gate.
Insulation Cost: Thickness, Layers and Cover Board
Board thickness sets a large share of the bid. A thicker assembly costs more in material, and when it is installed in two staggered layers it costs more in labor, but it saves heat and keeps seams from lining up. The code minimum sets the floor. Tapered board, which builds slope toward drains, adds a line for the taper plan.
Cover board goes over the insulation and under the membrane. It protects the board from hail and foot traffic, spreads loads and gives the membrane a firmer bed. We show cover board as an alternate on roofs with traffic or hail exposure, and as base scope where the maker's warranty calls for it. Our insulation and cover board scope lays out the choices with prices.
Moisture control belongs here too. Board stored on the ground absorbs water, and wet board under a new membrane is a failure waiting for the first thaw. We stage board on pallets under cover, install only what we can close in the same day and reject any sheet that arrives damp. A hold point at the deck checks it for moisture before the first board goes down.
Snow and Wind: What the City Sheet Adds
For an insulated, membrane-covered roof, the snow load asks for a deck and board assembly that will not crush, and the wind number asks for fasteners and plates sized to the corner and perimeter zones. We show the fastener pattern in the submittal so the permit reviewer can check it.
Wet snow is the heavy case. Saturated snow runs near 20 pounds per cubic foot, so a roof that looks lightly covered can carry a lot. Drift pockets behind parapets and units stack that load further. We locate drains and scuppers before we price and add drain capacity where a pocket will form, and on a roof with a deep stack of board we recheck the parapet and curb heights, since each added inch of insulation raises every flashing that sits on the deck.
Where It Gets Specified: Clinics, Hospitals and Plants
Healthcare buildings combine tight schedules with heavy mechanical loads. Kootenai Health is the largest employer in Kootenai County, and in Post Falls Pleasant View Surgery Center and the Rehabilitation Hospital of the Northwest are among the larger employers, so roofs over patient space are a regular question here.
Manufacturing is the other group. Buck Knives, headquartered in Post Falls since 2005, and Tedder Industries are among the larger employers there, and plants bring exhaust and equipment loads that shape the membrane choice. For any of them, we read the spec against the building's use before we price.
Working Over Occupied Space
A clinic or plant keeps running during a reroof, and the phasing is a cost. Each section is torn off, insulated and closed in a day, with protection inside and out, quiet hours respected and intakes shielded. Hospitals set their own rules for noise and air quality, and we follow them. Our occupied building reroofing plan lists the phasing lines separately so the owner sees what staying open costs.
Hold points keep the work checkable. The deck is checked for moisture before the board goes down, and each section is inspected before the next one opens.
Schedule and Lead Time: Board First, Membrane Second
Insulation board and membrane ship from different plants, and either one can be late. A flat-roof job needs both on site before the tear-off opens, or the crew sits idle with an open roof. Both delivery dates get confirmed in writing, stage material on the roof or in a protected laydown, and start only when the dry-in material is in hand. A late board in September can push a job into the first snow, and we flag that risk in the bid.
The same discipline applies to tilt-up and flex buildings at Riverbend Commerce Park, where roofs close in a short window, and to light industrial work in Hayden. Tear-off and dry-in happen on the same day. A section is not opened unless we can close it by dark.
Existing roofs that carry a JM warranty get a different first step. We read the terms, document the condition and contact the right party before any repair, because an unapproved repair can end the coverage. Where the terms allow, we repair with compatible materials and log every fix with a date and a photograph, so the file shows the maker what was done, when and by whom.
Closeout: Warranty File and Maintenance
The warranty application, the as-builts, the photographs and the board and membrane lot records all go in the file. A maker's warranty reviewer asks for them. After completion, a fall walk and a spring walk keep the roof inside the maintenance terms, and our preventive maintenance visits produce the dated record. The comparison with Holcim Elevate or GAF systems on the same plans comes down to the warranty tier and the board.
Hold the final payment application until the punch list is closed and the warranty paperwork is in. That is the GC's hold on a job, and it protects the owner too.
Commercial Roofing Questions
Does a JM spec mean JM insulation too?
Often. We read the spec for the membrane and the board separately and price what is written.
How thick should the board be?
As thick as the energy code and the spec require, plus any extra the owner wants. We show the code minimum and the step above it.
Can we mix makers' boards and membranes?
Sometimes, but the warranty may need one maker's full system. We check before the order.
What if the roof has wet insulation?
It comes out. We scan and core first, carry a unit price for wet board and cut out only what is wet.
Do you work with hospital infection control rules?
We follow the facility's rules for noise, dust and air. We plan the work with the facility manager before the first day.