Soprema is the name a spec writer reaches for when the roof needs layers. The maker is known for modified bitumen sheets and for liquid-applied membranes that cure in place, and both families do their best work where a single-ply sheet struggles: tight details, heavy traffic and roofs that must stay watertight through a long winter. In Coeur d'Alene, ID roofs design for 60 psf of snow, and the real snow climbs east, with Wallace averaging about 75.6 inches a year and Mullan about 112.
We price the layered system, the liquid details and the snow additions on separate lines, so the owner sees where the money goes.
What the Maker Sells: Sheets, Liquids and Boards
The first family is modified bitumen, usually SBS, laid in two plies with a granule-surfaced cap. It is the same layered approach we use on every modified bitumen install. The second is liquid-applied membranes: a resin that is rolled or sprayed over a prepared surface and cures into a continuous layer, good at pipe clusters, curbs and odd corners. The third is insulation board and accessories that go with them.
Each is installed to the maker's published details. A spec may name one family or a combination, such as a mod bit field with liquid-applied flashings. We read it for the combination and for the warranty tier, then price each part.
Insulation and cover board sit under the sheets. A rigid board with a cover board gives the base ply a flat, stable bed and guards against hail and foot traffic. The board shows up as a line with thickness set by the energy code, and we price a heavier cover board where the roof is walked. The board decision belongs in the first conversation, since it changes both the weight on the deck and the height of every flashing.
What It Costs: Plies, Liquids and Labor
Layered roofs are labor-heavy. A two-ply sheet system costs more to install than a rolled single-ply, because each ply is laid, lapped and sealed in sequence. Liquid-applied details cost by the detail: a pipe cluster, a curb, a drain, each priced by count and by the thickness the maker requires. Tear-off, board and edge metal complete the list.
Install method changes the bid. Torch application is the fastest and needs a hot-work plan and a fire watch. Cold-applied and self-adhered sheets avoid the flame and take longer, with more sensitivity to temperature. We show the cost step between methods and note which the building and its insurer will accept. A recover over a dry, sound roof can save the tear-off line.
Access and fire control are lines, not afterthoughts. A torch job needs extinguishers, a fire watch that outlasts the last flame and a post-work check. Cold-applied jobs need warm storage for adhesive. Self-adhered jobs need warm rolls and a deck above the minimum temperature. Each adds a few hours a day, and we price them so the schedule and the budget agree.
Snow Load and Wind: What the City Sheet Adds
A layered, bonded roof handles the city's 115 mph design wind well when it is properly adhered. Snow means a deck and board assembly that will not crush, and drains that stay open through the thaw. Ice barrier goes at the eaves and low-slope edges, where meltwater refreezes and backs up.
Saturated snow runs near 20 pounds per cubic foot, and heavy wet snow on a layered roof is a real load, and the engineer checks it, particularly on older buildings. We locate drains before pricing, add capacity at drift pockets and fasten edge metal to the wind number.
Granule loss and ice are the winter watch items on a cap sheet. Granules wash into drains and scuppers, and a plugged drain under ice holds a pond on the roof. We clear sumps in the fall and after the thaw, and we note any bare patches in the record so a recoat or a repair can be scheduled before the asphalt is exposed to the sun.
East Along I-90: Silver Valley Roofs
The Silver Valley runs about 40 miles east along I-90 from Pinehurst to Mullan, with Lookout Pass at 4,725 feet on the Montana line. Kellogg averages 52.4 inches of snow a year, mostly November through March. Wallace's record season was 1968 to 1969, with 167 inches. Hecla Mining, the largest silver miner in the United States, is headquartered in Coeur d'Alene and runs the Lucky Friday mine in the valley.
Industrial buildings in a mining economy are worked hard, and a redundant roof earns its keep. Near Cataldo, where I-90 runs along the Coeur d'Alene River, and east into the Silver Valley, the snow load argues for a tough, layered roof or a metal roof with real slope. We price the layered option beside a standing seam alternate when the building has the pitch.
Access is a cost in the mountains. A roof at the east end of the valley may sit behind a narrow road or a steep lot, and winter makes both worse. We plan material delivery and hoisting before the bid, and we note any day the road can close a job.
Liquid-Applied Details: Where They Beat a Boot
A prefabricated boot fits a standard pipe. A liquid-applied flashing fits anything. Clustered penetrations, irregular curbs, drains with odd flanges and old repairs with layers of mastic all take a resin that is brushed or rolled around the shape and cures into one piece. The prep matters: the surface has to be clean, dry and primed, and the resin goes on at the thickness the maker requires, with fabric reinforcement at corners.
We use liquid flashing to detail around old built-up roofs, around skylight curbs and around mechanical clusters on rooftop equipment curbs. It adds cure time to the schedule, so the weather window matters.
Schedule and Closeout
Sheet systems and liquids both need dry days above the maker's minimum temperature. We aim for late spring through early fall, stage rolls and resin warm, and close every section by dark. At closeout we walk the roof with the GC, photograph every detail, log thickness readings for liquids and submit the warranty application with the as-builts. Our preventive maintenance visits then keep the file current.
Hold points keep a layered roof checkable. The base ply is inspected before the cap goes on, the laps are checked before the granules are embedded and the liquid thickness is read before the crew moves. Each check takes minutes and each prevents a day of rework in the cold.
The comparison set matters on a layered roof. Owners pricing this maker often want a second view from GAF, which also sells modified bitumen and built-up components, or from Duro-Last, whose prefabricated PVC takes a different route to the same watertight roof. We put each on the same plans with the same lines, so the gap is visible and the choice rests on the roof.
Commercial Roofing Questions
Is Soprema only modified bitumen?
No. The maker also sells liquid-applied membranes, insulation and other low-slope products. We read the spec for the family.
Do you torch it down?
Only where the building and the insurer allow it, with a fire watch. Cold-applied and self-adhered options exist.
Why use liquid on a curb?
It forms around the shape with no seams. It fits odd details a prefabricated piece cannot.
Can liquid go over an old roof?
Often, if the surface is clean, dry and sound. We test adhesion on a patch first.
Does it cost more than single-ply?
Usually, on labor. It buys redundancy. We show both prices.