Duro-Last sells a roof that arrives mostly built. The maker fabricates PVC membrane panels to the measurements of your roof, with the boots, corners and curb flashings already formed, and the crew welds the panels together on site. That moves labor from the roof to a factory and shortens the time the building sits open. It also moves risk to the measurement day, because a panel cut to the wrong dimension is a week lost. In Coeur d'Alene, ID the 60 psf design snow applies to a prefabricated roof the same as any other.
We price the measurement, the panels and the snow additions on separate lines.
How It Works: Measure, Fabricate, Install
The sequence is fixed. We measure the roof and the penetrations. The maker fabricates panels, boots and flashings to those dimensions. The panels arrive rolled and labeled, and the crew lays them out and welds the field seams with hot air. Most of the heat-welding that would otherwise happen on the roof was done in the plant, so the field seams are fewer and the detail work is mostly bolt-on.
The membrane is PVC, with its resistance to grease and chemicals, and it can be installed over an existing roof when that roof is dry. Over a tear-off, the system goes down on new insulation and cover board. A recover is possible where the structure allows it.
Insulation and cover board are still field items. The board goes down first, then the panels. We show thickness set by the energy code and an upgrade for roofs with traffic or hail exposure. Edge metal is formed on site or ordered with the package, and it is fastened to the wind number on the city sheet. The detail is simple and it is where a prefabricated roof is most often shortchanged, so we price it separately.
What It Costs: Where Prefabrication Saves and Where It Does Not
Prefabrication saves field labor and speeds the install. On a roof with many penetrations, the formed boots and curb flashings save the most. On a plain rectangular roof with few details, the saving shrinks, and a standard welded sheet may price lower. The cost lines are the panel package, insulation and cover board, edge metal, drains and tear-off.
The risk line is measurement. A roof that is measured wrong produces panels that do not fit. We take dimensions twice, verify penetration locations and confirm the finished substrate before the order is released. Lead time matters too. Fabrication takes time, and a late order can push a job into the snow. We flag the date the order must go in.
Warranty terms come from the maker and depend on the system, the thickness and the installation. We read the current terms and list them with the cost of each tier. A fuller term typically asks for tighter installation and sometimes more attachment. The owner should see the step before choosing it.
Where It Fits: Small and Mid-Size Roofs with Many Details
The system suits restaurants, retail strips, small offices and clinics, where roofs have a lot of penetrations for their size and the building stays open. In Rathdrum, Hayden or Dalton Gardens, a small commercial roof with many penetrations is the case we look at for prefabricated PVC. Rathdrum is a fast-growing prairie city, and in Dalton Gardens roof work leans residential and small commercial, so modest roof sizes are the expectation.
On very large flat roofs, a field-rolled sheet usually prices better. We show both when the roof sits on the border. Sika Sarnafil is another PVC-led name that often gets priced beside this one on the same plans.
Snow, Wind and Ice: What We Add
A prefabricated roof still answers to the city's severe weathering rating, and it still needs drift-pocket drains, edge metal fastened to the wind number and ice barrier at the eaves and low-slope edges. Snow runs heavier toward the east end of the Silver Valley.
Welds are tested the same way as any PVC roof. A test weld is made at the start of each shift, cut and pulled. Field seams are probed after cooling. In cold weather the sheet is stiffer and slower to weld, and we adjust or wait. A prefabricated roof is faster, not less demanding.
Drainage gets the same attention it gets on any roof. Prefabricated panels do not change where water goes, and a sump set high still holds a pond. We confirm drain locations and slopes before the measurement is final and add a drain or a cricket if a drift pocket will form behind a unit.
Staying Open: Why Speed Matters to a Tenant
A restaurant, a clinic or a small retail store cannot close for a week. A prefabricated install shortens the exposed time, because most of the details arrive formed. The tear-off or prep happens in sections, the panels go down behind it and each section closes by dark. Noise and odor are scheduled with the manager, and intakes are shielded. Our occupied building reroofing plan lists those lines apart from the membrane price.
Fire safety matters on a kitchen roof. We keep hot work away from grease and confirm the assembly's fire rating against the plans before we order, since the rating belongs to the whole assembly and not to the sheet alone.
Keep the tenant informed. A one-page schedule with dates, hours and what to expect goes to the manager before the first day, and we attend a tenant meeting if asked.
Repair and Schedule: Existing Roofs and the Weather Window
Many calls are about an existing prefabricated roof, not a new one. The failure points are the field seams between panels, the termination at walls and the penetrations added after the install. We probe the seams, check the terminations and look at every added pipe or unit. Repairs use compatible PVC, hot-air welded, and are logged in the warranty file with a date and a photograph. Where the terms limit who may repair, we say so and help the owner notify the right party. Roofs that need more than patching are compared with Soprema layered systems and a field-rolled sheet, on the same plans.
Installation follows the single-ply window, from spring thaw to the first heavy snow. The panel order is released after measurement, and delivery is confirmed in writing before the start. A late panel is the usual delay, so the date goes in the bid. Winter calls get a temporary closure and a permanent fix when the weather allows.
Every section closes by dark. If the forecast turns, the open section is covered and the work stops. That rule costs a few hours and protects the interior, which is the point of choosing a fast system in the first place.
Closeout and Maintenance
At closeout we walk the roof with the GC, probe the seams, photograph the formed details and submit the warranty application with the as-builts. The maker's file asks for dates, photographs and measurements, and we keep them together. A restaurant roof needs a grease cleaning plan, and our preventive maintenance visits carry it out and add the dated record.
Commercial Roofing Questions
Does prefabrication cost more?
It can, on a plain roof. On a roof with many details it often saves labor. We price both.
What if the measurements are wrong?
Panels are fabricated to the numbers, so we measure twice and verify before releasing the order.
Can it go over an old roof?
Yes, if the old roof is dry and sound. We scan and core first.
How long does fabrication take?
It varies with the maker's schedule. We confirm the date before the start is set.
Is it good for a restaurant?
PVC resists grease, so it is a common pick. We detail the exhaust and add a cleaning plan.