A warehouse roof bid is mostly a snow bid. In Coeur d'Alene, ID the design snow load is 60 psf, and on a wide, mostly open roof the money sits in the few places where that load stacks up: behind a parapet, along the low side of a step, beside a dock canopy. The field of the membrane is the cheap part of the job. We price the field once and price each pocket by itself.
Owners and general contractors comparing two warehouse numbers should line up three items before they look at either total: tear-off or recover, how many drains and scuppers each bid carries, and what edge metal is specified. Those three lines explain nearly every gap between bids. Send us the plans and we show all three apart from the field price, so the difference has a name.
What the Code Sheet Says: Load, Wind and Frost
The City of Coeur d'Alene sheet of adopted design criteria is the document a warehouse roof submittal gets checked against. Alongside the 60 psf snow load it names a 115 mph wind design, Seismic Design Category C and a 24 inch frost line, and it calls local weathering severe. For a warehouse that reads as a short list of line items, not a lecture.
Snow load decides whether the existing deck and framing can take a heavier assembly, and that decides whether a recover is even on the table. Wind speed decides the fastening pattern at the perimeter and corners, where uplift is highest. The frost line matters less overhead, but it governs how the dock aprons and downspout discharge behave below the roof edge in January. We read the sheet before we open the plans.
What It Costs: Three Lines That Move the Number
Tear-off is the first swing. Pulling a failed membrane and wet insulation down to the deck costs labor, disposal and a longer open window, but it is the only way to find out what the deck has been absorbing. A recover over dry, sound insulation skips that cost and keeps the interior working. If a moisture survey finds wet insulation in only part of the roof, the bid can split: tear off the wet zones, recover the rest.
The second swing is drainage. A warehouse with two interior drains and a long run of scuppers behaves differently from one with a dozen drains. Added or re-sloped drains are a line item. So is tapered insulation to move water off a flat spot.
The third swing is edge metal. Perimeter coping and drip edge take the wind, and they are priced by the linear foot, not the square.
Where It Fails First: Drift Pockets and Dock Edges
On a tilt-up warehouse the walls rise past the roof line, and that parapet turns the downwind side into a trap. Snow blows across the open field, drops behind the wall and builds into a drift that can run far deeper than the snow on the rest of the roof. Saturated snow weighs roughly 20 pounds per cubic foot, so a deep drift is a concentrated weight on one strip of deck.
That strip also holds meltwater the longest. When the drift thaws at noon and refreezes at night, water works into the wall flashing and the first seam in reach. In the Riverbend Commerce Park tilt-ups in Post Falls, the strips behind the panel walls are the first places we walk. Dock-door canopies and rooftop unit curbs form the second set of trouble spots.
Alternates: What the Owner Can Take Out
We break a warehouse bid into a base scope and a short list of alternates so the owner decides what stays. Common alternates for these buildings:
- Added insulation thickness for the energy code, as its own line
- Walkway pads from the roof hatch to each rooftop unit
- Snow guards or a snow-retention layout over dock and office entries
- Overflow scuppers where the main drains could clog
- A longer manufacturer warranty term if the owner wants one
Each one has a price and a reason. None is hidden in the field number. An owner who is holding the budget tight can cut a walkway pad, but should not cut an overflow scupper on a roof with parapets on four sides.
Schedule and Snow Window: When the Roof Can Open
The real scheduling limit on a warehouse is weather, not crew size. Adhered and torch-applied systems need dry surfaces and workable temperatures, and Coeur d'Alene sees a record low of minus 30 F and a January mean near 31 F. Most replacement work lands between spring thaw and the first hard freeze, and we plan the dry-in so no section of deck sits open overnight.
Warehouses keep operating during reroofing, which sets the sequence. We work in bays, protect racking and product beneath the open section, and agree on a hold point for each phase so a tenant can confirm their goods are covered before the next section opens. For Post Falls and Rathdrum Prairie buildings the first call is usually about the dock schedule, not the membrane.
Closeout: What You Get at the End
When the roof is done, the owner receives a written scope showing what was installed, drain and edge details, and photos of the deck conditions we found under the old system. If a change order came up, it is on the record with its reason. Plan on a second look after the first heavy snow, because that is when a new drift pocket shows whether the layout works. If it does not, the fix is a drain, a crickets-and-saddle adjustment or a snow guard, priced as a change order with the reason attached, and the owner approves it before the crew returns. We would rather correct a drift pocket in November than patch a seam in February. A replacement and a recover both finish this way, and TPO is the usual membrane on roofs this open. A smaller flex industrial unit closes out on the same terms, as does a warehouse in Post Falls, and a distribution center adds the dock-schedule record on top. If the roof is old and the budget is still open, a roof inspection comes before any of these.
Commercial Roofing Questions
Can we recover instead of tearing off?
Only if the insulation underneath is dry and the deck is sound. A moisture survey tells us, and the answer can differ between the north and south halves of the same roof. Where a recover is allowed, it saves the tear-off and disposal lines.
How much snow is too much for a flat warehouse roof?
Twenty inches of saturated snow weighs a lot more than twenty inches of dry powder, since the City guidance puts wet snow near 20 pounds per cubic foot. Drifts behind parapets matter most. If the roof shows sagging, ponding after melt or tight doors below, call before shoveling.
Do you work while the warehouse is running?
Racking, forklifts and dock doors stay in use while we work in bays. Product under an open section gets protected before the membrane comes off, and we set a hold point for each phase.
What does the edge metal line cover?
Coping, drip edge, gutter and fascia at the perimeter, the first place a big wind goes to work. It is priced per linear foot and fastened to the code wind speed.
What should the bid show for drains?
Each drain, scupper and overflow, with its count and any slope work. Two bids that disagree on drains are not bidding the same roof.