PBR vs. R-Panel vs. Standing Seam: Choosing Metal Building Panels for Spokane Snow (2026)

Short answer: most pre-engineered metal buildings around Spokane get PBR panels on the roof and either PBR or R-panel on the walls, and that's a sound, budget-friendly choice when the roof has enough pitch and the laps are sealed. A standing seam roof costs more but has no screws through the face of the panel, lets the steel expand and contract on clips, and can go on flatter roofs. In snow country like ours, the bigger questions are roof pitch, where the snow will slide, and whether the panel profile is right for the job. Here's how the common metal building panels compare, with the code and spec-sheet numbers behind them.

The three panels you'll see on a metal building quote

Most metal building and post-frame suppliers in the Inland Northwest offer the same basic families:

• PBR (purlin bearing rib): an exposed-fastener panel with 36-inch coverage, 1-1/4-inch major ribs every 12 inches, and a purlin bearing leg about 1 inch long at the underlap that rests on the purlin
• R-panel: the same profile as PBR without the purlin bearing leg. Suppliers like AB Martin and Cumberland Supply recommend it for sidewalls, not roofs, because of that missing leg
• Standing seam: a concealed-fastener roof. Panels lock together at raised seams and are held down with clips under the seam, so no screws go through the face of the panel. Vertical-leg profiles commonly have a 2-inch seam on 16-inch wide panels; trapezoidal standing seam roofs (SSR) are made for simple sloped roofs without hips or valleys

You'll also see "ag panel" or similar lighter exposed-fastener profiles, mostly on pole barns and re-roofs.

What the spec sheets say

Typical published figures for PBR and R-panel:

• Gauge: 26-gauge is standard; 24-gauge is the heavier upgrade
• Span over open framing: 26-gauge panels span up to about 4 feet between supports and 24-gauge up to about 5 feet (AB Martin and Cumberland Supply)
• Steel strength: one supplier's sheet lists R-panel steel at 50,000 psi minimum yield and PBR at 80,000 psi (Live Oak Metal)
• Coating: Galvalume (aluminum-zinc coated) steel, usually AZ50 under paint or AZ55 with a clear acrylic coat for bare "mill finish" panels
• Minimum slope: most PBR sheets list 1:12; Nash Building Systems lists 1/2:12 for its R and PBR panels over open purlins or solid deck

Those span limits are why panel choice, gauge and purlin spacing are designed together. In a PEMB, the manufacturer's engineer sets the purlin spacing for your site's snow load, then picks a panel that can carry it.

What the building code says about roof slope

The International Building Code, adopted in Washington, sets minimum slopes for metal roof panels in Section 1507.4.2:

• Lapped, exposed-fastener panels without lap sealant: at least 3:12
• Lapped panels with lap sealant: at least 1/2:12, with sealant applied per the manufacturer's instructions
• Standing seam: at least 1/4:12

The code also requires metal roof panels to go on a solid deck unless the panel is designed for spaced supports, which is exactly what PBR over purlins is. Most metal building roofs in our area are pitched well under 3:12, so sealed laps aren't optional on a PBR roof. We use sealant tape and stitch screws at the laps, which suppliers also recommend for leak protection.

Spokane snow changes the conversation

Panel choice can't be separated from snow. Spokane County publishes a 39 psf base ground snow load with a 30 psf minimum roof snow load, and notes that some parts of the County reach 150 psf. Spokane International Airport averages 45.4 inches of snow a year (NOAA 1991–2020 normals).

Metal roofs count as "slippery" in ASCE 7, the load standard the building code uses. That matters two ways:

• Lower design load, sometimes: a sloped, unobstructed metal roof with room below the eave for snow to slide off can use a reduced snow load. The Army Corps of Engineers' cold regions lab notes a well-insulated 6:12 metal roof with an unobstructed slippery surface carried only about 66% of the design load of a similar roof that holds its snow under the 1995 edition of ASCE 7
• Snow guards remove that credit: snow guards, parapets and other obstructions turn the roof back into a non-slippery roof for design. Structure magazine's metal building snow load article and the same lab's guidance both say retained snow must be designed for, and sliding snow onto a lower roof has to be checked separately
• Plan where it lands: sliding snow off a steep metal roof can bury a walk door, shear off a vent stack or pile up on a lean-to roof. We keep man doors on the gable ends or under a protected overhang where we can, and talk through snow guards before the building is ordered so the engineering matches

Exposed fastener vs. standing seam in our climate

• Exposed-fastener PBR: lower cost, faster to install and works as both roof and wall panel. The panel is pinned at every screw, so it can't move freely with temperature swings, and the rubber washers on the screws age over time. Plan on checking screws during routine maintenance
• Standing seam: no face penetrations for water to find, and the panels float on clips as they expand and contract. It's the better choice for a low-slope roof, a heated building or a shop attached to living space, and a common upgrade for barndominiums
• Walls: PBR or R-panel is the norm on walls either way. Wall panels don't hold snow or standing water, so the purlin bearing leg and concealed fasteners matter much less there

Don't forget what's under the panel

Condensation is the other way metal panels fail early. Warm, moist air hitting cold steel drips onto everything inside. Every heated shop needs a continuous vapor retarder on the warm side of the insulation. Our metal building insulation guide covers the energy code and condensation in detail, and our snow load article explains how loads drive the frame.

How Raven handles it

• Engineered package: we aren't tied to one manufacturer. We source each building from whichever manufacturer can deliver fastest, and the panel, gauge and purlin spacing come stamped for your parcel's snow load
• Your choice of roof: sealed-lap PBR as the value option, standing seam where pitch, heat or looks call for it
• Snow plan: door locations, overhangs and snow guards settled before the order goes in
• Cost: Raven's installed price for a pre-engineered metal building runs about $60 to $75 per sq ft, with electrical, plumbing and utility hookups extra. Standing seam and other upgrades are quoted per project

Not sure what size you need? Our 30x40 vs. 40x60 vs. 40x80 sizing guide helps, and our PEMB lead time guide covers the timeline.

Get a metal building quote

Call 509-350-2016 or request a free quote with your size, door layout and address, and tell us whether you're leaning PBR or standing seam. See our steel building services.

Sources

• Installed pricing: Raven Buildings' current going rate for the Spokane area
• AB Martin, Commercial Panels (PBR and R-panel specs)
• Cumberland Supply, Commercial Metal Panels
• Live Oak Metal, R and PBR Panels sale sheet
• Nash Building Systems, Building Panels (PBR, SSR, SSA)
• IBC 2021 Section 1507.4, Metal Roof Panels (UpCodes)
• Structure Magazine, Design Snow Loads and Metal Buildings
• US Army Corps of Engineers CRREL, Snow Guards for Metal Roofs
• Spokane County Building FAQ (snow load)
• NOAA NCEI 1991–2020 Normals, Spokane International Airport