What to Expect When a Standing Seam Roof Goes On in Oregon

What happens before the crew shows up at an Oregon house?

The first thing that moves is paper, not shingles. A re-roof in Oregon is permitted through whichever jurisdiction the house sits in, which means the City of Portland for most of Multnomah County, Clackamas or Washington County for the suburbs, and the county building department for places like Warren, Scappoose, or Hood River. The installer pulls the permit under the Oregon Residential Specialty Code, and the contractor's CCB number should be on the application. Interlock Metal Roofing (PNW) works under Oregon CCB #130826, and you can check any license on the CCB website before signing. While the permit is in process, the panels are ordered to length. Standing seam is not a stock product pulled off a shelf; each panel is cut to the exact ridge-to-eave run of your roof, so the estimator's measurements are the measurements the roof will be built from. On a Portland foursquare with two hips and a dormer there may be a dozen different panel lengths, and materials usually arrive a day or two before the crew. One more thing gets settled before anyone climbs a ladder: whether the existing roof comes off. Many Willamette Valley houses carry a second layer of asphalt already, and standing seam is unforgiving of an uneven deck. Broad flat pans telegraph every lump beneath them and make oil canning worse. In practice that means a full tear-off on nearly every Oregon standing seam job, and the disposal is part of the quote.

How does Oregon weather decide when the roof goes on?

A tear-off opens the house to the sky, so the schedule is built around the rain. Multnomah and Clackamas counties average about 58 inches a year, most of it between October and May, and Benton County sits closer to 60. West of the Cascades the reliable window for a full tear-off and re-deck runs from roughly June into early October. Good crews still work the shoulder seasons, but in sections, opening only what they can dry in the same day. The coast is harder. Tillamook County sees 81 inches of rain and gusts to 85 miles per hour, Clatsop 72 inches with gusts to 91, and a tarp on a stripped deck in a coastal blow is a liability. Coastal jobs get staged smaller. East of the Cascades the problem flips: Wasco County gets only 18 inches of rain, so the working season is long, but the Gorge wind at The Dalles and Hood River makes handling 20-foot aluminum panels a two-person job on calm mornings and a no-go on gusty afternoons. This should not scare you off a fall or spring install. It should tell you that a crew that promises a November tear-off in Eugene with no weather plan has not stood on many Lane County roofs. A realistic schedule for a typical single-family home is five to ten working days, stretched by rain days, and the contract should say what happens when the weather stops work.

What goes on the deck before the first panel?

Once the old roof is off and in the dumpster, the crew walks the bare deck. Decades of damp north slopes under moss-choked asphalt leave soft spots at the eaves, delaminated plywood around old chimney flashings, and skip-sheathing under original cedar on pre-war Portland bungalows. Rotten sections are cut out and replaced, and skip-sheathing gets a layer of solid sheathing over it, because standing seam needs a continuous, flat deck to clip to. Ask to see the deck before it is covered, or ask for photos. Next comes the water barrier, and this is where a Hood River house and a Beaverton house get different roofs. A self-adhering ice-and-water membrane goes on at the eaves, in every valley, and around penetrations. In Washington County, with 11 inches of snow and 37 freeze-thaw days a year, that is good practice. In Hood River County, with 76 inches of snow and 55 freeze-thaw days, it is the difference between a dry ceiling and a March leak, because meltwater refreezing at a cold eave backs up under any roofing. The same applies in the Mt. Hood and Cascade foothills. The rest of the deck is covered with a synthetic underlayment, lapped shingle-style and fastened with cap nails, not staples. Synthetic underlayment does not wrinkle when wet the way felt does, which matters when a shower rolls through Salem mid-afternoon. At the end of this stage the house is dried in and can sit through a rain day.

How are the panels and seams actually put together?

Edge metal goes on first: drip edge at the eaves, and rake trim along the gable ends. These direct water into the gutter rather than behind the fascia, and they are the pieces most often skipped on cheap jobs. Then the panels are laid out. Each aluminum panel runs from ridge to eave in a single piece, set square to the eave so the seams stay straight all the way up. A panel that starts a quarter inch out of square is an inch out by the ridge on a long Willamette Valley farmhouse roof. Panels attach to the deck with concealed clips. The clip is screwed through the underlayment into the sheathing, and its top engages the raised seam of the panel. On an Interlock aluminum system these are floating clips, meaning the panel can slide slightly within the clip as it expands and contracts with temperature. Aluminum moves more than steel, and a black panel on a south-facing slope in The Dalles in July moves a lot. No fastener passes through the visible surface of the roof anywhere on the field. The next panel locks over the first at the seam. Depending on the profile the seam is either snapped closed by hand or folded shut with a mechanical seamer run up the length of the joint. Then the detail work begins: valleys, sidewall and headwall flashings where the roof meets a dormer or a second-story wall, pipe boots, chimney saddles, and the ridge cap with its closure strips. On the documented Warren job in Columbia County, 22 squares of black standing seam went on in May 2025, and the flashings took longer than the panel field.

What should a Portland or Hood River homeowner check each day?

You do not need to inspect the work, but you should look at it. On tear-off day, look at the tarps over the landscaping and whether the dumpster is where you agreed. At the end of the first day the deck should be either dried in or covered with secured tarps, and if the forecast is wet and the tarps are loose, say so that evening rather than after the ceiling stains. Ask for the count of replacement sheathing sheets, since that is usually a per-sheet charge. Once the underlayment is on, walk the perimeter of the house. In Hood River or the Cascade foothills, confirm the ice-and-water membrane is visible at the eaves and in the valleys, not just the synthetic underlayment. As the panels go on, sight up the seams from the ground; a wavy seam is a layout error that is cheaper to fix on day three than day seven. On the last day, three things. First, snow guards. On a Multnomah County roof with 19 inches of average snow, they are usually only needed above a door or a walkway. In Hood River, The Dalles, or the Mt. Hood foothills, a full standing seam roof will shed its snow load in one sheet, and guards above entries, decks, gas meters, and heat pumps are not optional. Second, check that every penetration has its flashing and that the ridge cap is closed. Third, get the paperwork: the signed-off permit inspection, the manufacturer's warranty registration, and the finish warranty. The Alunar 70 percent PVDF coating carries a 30-year finish warranty, and the material warranty is lifetime to the original owner. Those documents matter when you sell.

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