Can You Put a Metal Roof Over Cedar Shake in Oregon?

Can you put a metal roof over cedar shake in Oregon?

Not directly, and the reason is what is under the shake rather than the shake itself. Cedar shake went onto a lot of Oregon houses from the 1960s through the 1990s, and it is still the roof on many homes in Lake Oswego, the Portland West Hills, the Cascade foothills above the Willamette Valley, and the shingle-style houses along the coast. Nearly all of it was nailed to skip sheathing, which is 1x4 or 1x6 boards spaced several inches apart so the shakes could dry from below. That spacing is what let cedar breathe, and it is also why there is no continuous surface to fasten a metal roof to. On an asphalt roof you have a plywood or board deck under the shingles, and a metal re-cover over one layer is a normal job. On shake you have gaps between boards, shakes that have cupped and split, and a surface that varies by half an inch or more from one course to the next. Metal panels laid over that would telegraph every hump, and the clips and fasteners would find air as often as wood. So the honest answer for an Oregon shake roof is that the shake comes off and the deck gets built before any metal is considered.

What do Oregon crews find when the shake comes off?

West of the Cascades, rot and moss. Multnomah and Clackamas counties average about 58 inches of rain a year, Benton County about 60, and Lane County about 56, and most of it falls between October and May when north-facing slopes never fully dry. Cedar shake holds that water in its grain and in the gaps between shakes, and moss roots straight into it. By the time a Lake Oswego or West Hills homeowner calls about a leak, the shakes on the shaded side are often soft enough to push a thumb into. Under the shake, the skip sheathing is usually in mixed condition. Boards along the eaves and under valleys have often gone punky where water sat, and the rafter tails below them sometimes need sistering. On coastal homes in Tillamook, Lincoln and Clatsop counties, where rainfall runs 71 to 81 inches and wind drives water sideways, the damage tends to be worse and to reach further up the slope. None of this is a surprise to a crew that has done shake tear-offs in Oregon, but it is a reason the estimate should include an allowance for board replacement and a visit to the roof before numbers are final, since nobody can see the deck through the shake.

What does Oregon code require when you replace cedar shake with metal?

The Oregon Residential Specialty Code, which is the state's adopted version of the residential building code, does not permit a new roof covering over a deck that cannot support it, and skip sheathing does not meet the solid-deck requirement for interlocking metal shingles or standing seam. In practice that means the job is a tear-off, then solid sheathing over the existing skip boards or in place of them, then underlayment, then the metal. The sheathing is typically plywood or OSB nailed through to the rafters, and ice-and-water membrane goes at eaves and valleys where the code and the local climate call for it. This is permitted work in every Oregon jurisdiction. Portland, Lake Oswego, Beaverton and the counties each issue their own roofing permits, and the inspector will want to see the new deck and the fastening before the metal covers it. Confirm your contractor holds an active Oregon CCB license and pulls the permit under that license rather than asking you to do it as an owner-builder. The re-deck adds labor and material that an asphalt re-cover would not carry, so a shake-to-metal quote in Oregon will be higher than the same square footage over asphalt, and a quote that does not mention new sheathing is not describing the job.

Does replacing shake change the fire rating in an SB 762 wildfire zone?

Yes, and for many Oregon homes that is now the deciding factor. Oregon's SB 762 wildfire hazard map and the home-hardening rules that follow it apply on the east side, in southern Oregon, and along the wildland edge of the Cascade foothills, which is exactly where a lot of cedar shake sits. Untreated wood shake is the roof insurers and fire officials most want gone. Replacing it with aluminum shake installed as part of a Class A fire-rated assembly, which uses a fire-resistant underlayment beneath the metal, moves the roof from the most combustible covering to the highest rating the test method offers. The rating is for the assembly, not the shingle on its own, so the underlayment layer is not optional in a hazard zone. Homeowners in the Hood River valley, around the Mt. Hood foothills, and in the foothills east of Salem and Eugene should ask for the Class A build-up in writing. Some carriers are reluctant to write or renew policies on shake in mapped hazard areas, and a non-combustible roof with UL 2218 Class 4 impact rating can change that conversation, though you should ask your carrier what applies to your address rather than assume a discount.

What replaces cedar shake in Oregon and how does the install go?

Most homeowners who loved the look of cedar want to keep it, and the aluminum shake profile is the look-alike replacement. It carries a deep wood-grain texture and a heavy shadow line, comes in the greys and browns weathered cedar turns, and interlocks on all four sides so wind in the Gorge or on the coast has no free edge to lift. It weighs a fraction of what wet shake weighs, which the older rafters on a foothills home appreciate. It does not rot, moss has nothing to root into, and it will not need the wash-and-treat cycle Oregon shake demands every few seasons. It also does not look exactly like fresh cedar up close, and on a low-slope roof in flat light a homeowner standing in the driveway will see a metal roof, not a wood one. A recent job shows the sequence. In April 2026 a Cloverdale home in Tillamook County, in 81 inches of annual rain and gusts to 85 mph, had its shake stripped, the deck sheathed solid, and 34 squares of Deep Charcoal aluminum cedar shingle installed. Lake Oswego, where shake roofs are still common, has 19 of these roofs on record since 1999. The tear-off and re-deck take longer than an asphalt job and the yard gets a dumpster and a lot of old cedar for a week, but once the metal is on, the roof carries a lifetime material warranty and the maintenance conversation is over.

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