Do I need a permit for an attached deck in
Sherwood, Oregon?

Sherwood attached deck permits—the key details

Sherwood requires a permit for every attached deck, with no exemption threshold. Oregon Building Code R507.1 applies in full, meaning any deck that is attached to a house (ledger-bolted to the rim band or band board) triggers plan review. The city's Building Department explicitly states on its website that even a small 8x10 deck attached to the back of a house must be permitted. This is markedly different from some other Oregon cities that exempt decks under 200 square feet and under 30 inches above grade. Sherwood's conservative approach stems from documented settlement issues in the Willamette Valley with shallow frost protection—local soil boring records show that a 12-inch footing (adequate for frost line) can still fail if the deck load isn't properly transferred to the beam and posts. The ledger-board connection is the most-cited deficiency in rejected plan sets: Sherwood inspectors will reject any ledger flashing detail that doesn't match IRC R507.9 exactly, including a 1/2-inch exterior-grade rim-board rim, a water-resistive barrier behind the ledger, and flashing that extends 4 inches up the band and laps over the exterior siding.

Footing depth in Sherwood varies dramatically depending on location. West of Oregon Route 99W (the main north-south corridor), frost line is 12 inches; east of the route toward Sunrise Valley, frost line jumps to 30 inches or more in the foothills. The city's standard practice is to require frost-depth confirmation via a building-permit application that includes the exact site address, so the plan reviewer can cross-reference the city's frost-depth map. If your footing design shows 18-inch holes but your lot is in the eastern hills, the plan will be rejected with an RFI (Request for Information) asking you to justify deeper footings or provide a soil-boring report. Posts must sit on frost-protected footings via a bolt-down connection to a concrete pier that extends below the frost line. Use of ground-contact pressure-treated lumber (UC4B or UC4A per AWPA) is mandatory for any wood in contact with soil. A common mistake is to dig one footing depth across the entire deck frame; if part of your deck sits on a hillside slope, you may have multiple frost depths to design for, and the city will ask for section views showing each footing condition.

Ledger-board flashing is non-negotiable in Sherwood plan review. IRC R507.9 requires a through-flashed or W-flashed ledger that sheds water down and away from the house band board. The flashing must be at least 26-gauge galvanized steel or aluminum, installed under the house rim board (above the exterior siding) so water cannot pool behind it. Many homeowners and builders attempt to use caulk or sealant as a substitute for flashing; Sherwood will reject this outright. The bolts connecting the ledger to the rim must be 1/2-inch galvanized or stainless-steel lag bolts or bolts with washers and nuts, spaced 16 inches on center. The house foundation must be able to carry the lateral load of the deck (wind and seismic); if your deck is cantilevered more than 18 inches from the house or if the rim board is a single 2x10, Sherwood's structural reviewer may require a licensed engineer to stamp the connection detail. This is where owner-builder projects often hit a snag: Sherwood accepts owner-builder applications for single-family decks only if the owner is the permanent occupant AND the design is straightforward (under 200 sq ft, no cantilever, simple shed roof or open top). Anything larger or more complex requires a licensed contractor or engineer.

Three Sherwood deck (attached to house) scenarios

Frost depth and footing design in Sherwood—why 12 inches is not enough

Sherwood straddles two distinct frost-depth zones, and this is the single biggest reason the city is strict about plan review for attached decks. West of Oregon Route 99W, the Willamette Valley floor has a frost line of 12 inches; east of the highway toward Sunrise Valley and the foothills, frost line rises to 30 inches or more. A deck footing that is 12 inches deep will fail if it is actually in the 30-inch zone, or if it is 12 inches in the Willamette but installed without proper bearing on undisturbed soil below the frost line. The International Building Code (IBC 2020, adopted by Oregon with state amendments) requires footings to be set below the frost line to prevent 'frost heave'—the expansion of water-saturated soil as it freezes, which can lift an entire deck and snap bolts or damage the ledger connection. Sherwood's Building Department has seen this failure repeatedly: a deck installed in winter with a seemingly adequate footing fails the following spring as the ground thaws and the post settles back down, creating a gap between the ledger and the house.

The city's solution is to require you to provide your site address on the permit application so that the plan reviewer can cross-reference it against the city's frost-depth zoning map. If your lot is in the eastern hills, the reviewer will expect 36-inch footings (30-inch frost line plus a 6-inch safety margin). If your lot is in central Sherwood near the Willamette floodplain, the reviewer will accept 18-inch footings (12-inch frost line plus 6 inches). Do not guess on this—call the Building Department and ask them to confirm the frost depth for your address before you design the footing. Many contractors assume 18 inches statewide; Sherwood's plan reviewers will reject this assumption if your lot is in the foothills.

Footings must be placed on undisturbed native soil or engineered fill. If you dig a hole and find clay, sand, or gravel that was previously disturbed (common in developed neighborhoods), you cannot simply pour concrete into that hole. Sherwood's standard practice is to require at least 6 inches of below-frost bearing on undisturbed soil. If your lot has been graded or filled, the inspector will watch your footing pre-pour and may ask you to dig deeper or to bring in engineered fill. The cost of a soil-boring or engineer consultation is $500–$1,500; it's cheaper to address this during permit review than to have the deck fail after completion. Use frost-protected shallow foundation (FPSF) design if you want to reduce footing depth, but this requires engineer design and sealed plans—not typically approved for a simple deck.

Ledger flashing and the reason Sherwood rejects 90% of rejected plans

The ledger-board flashing detail is the most commonly rejected item in Sherwood deck permit applications. The IRC R507.9 requirement is precise: the flashing must be a through-flashed or W-flashed metal piece installed between the house rim board and the exterior siding, extending at least 4 inches up the rim band and lapping over the siding to direct water down and away. Many builders and homeowners attempt to 'caulk' the joint or use sealant instead of flashing, believing that a good bead of silicone will keep water out. Sherwood's inspector will reject this every time. Water will work its way behind the siding, rot the rim board and band board, and eventually cause the ledger to pull away from the house during a heavy snow load or earthquake. This failure mechanism has caused serious injuries in Oregon.

The proper ledger setup in Sherwood requires you to: (1) expose the rim board on the house by removing or pulling back exterior siding; (2) install through-flashing (26-gauge galvanized steel or aluminum, often pre-fabricated by Simpson or similar) under the rim board, on top of any water-resistive barrier (house wrap); (3) re-side or flash over the top of the through-flashing so water sheds down; (4) bolt the ledger to the rim with 1/2-inch galvanized lag bolts or bolts with washers and nuts, spaced 16 inches on center; (5) seal the bolt penetrations with sealant. Your plan drawings must show a cross-section detail (side view) of this assembly at 1/2-inch or 1-inch scale. If your drawing shows the flashing but does not clearly indicate where the rim board is, how the flashing connects, and what material it is, the plan reviewer will request clarification. Sherwood's online portal allows you to submit revised plans digitally, but expect one RFI (Request for Information) minimum on the ledger detail alone.

The cost and time impact of redoing the ledger flashing after construction is enormous. If you frame the deck without a proper ledger flashing detail, Sherwood's inspector will stop the work and require you to remove the deck, install the flashing correctly, and reassemble it—easily a $2,000–$5,000 do-over. Get the flashing detail stamped and approved before you buy materials. If you are uncomfortable drawing the detail yourself, ask your contractor to provide it, or hire a draftsperson or engineer to draw it ($200–$400). It is cheaper than a stop-work order.

Common questions