Gresham sits east of Portland in Multnomah County, and the roofing environment is the same Pacific Northwest moisture pattern that dominates the wider metro. The city collects the same 36-plus inches of annual rain, the same extended overcast season, and the same relentless moss, algae, and lichen pressure that defines every Willamette Valley roofing conversation.
The dominant residential roof types across Gresham are asphalt shingle on the newer 1980s-through-2000s stock and cedar shake on some of the older homes across the historic Gresham core. The failure modes are what they always are in the PNW — moss establishment on north slopes lifting shingle edges, cedar shake rot on shaded elevations, and moisture damage at every flashing detail not installed to Pacific Northwest standards.
Moss is the through-line problem
Untreated moss working under shingle edges is the leading cause of premature shingle replacement across western Oregon. On a Gresham re-roof, a zinc or copper strip installed at the ridge suppresses moss on slopes below — the cheapest single upgrade in this climate.
Cedar shake in older neighbourhoods
Older Gresham homes still carry cedar shake roofs. Pacific Northwest cedar delivers 20 to 40 years depending on exposure and maintenance. At end-of-life, the decision is often cedar versus modern composite or metal alternative.
Flashing detail carries the roof
Because water sits on Gresham roofs for so much of the year, any flashing imperfection is exercised daily. Step flashing at walls, chimney counterflashing, valley underlayment, and eave drip edge should all be first-class specification items.
Occasional serious winter events
Gresham does not see routine Midwest ice-and-snow punishment, but occasional serious winter storms — including the February 2021 ice storm that affected much of the metro — produce ice-and-freeze damage on any weakness in the roof assembly. Ice-and-water barrier at eaves is worth specifying.
Foothill parcels see more winter
Homes climbing toward Mount Hood in eastern Gresham see more snow accumulation than the metro floor. Ice-and-water barrier and continuous ventilation matter more on these homes.
City of Gresham permits
The Gresham Urban Design & Planning Department issues re-roof permits, and inspection includes flashing and ventilation. The permit should be a line item on the written quote.