For most Oregon homes, the best rain-ready siding is James Hardie fiber cement, with real cedar a strong second choice if you will keep up the finish. Both work, but only when the installation is right: flashing, a water-resistive barrier, a drainage gap behind the boards, and proper clearance at roofs and the ground. In Oregon, how siding is put on matters more than what brand name is on the box.
What rain does to a house here
Portland-area rain is steady rather than dramatic. The National Weather Service’s Portland climate book describes about 35 to 37 inches a year at the airport and roughly 60 inches in the West Hills, with most of it falling between mid-October and mid-May. Out east, wind-driven rain coming off the Columbia Gorge pushes water sideways into joints, behind trim and under window sills. Add moss, ice storms in the Gorge corridor, and a wet spring, and a wall may stay damp for months.
Siding is the first layer of defense, not the only one. Water gets behind almost every wall eventually. The real question is whether it can get back out.
Fiber cement (James Hardie)
Fiber cement is a cement, sand and cellulose fiber board. James Hardie states that its siding is noncombustible and resists moisture damage, and does not attract termites or woodpeckers.
Strengths in Oregon:
- It does not rot the way wood does, so the bottom courses and window surrounds hold up better.
- It resists fire and embers, which matters with wildfire smoke seasons getting longer.
- Factory-applied ColorPlus finishes avoid repainting on a short cycle. Hardie lists a 30-year non-prorated product warranty and a 15-year limited finish warranty, with conditions in the warranty documents.
- Hardie offers cedar-look options (see below), so you do not have to give up the wood look.
Cautions: it is heavy, it must be cut and handled with dust control, and the joints and edges must be flashed and sealed per the manufacturer. Cut edges that are left bare can still absorb water. Hardie’s documents call for clearance gaps at roof lines and decks; follow the current Hardie installation instructions.
Real cedar
Western red cedar naturally resists decay and insects better than most woods, and it is easy to repair: a damaged board can be cut out and replaced. Many 1950s to 1970s Oregon ranches and Craftsman homes wore cedar for decades.
Cedar’s price is upkeep. The Western Red Cedar Lumber Association says siding stains generally last 3 to 5 years and recommends gentle cleaning rather than pressure washing. Skip a few cycles in a wet climate and moss and mildew will move in. See our Hardie vs. cedar comparison for the trade-offs.
What about vinyl and LP?
Six-Point does not install vinyl or LP SmartSide. Dave sticks to two materials he trusts in Oregon rain: fiber cement and real cedar. Vinyl is a thin plastic skin that can crack and fade and does not give the look of real wood. Engineered wood products like LP rely on edges and finish staying sealed, which is a lot to ask of a wall in a wet climate. Plenty of homeowners choose them anyway; they are simply not what Dave installs.
The install matters more than the material
A premium siding on a bad install will fail. These are the details that decide it.
Drainage and a water-resistive barrier
The Oregon Residential Specialty Code requires exterior walls to be built so water that gets in can drain out. In plain terms, that means a water-resistive barrier plus a drainage space of at least 1/8 inch behind the veneer, unless an approved drainage-enhanced barrier is used. Our rainscreen and house wrap guide explains it.
Flashing
Window and door heads, sills, belly bands, and roof-to-wall intersections each need their own flashing. Kick-out flashing at the bottom of a roof edge sends roof runoff away from the wall. A missing kick-out lets roof runoff run straight down the wall and soak the same few boards every storm.
Clearance
Siding should not sit tight against shingles, decks or soil. Leave the gaps the manufacturer and local code call for so water drains and dries rather than wicking up.
Fasteners and caulk
Use the right nails at the right spacing, hit the framing, and use sealant where the manufacturer says to, not as a patch for bad flashing.
Moss, shade and the north wall
Moss and algae grow on any siding that stays damp, including fiber cement and painted cedar. They are mostly a cosmetic problem on fiber cement but can hold moisture against cedar. Trimming back shrubs and tree limbs, keeping gutters flowing, and washing the wall gently every year or two does more than any product choice. Walls that never see the sun, usually the north side, are where you will notice problems first.
Wind and the Gorge
East County and Corbett get wind-driven rain and, at times, ice storms funneling out of the Columbia Gorge. Wind pushes water sideways into laps and trim joints. That is one more reason the barrier behind the siding and the flashing around openings matter as much as the boards on the front.
Quick answers
- Is fiber cement good in rain? Yes. It does not rot, and it takes a factory finish well.
- Is cedar good in rain? Yes, with regular maintenance and a drainage gap.
- Will siding alone keep my house dry? No. The wall system does.
- How do I know my current siding is failing? See our signs of dry rot guide.
- What does it cost? See the cost guide.
Talk to Dave
Dave Shaffer is a second-generation sider with about 40 years of experience and is on every Six-Point job. He installs James Hardie fiber cement and real cedar across the Portland metro and East County, including Corbett and Gresham. CCB #153635, licensed, bonded and insured.
Call or text Dave: 503-260-7647. Free estimates.