Seattle Why We're Writing This Page
Homeowners in Seattle ask us about LP SmartSide often enough that we think it deserves a straight answer instead of a sales pitch. We don't install it, and we think you should know exactly why before you sign a contract with anyone — us or another contractor. This isn't a takedown of the product. It's an explanation of the trade-offs we ran into over years of exterior work in King County, and why those trade-offs led us to standardize on James Hardie fiber cement instead.
LP SmartSide is a legitimate, widely used engineered wood siding product. It has real advantages, and plenty of homes around the country wear it well. Our position is about what happens to that product specifically in our climate, under our rain load, and under our moss and mildew pressure — not a blanket claim that it's a bad product everywhere.
What LP SmartSide Gets Right
Credit where it's due. LP SmartSide is an engineered wood product — strand-based substrate treated with zinc borate and resin, then coated with a factory primer. Compared to old-school untreated wood siding, it's a real step forward:
- Lighter and easier to handle on site than fiber cement, which can speed up labor on some jobs
- Reasonably impact-resistant for an engineered wood product
- Lower material cost than fiber cement in most markets
- Wide range of textures, including lap, panel, and shake profiles that mimic traditional wood
- Backed by a manufacturer with decades in engineered wood products
If you live somewhere dry, with well-maintained gutters and low humidity, LP SmartSide can perform for a long time. The issue isn't the factory product — it's what happens once that product meets the Pacific Northwest.
The Core Material Difference: Wood-Based vs. Fiber Cement
LP SmartSide is still, at its core, a wood product. It's engineered — strand board pressed and bonded with resin — but wood fibers are wood fibers. They absorb moisture, and they can swell, delaminate at the edges, or break down over time if water gets past the coating. Fiber cement, which is what James Hardie makes, is cement, sand, and cellulose fiber cured under pressure. It doesn't have organic wood content that can rot, and it's not attractive to moisture the same way.
That distinction matters everywhere, but it matters more in a climate like ours. Seattle and King County get sustained wet seasons, not just occasional storms. Materials here don't get a chance to fully dry out between rain events for months at a time.
Edge and Cut-End Vulnerability
Engineered wood siding is most vulnerable at cut ends, seams, and fastener penetrations — anywhere the factory coating has been breached on site. Every field cut on an LP SmartSide job needs to be sealed correctly with the manufacturer's approved sealant, every time, with no exceptions. In our experience, that's a lot of small opportunities for a crew to get it right 95% of the time and wrong 5% of the time — and the 5% is where the problems start, usually years down the road when it's much harder to trace back to an installation shortcut.
Where Our Climate Makes the Difference Real
Seattle's exterior siding doesn't just deal with rain — it deals with driving rain that hits horizontally in a wind-driven storm, salt air pulled in off Puget Sound, and a moss and mildew season that can run most of the year on a shaded, north-facing wall. That combination is tough on any siding, but it's specifically hard on a wood-based product because:
- Driving rain forces water into laps, joints, and butt seams under wind pressure, not just gravity
- Salt air accelerates the breakdown of coatings and fasteners over time
- Moss and algae hold moisture against the siding surface for extended periods, rather than letting it shed and dry
- Long gray stretches mean less UV drying time between rain events compared to sunnier climates
None of that is exotic information — it's just what King County weather does every year. But it's exactly the profile of conditions that stresses an engineered wood product's weak points: the cut ends, the seams, and any spot where the factory treatment has been compromised on site.
Installation Sensitivity: Why the Installer Matters More Than the Product
We'll be direct about this: a lot of LP SmartSide problems we've seen called in for repair estimates trace back to installation, not the product itself. That's true of most siding, but engineered wood has less margin for error than fiber cement does. Correct installation requires:
- Sealing every field-cut edge with the specified sealant before installation, not after
- Maintaining proper clearance from grade, decks, and roof lines so water can't wick up from below
- Correct fastener placement and depth — overdriven nails create a moisture entry point at every course
- Proper flashing and drainage plane behind the siding so incidental moisture has somewhere to go
Fiber cement has some of these same requirements, but it has more forgiveness built into the material itself. With engineered wood, a rushed crew on a production schedule can produce a wall that looks identical to a correctly installed one on the day of completion — and the difference only shows up five or ten years later.
Warranty Structure: Read the Fine Print
Every siding manufacturer's warranty is written to protect the manufacturer first. That's normal and not a criticism specific to LP. But it's worth understanding what a warranty actually covers versus what it sounds like it covers.
| Factor | Engineered Wood (LP SmartSide) | Fiber Cement (James Hardie) |
|---|---|---|
| Base material behavior | Wood-based; can swell or degrade if moisture penetrates coating | Cement-based; not susceptible to rot or organic decay |
| Field-cut sealing requirement | Mandatory on every cut, or warranty coverage can be affected | Recommended for best performance, less warranty-critical |
| Coating/finish | Factory primer; typically field-painted after install | ColorPlus factory finish available, baked-on, doesn't require immediate field painting |
| Typical manufacturer warranty length | Commonly around 5 years full coverage, prorated longer | Non-prorated coverage commonly in the 30-year range on Hardie products |
| Transferability to new owner | Varies, often limited or shortened on transfer | Typically transferable, supporting resale value |
The warranty gap alone is a big part of why we made the switch. A shorter, prorated warranty on a wood-based product means the homeowner is carrying more of the long-term risk, especially in a wet climate where the material is already working harder than it would in a dry one.
What This Costs You in Practical Terms
We won't quote made-up numbers, but here's the honest framing: LP SmartSide typically costs less upfront than James Hardie fiber cement, both in material and sometimes in labor. If your budget is the primary driver and your home isn't especially exposed to weather, that upfront savings is real and shouldn't be dismissed.
What we ask homeowners to weigh against that is the maintenance and repaint cycle over the life of the siding, the repair cost if moisture does get behind a seam or cut edge, and the resale conversation when a future buyer's inspector flags engineered wood siding that's showing early wear in a wet-climate home. Over a 20 to 30 year ownership window in Seattle's weather, we've found the total cost picture tends to favor fiber cement — but that's a judgment call every homeowner should make with real information, not fear.
Why We Standardize on James Hardie Instead
We made a business decision to install only James Hardie fiber cement siding, across every job, rather than offering a menu of products. That's partly about consistency of quality — we know the material, the fastening schedule, and the flashing details cold, on every house — and partly about matching the product to King County's specific climate demands:
- Non-combustible material, which also matters for fire-rated assemblies and insurance considerations
- Not susceptible to rot, since there's no organic wood content to break down
- HZ5 and climate-engineered product lines built specifically for wet, moisture-heavy regions like ours
- ColorPlus factory finish that holds up under UV and moisture without an early repaint cycle
- A stronger, non-prorated warranty structure that transfers to a future owner
We're not claiming Hardie is the right siding for every climate in the country. We're saying that for Seattle's driving rain, salt air, and moss season, it's the product we're willing to put our name behind — and the one we'd choose for our own home.
Questions to Ask Before You Choose a Siding Product
Whether you go with us or another contractor, here's a practical checklist worth working through before you commit to any siding material:
- What is the manufacturer's actual warranty length, and is it prorated or full coverage?
- Does the warranty transfer to a future homeowner, and under what conditions?
- What sealing or treatment is required at every field cut, and is the installer doing it on every single cut?
- How does this product perform specifically in wet, coastal, or moss-prone conditions — not just in general marketing claims?
- What's the expected repaint or recoat cycle, and what does that cost over 15-20 years?
- Is the installer certified or specifically trained on this exact product's installation requirements?
If a contractor can't answer these clearly and specifically, that's worth noting before you sign anything.
Let's Talk About Your Home
Every house on the Sound is a little different — sun exposure, tree cover, wall orientation, and moss pressure all vary block to block, sometimes house to house. If you're weighing siding options for a Seattle or King County home, we're glad to walk your property, look at your specific exposure, and give you a straightforward assessment of what we'd recommend and why. There's no pressure and no obligation — just a free estimate and an honest conversation.