LP SmartSide vs James Hardie: A Seattle Contractor’s Honest Comparison
We install both products regularly. Neither is universally better — each has real advantages depending on your home, budget, and priorities. Here’s the straight comparison from someone who works with both every week.
LP SmartSide vs James Hardie: Side-by-Side Comparison
Here’s the quick reference before we get into the details:
| Category | James Hardie (HZ10) | LP SmartSide |
|---|---|---|
| Material | Fiber cement (portland cement, sand, cellulose) | Engineered wood (OSB with SmartGuard treatment) |
| Installed Cost | $14 – $20/sq ft | $15 – $21/sq ft |
| Warranty | 30-year non-prorated | 50-year substrate (5/15 finish) |
| Moisture Resistance | Excellent (HZ10 formulation) | Very good (SmartGuard zinc borate) |
| Impact Resistance | Moderate (can crack on hard impact) | Excellent (absorbs impact without cracking) |
| Fire Rating | Non-combustible (Class A) | Combustible (Class C, treated) |
| Weight | Heavy (~2.5 lbs/sq ft) | Lighter (~1.5 lbs/sq ft) |
| Maintenance | Repaint every 12–15 years | Repaint every 10–12 years |
| Termite Resistance | Immune (no organic material) | Treated (zinc borate deters) |
Price Difference: LP SmartSide vs Hardie in Seattle
LP SmartSide is no longer the cheaper option. After LP’s material price increases, it runs $15–$21/sq ft installed in Seattle vs. $14–$20/sq ft for James Hardie — so on a typical Seattle-area home with 1,800 square feet of wall area, LP usually lands at or slightly above Hardie for the same scope of work.
What drives the price today:
- Material cost: LP SmartSide boards used to cost less per piece at the distributor level, but LP’s price increases have erased that edge.
- Faster installation: SmartSide is significantly lighter than Hardie (about 60% of the weight). Lighter boards mean faster handling, easier cutting, and less crew fatigue. That can trim labor time on larger projects, but not enough to make LP the cheaper option overall.
That said, the cheapest siding is the one that lasts. With installed prices this close, the choice should come down to performance — impact resistance, 16-foot boards, and a deeper wood grain for LP; fire and moisture resistance for Hardie — not price. Both are real, proven products when installed correctly.
How Each Handles Seattle’s Rain
This is the question every Seattle homeowner should ask first. Both products handle moisture well, but they approach it differently:
Fiber cement is inherently moisture-resistant because it’s essentially cement. HZ10 adds additional proprietary additives that reduce water absorption in high-moisture climates. Hardie boards don’t swell, warp, or rot in the traditional sense. Their vulnerability is at cut edges and where fasteners penetrate — which is why manufacturer-spec installation matters so much. More on our Hardie installation process.
SmartSide uses LP’s proprietary SmartGuard manufacturing process, which saturates the engineered wood substrate with zinc borate and bonds a resin-impregnated overlay to the surface. Zinc borate provides resistance to moisture, fungal decay, and termites throughout the board — not just on the surface. Cut edges need to be treated with LP’s recommended sealant, and back-priming all cuts is essential for long-term performance in the PNW. More on our LP SmartSide installation.
The honest take: Both hold up well in Seattle when installed by someone who follows the manufacturer specs. Hardie has a slight edge in raw moisture resistance because fiber cement simply cannot rot. LP SmartSide’s vulnerability is at cuts and penetrations if they’re not sealed properly. With proper installation, both give you decades of performance.
Warranty Comparison: What’s Actually Covered
Warranty numbers are marketing tools until you read the fine print. Here’s what each warranty actually means:
Hardie’s warranty covers the substrate for 30 years, non-prorated — meaning they cover repair or replacement cost in full for the entire 30 years, not a declining percentage. The ColorPlus factory finish carries a separate 15-year warranty. Requirements: the correct climate-zone product (HZ10 in Seattle) and installation per Hardie’s written instructions. As a James Hardie Certified Installer, we install every project to that spec.
LP’s substrate warranty is 50 years, which is the longest in the category. However, it’s prorated after year 5 — coverage decreases over time. The factory prefinish warranty is either 5 years (standard) or 15 years (ExpertFinish). Requirements: installation per LP tech bulletins, proper gapping, back-priming of cuts, and integration with WRB. Details on our LP installation standards.
The real-world takeaway: Hardie’s non-prorated warranty is more valuable in practice than LP’s longer but prorated one. But LP’s 50-year substrate coverage still signals strong confidence in the product’s longevity. Both warranties are void if the installation doesn’t meet manufacturer specs — which is why who installs your siding matters as much as what brand you choose.
When Each Product Makes Sense in Seattle
• Maximum moisture resistance is the top priority
• Fire resistance matters (wildland-urban interface, close lot lines)
• You want the strongest non-prorated warranty
• You plan to stay in the home long-term (30+ years)
• You prefer a subtler, more uniform wood-grain texture
• The home has complex details requiring precise custom cuts
• You want 16-foot boards with fewer seams on long walls
• Impact resistance is important (kids, hail, debris)
• You want a wood-grain texture that looks more natural
• The home is in a lower-exposure location (not directly coastal)
• Faster installation timeline is preferred
• You want the 50-year substrate confidence
Here’s what we tell homeowners: if maximum moisture and fire resistance come first, Hardie HZ10 is the safest choice for Seattle. If impact resistance, 16-foot lengths, or a deeper wood-grain look matter more to you, and you hire a contractor who follows LP’s installation details to the letter, SmartSide is a genuinely strong alternative at a similar installed price. What matters more than the product name is that the WRB, flashing, and installation details are done correctly.
We install both products regularly and stand behind both. Tell us about your project and we’ll help you figure out which one makes the most sense for your specific situation.
Aesthetics: How They Actually Look on a House
Appearance matters — it’s your house, and you’re going to look at it every day. Here’s the honest comparison:
- Hardie HardiePlank: Smooth or cedarmill (wood grain) textures. The cedarmill texture is subtle and consistent. HardiePlank has a distinctive look that’s become so popular in Seattle that many neighborhoods have a recognizable “Hardie look.” ColorPlus factory finish offers 30+ color options with excellent fade resistance.
- LP SmartSide: Deeper, more pronounced wood-grain texture that many homeowners feel looks more like real wood than Hardie’s cedarmill. Available in smooth and textured profiles. If you want a traditional, warm wood look without actual wood maintenance, SmartSide has the edge aesthetically. Factory prefinish is available in a range of colors.
Both products come in lap siding, vertical panels, trim, and soffit options. Profile dimensions are similar. In most cases, neighbors can’t tell the difference from the sidewalk — the color, trim details, and overall design matter more than the material for curb appeal.
You don’t always have to pick one, either. On a new craftsman we sided in Seattle, HardieShingle went in the gables and LP SmartSide lap on the walls — both primed, painted on site and hung on the same furring-strip rainscreen, so the change in texture reads as craftsman detailing rather than a material mismatch.
LP SmartSide vs James Hardie FAQ
Is LP SmartSide or James Hardie better for Seattle?
Both perform well when properly installed. Hardie HZ10 has a slight edge in raw moisture resistance since fiber cement cannot rot. LP SmartSide is lighter, has better impact resistance, and offers a deeper wood-grain texture. Hardie is our more common recommendation for maximum durability in the marine climate, but LP SmartSide is a strong choice when impact resistance or its deeper wood-grain look matters.
Is LP SmartSide cheaper than James Hardie?
Not anymore. LP SmartSide now typically runs $15 to $21 per square foot installed in Seattle, compared to $14 to $20 per square foot for James Hardie. LP has raised its material prices, so for the same scope of work (tear-off, WRB, flashing, and proper installation) LP now lands at or slightly above Hardie. Choose on performance instead: LP for impact resistance and 16-foot lengths with fewer seams, Hardie for fire resistance and maximum moisture resistance.
Does LP SmartSide hold up in Seattle rain?
Yes, when properly installed with WRB, flashing, and sealed cut edges. LP’s SmartGuard process treats the wood with zinc borate throughout the board. The key is that all cut ends must be back-primed and sealed, and the siding must be integrated with a proper weather-resistant barrier. Without these details, any siding will fail in Seattle.
Not Sure Which Material Is Right for Your Home?
Paul installs both James Hardie and LP SmartSide regularly. He’ll inspect your home, talk through the pros and cons for your specific situation, and give you honest pricing for both options. No pressure either way.
GP General Corp · LP SmartSide & James Hardie Installer · WA License #GPGENGC830KD