This fiber cement lap siding delivers contractor-grade durability with a 50-year substrate warranty and machine-applied PPG coating. At 2.3 lbs per square foot, it’s engineered for Montana’s extreme weather while meeting strict fire safety requirements in wildfire-prone regions.
Technical Specifications and Fire Ratings
The numbers tell the story. Each board runs 12 feet long by 8-1/4 inches wide at 5/16 inch thickness. Standard installation uses a 7-inch exposure with 1-1/4 inch overlap. That weight — approximately 2.3 lbs per square foot — means structural load calculations matter, especially on older homes.
Fire performance exceeds Montana’s WUI requirements. NFPA Class A Fire Rating with a Flame Spread Index of 0 and Smoke Developed Index less than 5. Non-combustible classification matters when building in the interface zones around Kalispell or Stevensville.
| Specification | Value | Source |
|---|---|---|
| Length | 12 feet (3,658 mm) | Manufacturer |
| Width | 8-1/4 inches (210 mm) | Manufacturer |
| Thickness | 5/16 inch (7.9 mm) | Manufacturer |
| Weight | Approximately 2.3 lbs/sq ft | Manufacturer |
| Fire Rating | NFPA Class A | Tested |
| Flame Spread | 0 | ASTM E84 |
| Smoke Developed | < 5 | ASTM E84 |
Warranty Coverage and Installation Requirements
The 50-year transferable, non-prorated substrate warranty covers the fiber cement board itself. Northwest Factory Finishes backs the ArmorShell/PPG coating with a separate 15-year transferable limited finish warranty. Coverage includes peeling, flaking, and excessive chalking — subject to proper installation.
Installation demands precision. Use a circular saw with carbide-tipped blade for cutting — standard blades won’t handle fiber cement. Fasteners must be corrosion-resistant hot-dipped galvanized or stainless steel 6d or 8d siding nails. Skip the electro-galvanized nails. They’ll rust.
Leave a 1/8 inch gap at all trim locations for sealant. That gap allows for thermal movement. Maintain 1-1/4 inch minimum overlap for lap siding. Storage requirements: covered, off the ground, on a flat surface — keep dry until installation.
The proprietary ArmorShell color-finishing process uses machine-applied PPG coating. Factory application beats field painting for consistency and adhesion. The board features realistic wood grain texture (Traditional Cedar) that holds up better than smooth finishes in freeze-thaw cycles.
Montana Building Applications
FEMA Class 5 flood-damage-resistant material rating addresses another Montana concern — spring flooding in river valleys. Termite and rot resistant properties matter less here than in warmer climates, but the rot resistance handles snowmelt moisture at the foundation line.
ICC-ES/QAI CERus-1012 Certification and ASTM C1186: Type A, Grade II compliance mean this product meets commercial building standards. Florida Building Code (FBC) and Miami-Dade NOA compliant — overkill for Montana, but shows the testing rigor.
Professional contractors expect 50 to 100 years from fiber cement siding when properly maintained. That longevity justifies the weight penalty and specialized cutting requirements. Improper installation can lead to paint peeling or moisture infiltration — follow the specs exactly.
Frequently Asked Questions
What tools do I need to cut fiber cement siding? A circular saw with carbide-tipped blade handles the cutting. Regular blades dull immediately. Some contractors prefer fiber cement shears for cleaner cuts with less dust.
Can I use regular nails for installation? No. Corrosion-resistant fasteners — either hot-dipped galvanized or stainless steel 6d or 8d siding nails — are mandatory. Electro-galvanized nails will rust and stain the siding.
How much gap should I leave at trim boards? Allow 1/8 inch gap at all trim locations for sealant. This gap accommodates thermal expansion and prevents buckling.
What’s included with each board purchase? Individual 12-ft siding boards. Accessories like touch-up paint, color-matched caulk, and trim are sold separately.
How does the warranty transfer to new homeowners? Both the 50-year substrate warranty and 15-year finish warranty are transferable. Documentation requirements vary — check warranty terms at installation.
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