Lynden Door Routed Primed Hardboard Doors

Lynden Door’s routed primed hardboard doors combine engineered wood construction with factory-primed surfaces, delivering code-compliant interior doors that contractors can customize on-site. The routed profile elevates these beyond basic flush doors while the primed hardboard surface eliminates field priming. Available in both hollow-core (H8, H4) and solid-particleboard core (P8, P4, P20) configurations, these doors adapt to everything from budget apartments to sound-rated commercial offices.

Fire Ratings and Core Performance

The P20 particle-board core delivers 20-minute fire ratings as standard. For single swing doors up to 3’0” x 7’0”, 45-minute ratings are available. That flexibility matters when juggling code requirements across mixed-use projects.

Core selection drives performance beyond fire ratings. Hollow-core options (H8, H4) keep weight down for high-traffic applications where doors see constant use. Solid-particleboard cores (P8, P4, P20) deliver superior sound control and impact resistance — critical for medical offices, schools, or any space where privacy and durability matter. STC ratings are available on request, though specific values aren’t published in standard literature.

Core Type	Fire Rating	Best Application
H8, H4 (Hollow)	Non-rated	Closets, light residential
P8, P4 (Solid)	Non-rated	Sound control applications
P20 (Solid)	20-minute	Code-required fire separation

The particleboard cores handle Montana’s temperature swings better than solid wood. No warping when the building goes from -20°F overnight to 70°F during the day.

Factory Preparation Saves Field Time

Wide top and bottom rails allow trimming up to 1 inch each end to accommodate rough openings. That’s double what most manufacturers allow. When framing isn’t perfect — and it rarely is — that extra trimming capacity prevents callbacks.

Factory machining for standard hardware (hinges, locks, latches) is available. Order doors pre-bored and you’re hanging them straight off the truck. The primed surface arrives ready for light sanding and priming of edges before final paint application. No field priming of faces. Just scuff, prime the edges, and shoot your finish coat.

The primed hardboard skins measure 12mm (0.5 inch) thickness, providing enough meat for aggressive sanding if needed. Pre-graded and acclimated prior to fabrication ensures dimensional stability — these doors won’t surprise you six months after installation.

Environmental Certifications Matter

CARB Phase II compliance and TSCA Title VI certification confirm low-formaldehyde construction. Indoor Advantage Gold certification validates indoor air quality performance. FSC certification is available upon request for projects chasing LEED points.

Environmental Product Declarations (EPD) are available, providing transparency for sustainability-focused projects. In a market where “green” claims run wild, Lynden backs their environmental story with third-party verification.

Sizing and Warranty Coverage

Standard heights include 6’8”, 7’0”, and 8’0”. Widths run up to 4’0” for passage and bifold doors. Both 1-3/8” (31mm) and 1-3/4” (44mm) thicknesses are available, with the thicker option providing better sound attenuation and a more substantial feel.

Warranty coverage varies by series: Standard Construction Series gets 1 year, Interior Commercial (IC) Series gets 5 years, and Architectural (LD) Series gets lifetime coverage when specified. The warranty structure reflects intended use — specify the right series for your project’s demands.

Real-World Applications

These doors work across residential interior applications (bedrooms, bathrooms, closets, entryways), light-commercial spaces (offices, small retail, apartments), educational and healthcare facilities, and both new construction and renovation projects.

The routed profile adds visual interest without the cost jump to raised panel doors. Compatible with standard interior door hardware, bifold systems, and vision lite cutouts, they integrate into any standard door package.

For Montana contractors dealing with mixed-use projects in Billings or Missoula, the combination of fire ratings and trimming allowances solves common field problems. Order them factory-machined and you’re looking at clean, efficient installations that pass inspection the first time.

FAQ

What’s the actual difference between hollow-core and solid-core options?

Hollow-core (H8, H4) doors use engineered wood construction for lighter weight, making them easier to handle and reducing wear on hinges in high-traffic areas. Solid-particleboard cores (P8, P4, P20) provide superior sound control and impact resistance. The solid cores also feel more substantial — less “hollow” sound when knocked.

Can these doors be trimmed more than the stated 1 inch?

The wide rails allow trimming up to 1 inch each end. Exceeding that risks exposing the core and voiding the warranty. For openings requiring more adjustment, order custom sizes rather than over-trimming standard doors.

Do the doors come with hardware?

Doors are delivered as routed, primed hardboard panels — hardware and hinges must be sourced separately. Factory machining for standard hardware preparations is available as an upcharge option.

What finish is required over the primer?

The factory primer requires light sanding and edge priming before final paint application. Any quality interior paint works — the primed surface accepts both latex and oil-based finishes equally well.

Are these suitable for fire-rated assemblies?

The P20 particle-board core provides 20-minute fire ratings. 45-minute ratings are available for single swing doors up to 3’0” x 7’0”. Always verify specific project requirements with local code officials — fire ratings depend on the complete assembly, not just the door.