Lynden Door CD350 Commercial Interior Door

The CD350 is a high-performance commercial interior flush door featuring a Structural Composite Lumber (SCL) core, designed for nonresidential applications requiring superior strength, sound attenuation, and durability. For Montana contractors dealing with extreme temperature differentials and moisture challenges, the CD350’s SCL core provides higher strength and moisture resistance than particleboard — a critical advantage when interior doors face 70°F temperature deltas between heated spaces and unheated areas.

Core Performance That Actually Matters

The SCL core changes everything about how this door performs under stress. No additional blocking required for most hardware (complies with WDMA TM-10 extra heavy duty screw-holding) — that’s real labor savings on commercial jobs. Standard particleboard cores require blocking for heavy hardware. The CD350 doesn’t.

The CD350 uses an SCL core, providing higher strength and a superior STC 35 rating compared to the particleboard/agfiber cores of the CD200/250 (which typically offer STC 31). Four STC points might not sound like much, but it’s the difference between hearing conversations through the door and maintaining actual privacy in conference rooms.

Specification	CD350 Value	Source
Core Type	Structural Composite Lumber (SCL) WDMA IS 1-A C-3	Manufacturer
Acoustical Rating	STC 35 (ASTM E90-09) with OITC 31	Tested
Face Options	HPVA Architectural ‘A’ grade wood veneer (min. 1/50” / 0.5mm)	Manufacturer
Thickness Options	1-3/8” (35mm), 1-3/4” (45mm)	Manufacturer
Maximum Size	4’0” x 9’0” (1219mm x 2743mm) positive pressure	Manufacturer
Fire Rating Options	20-Minute (Positive Pressure Category B or Neutral Pressure)	Manufacturer
Adhesive Type	Type 1 (non-urea-formaldehyde / NAUF)	Manufacturer

Sound Control and Environmental Compliance

SCL core doors like the CD350 are considered ‘Extra Heavy Duty’ compared to standard ‘Heavy Duty’ hollow-core or basic particleboard doors. That extra density delivers measurable acoustic performance. Healthcare facilities, law offices, and corporate conference rooms need doors that block sound. The CD350’s integrated design delivers.

Environmental friendliness: TSCA Title VI compliant and NAUF (No Added Urea-Formaldehyde) — not just marketing fluff. Montana’s growing healthcare sector requires TSCA compliance for indoor air quality. FSC®-Certified options available (License FSC-C103189) for projects chasing LEED points.

The integrated rail design matters. Rails: Integrated as part of the core (Structural Composite Lumber) creates uniform density across the door. No weak spots at rail joints where sound leaks through. Higher fire-rating models (45-90 min) use mineral cores, which are lighter but offer lower STC ratings (~30) compared to the CD350’s STC 35. Pick your priority — maximum fire rating or superior acoustics. The CD350 balances both.

Installation Reality

Factory machining is recommended for hardware cutouts using manufacturer templates — translation: don’t try to field-modify these doors. The SCL core machines differently than particleboard. Wrong bits or speeds will tear out the face veneer.

Storage matters more than contractors think. Storage must be flat, dry, and in a well-ventilated environment with a vapor barrier and Relative humidity must be maintained between 25% and 55%. Montana jobsites rarely maintain those conditions. Plan accordingly — climate-controlled storage or immediate installation.

Five (5) years interior limited warranty beats the typical one-year door warranty, but read the fine print. For interior use only; warranty is void if exposed to exterior elements and Installation space must be enclosed and watertight with HVAC systems operational. No storing these in unheated warehouses through a Montana winter.

The CD350 fills a specific niche — commercial projects that need genuine acoustic performance without custom pricing. The SCL core delivers strength where particleboard fails. The integrated rail design simplifies hardware installation. For healthcare facilities, corporate offices, and institutional buildings where privacy and durability matter equally, the CD350 earns its specification.

Frequently Asked Questions

Q: What’s the actual sound rating on the Lynden Door CD350?

The CD350 delivers an STC 35 rating (ASTM E90-09) with OITC 31, which is 4 points higher than standard particleboard core doors like the CD200/250 series that typically offer STC 31. That’s enough difference to block normal conversation through the door in commercial applications.

Q: Is a fire-rated version of the CD350 available?

Yes, Lynden Door offers the CD350 with optional 20-minute fire ratings in either Positive Pressure Category B or Neutral Pressure configurations. The standard CD350 comes non-rated, so you’ll need to specify fire rating when ordering.

Q: What size limitations apply to the CD350?

The CD350 maxes out at 4’0” x 9’0” (1219mm x 2743mm) for positive pressure applications, or 3’0” x 10’0” (914mm x 3048mm) for neutral pressure installations. Standard thickness options are 1-3/8” (35mm) or 1-3/4” (45mm), with optional thickness up to 2-1/2” (57mm).

Q: Is blocking needed for hardware on the CD350’s SCL core?

No, the CD350’s Structural Composite Lumber core meets WDMA TM-10 extra heavy duty screw-holding requirements without additional blocking for most hardware. The integrated rail design and SCL density eliminate the blocking requirement that particleboard cores need.

Q: What face veneer options come on the CD350?

Standard faces are HPVA Architectural ‘A’ grade wood veneer (minimum 1/50” / 0.5mm), with options for ‘AA’ grade wood veneer, paint grade MDO, HDF (PC-3), or High Pressure Decorative Laminate (HPDL). All veneers use Type 1 NAUF (no added urea-formaldehyde) adhesives.

Q: What’s the warranty on Lynden Door CD350 doors?

Lynden Door provides a 5-year limited warranty on the CD350 for interior use only, requiring the door remain in climate-controlled conditions (25-55% relative humidity, 50-90°F) with HVAC operational. Exposure to exterior elements voids the warranty completely.