Lynden Door CD600: 60-Minute Fire-Rated Interior Doors

The CD600 delivers 60-minute fire rating (UL 10C positive pressure tested) for commercial interiors where code compliance matters. Georgia-Pacific mineral core construction provides proven fire resistance for schools, hospitals, and office corridors. At 1-3/4” (45 mm) thickness with Firestop II composite stiles, these doors handle the demands of high-traffic commercial spaces.

Interior fire-rated barriers, corridor fire compartments, and fire walls requiring a 60-minute rating — that’s where the CD600 belongs. Designed for interior use only; not recommended or warranted for exterior applications. Montana contractors working on schools, medical facilities, or multi-family projects need reliable fire-rated assemblies that meet code without drama.

Fire Performance and Testing Standards

The numbers tell the story. 60 minutes (Standard) fire resistance under UL 10C (Positive Pressure) testing — the toughest standard for fire doors. Positive pressure testing simulates real fire conditions where hot gases push against the door. Positive-Pressure Category A or Neutral-Pressure Category B ratings mean these doors work in demanding applications.

Specification	Value	Source
Fire Rating	60 minutes	MINERAL core confirmed
Test Standards	UL 10C (Positive Pressure), UL 10B (Neutral Pressure), NFPA 252, UBC 7-2 1997, UBC 7 1994	Manufacturer
Maximum Single Door Size	4’ 0” x 10’ 0”	Manufacturer
Maximum Size (Positive Pressure)	4’ x 9’	Manufacturer
Maximum Pair Size	Up to 8’ 0” x 9’ 0”	Manufacturer

The Georgia-Pacific mineral core (fire-rated material per WDMA/ASTM standards) isn’t just marketing speak. This core material passes the burn tests that matter for life safety. Firestop II construction adds another layer of protection through engineered stiles and rails that maintain integrity during fire exposure.

Core Construction and Materials

Type 1 waterproof adhesives hold everything together — critical when temperature differentials stress the assembly. No added urea-formaldehyde/NAUF options available for projects requiring cleaner indoor air quality.

Face options match project requirements:

• HPVA Architectural ‘A’ grade wood veneer (>= 1/50” (0.5 mm) before sanding)
• AA’ grade wood veneer (Optional)
• High Pressure Decorative Laminate (HPDL) - NEMA LD3/ISO 4586
• Medium Density Overlay (MDO) - Paint Grade
• High Density Fiberboard (HDF/PC-3)

Firestop II composite rails with outer softwood band or optional (CE) wood rails compatible with face veneer. The engineering shows in the details — composite cores for fire resistance, solid wood edges where hardware mounts.

Installation Requirements and Warranty

Storage matters. Temperature 50°F to 90°F; relative humidity 25% to 55% keeps doors stable before installation. Doors must be stored in a climate-controlled environment (50-90°F, 25-55% RH) — Montana contractors know what happens to unsealed wood products in temperature swings.

Critical requirement: Top and bottom rails must be sealed with paint or varnish within 5 days of arriving at the job site. Miss this deadline and warranty coverage disappears. Stack horizontally on 1.5” (38 mm) blocking; protect with cover sheets; ensure air circulation during storage.

Hardware requirements:

• Minimum 3 hinges for doors up to 7’ tall
• Add one hinge for each additional 12” of height
• Fire-rated glass cut-outs must be factory-prepared and meet label service requirements (typically <= 100 sq. in. per leaf)

5-year limited warranty for interior use covers defects when installed within 1 year of sale. Excludes exterior use, field finishes, and damage from improper handling/storage.

The CD600 earns its place in commercial projects through proven fire performance and straightforward installation requirements. Montana contractors dealing with schools and hospitals understand the value of doors that meet code without callbacks. Compatible with standard commercial hardware; reinforcement blocking (WDMA HB-1 through HB-8) can be specified for exit devices and closers.

90-minute fire rating needs jump to the CD900 model with similar construction. For most corridor and fire wall applications, the CD600’s 60-minute rating handles code requirements efficiently.

Frequently Asked Questions

Q: What’s the actual fire rating on the Lynden Door CD600?

The CD600 provides a 60-minute fire rating tested to UL 10C positive pressure standards, which simulates real fire conditions. The door meets Positive-Pressure Category A or Neutral-Pressure Category B requirements, with maximum single door size of 4’ x 9’ for positive pressure applications.

Q: Can I use the CD600 for exterior doors?

No, the CD600 is designed for interior use only and is not recommended or warranted for exterior applications. The 5-year limited warranty specifically excludes exterior use, and the door construction is engineered for interior fire-rated barriers, corridor fire compartments, and interior fire walls.

Q: What face materials are available on the CD600?

Lynden Door offers the CD600 with HPVA Architectural ‘A’ grade wood veneer (minimum 1/50” thick before sanding), High Pressure Decorative Laminate (HPDL), Medium Density Overlay (MDO) for paint-grade applications, or High Density Fiberboard (HDF/PC-3). The HPDL version comes as a 5-ply construction meeting NEMA LD3/ISO 4586 standards.

Q: How soon do I need to seal the CD600 after delivery?

Top and bottom rails must be sealed with paint or varnish within 5 days of arriving at the job site to maintain warranty coverage. Doors must be stored in a climate-controlled environment between 50-90°F with 25-55% relative humidity, stacked horizontally on 1.5” blocking with proper air circulation.

Q: What’s the difference between the CD600 and CD900?

The CD600 provides a 60-minute fire rating while the CD900 delivers 90-minute fire protection, both using similar Georgia-Pacific mineral core and Firestop II construction. For most corridor and fire wall applications, the CD600’s 60-minute rating meets code requirements, but projects requiring extended fire resistance need the CD900.

Q: What hardware requirements should I plan for with the CD600?

The CD600 requires minimum 3 hinges for doors up to 7’ tall, adding one hinge for each additional 12” of height. The door is compatible with standard commercial hardware and can be specified with reinforcement blocking (WDMA HB-1 through HB-8) for exit devices and closers.