Lynden Door 45-Min Rated Agfiber (Standard Construction)

The 45-minute fire-rated door uniquely combines agricultural fiber core technology with Category A compliance that eliminates edge-sealing requirements, saving installation time while meeting sustainability goals. This commercial-grade interior door delivers STC 31 acoustic rating and 45-minute fire protection at approximately 5.5 lbs/sq ft — lighter than many alternatives. For contractors working on garage-to-house entries or commercial partition walls, the agfiber core offers genuine environmental benefits without compromising fire performance.

Agfiber Core Technology & Performance

The core consists of agfiber particleboard composed of rapidly renewable, annually harvested agricultural fiber. This isn’t greenwashing. The core is made from annually harvested agricultural fiber with no added urea-formaldehyde (NAUF) options available. Both CARB Phase II and TSCA Title VI compliant, the door qualifies for LEED eligibility (MR Credit for rapidly renewable materials).

Performance specs tell the real story:

Specification	Value	Certification
Fire Rating	45-minute (Positive Pressure Category A/B or Neutral Pressure)	Warnock Hersey (Intertek)
Acoustic Rating	STC 31	Non-operable testing
Core Density	ANSI A208.1 LD1 or LD2	Manufacturer
Maximum Size	4’0” x 8’0” single-swing	Manufacturer
Thickness	1-3/4” standard (up to 2” available)	Manufacturer

The agfiber core offers similar fire protection and structural integrity to standard wood particleboard while utilizing rapidly renewable materials. It also provides a slightly higher acoustic rating (STC 31) compared to standard non-rated ag-fiber doors.

Installation Efficiency

Category A default classification means no additional edge-sealing system required for most configurations. That’s hours saved on every install. The door works with any Category C Standard Frame or listed Proprietary Frames, giving contractors flexibility with existing frame inventory.

Critical installation requirements:

• Must be installed as a single-swing door (pairs not allowed in standard 45-min Agfiber listing)
• Positive latching required with minimum 1/2” bolt throw
• WDMA blocking options (HB-1 through HB-8) available for surface-mounted hardware
• Door and frame must be in a dry, HVAC-controlled environment (RH 25-55%) prior to installation

Frame specifications keep it simple. Stiles run minimum 11/16” solid lumber or GP Firestop material (density min 27 pcf) with top rail minimum 5/8” and bottom rail minimum 3/4”. The faces come in 1/8” plywood, hardboard, MDO, or decorative plastic laminate.

Hardware & System Compatibility

The door accepts standard commercial hardware without special modifications. Compatible hardware includes cylindrical latches/deadbolts, mortise hardware, surface-applied closers, and exit devices (rim/mortise). With minimum 11/16” stile width, there’s adequate material for secure hardware mounting.

For smoke control applications, the door can bear ‘S’ label if used with listed Category H Smoke & Draft Control Gasket. This dual capability — fire and smoke — makes it practical for corridor and stairwell applications where both ratings matter.

The warranty varies by series: ‘Standard Construction’ doors typically carry a 1-year interior limited warranty, while ‘Architectural Series’ configurations may offer a ‘Life of original installation’ warranty for interior use.

What Makes It Work for Montana

At 45 minutes, this door meets Montana building code requirements for garage-to-house entries — a common application in residential construction. The agricultural fiber core aligns with Montana’s agricultural economy while delivering measurable performance benefits. No edge-sealing saves labor costs on commercial projects where dozens of doors need installation.

The door suits commercial interior applications like office partitions, schools, and hospitals, as well as residential fire-rated entryways. For contractors who understand that sustainable materials don’t have to mean compromised performance, this agfiber door delivers both.

FAQ

Does the agfiber core affect the door’s fire rating compared to traditional cores?

No. The agfiber core offers similar fire protection and structural integrity to standard wood particleboard while maintaining the full 45-minute rating with positive or neutral pressure testing options.

What’s the real installation advantage of Category A rating?

Category A default classification eliminates the need for additional edge-sealing systems. That means no special tapes, no intumescent strips, no extra labor — just hang it like a standard door while still meeting fire code.

Can these doors work in paired configurations?

Standard 45-minute agfiber doors must be installed as single-swing only — pairs are not allowed unless specifically modified. Maximum single door size is 4’0” x 8’0”.

What environmental certifications does the agfiber core carry?

The door offers no added urea-formaldehyde (NAUF) options and meets both CARB Phase II and TSCA Title VI compliance. It qualifies for LEED MR Credit for rapidly renewable materials.

How does the acoustic performance compare to other fire-rated doors?

The agfiber door provides a slightly higher acoustic rating (STC 31) compared to standard non-rated ag-fiber doors. While not the highest STC available, it’s respectable for a 45-minute rated door at this weight.