Why Fire Ratings Matter
When an access panel is installed in a fire-rated wall or ceiling assembly, the panel itself must carry a matching or greater fire rating. Installing a non-rated or under-rated panel in a fire-rated assembly creates a code violation and—more importantly—a genuine life-safety risk. Building inspectors will flag it, and insurance claims can be denied if a fire spreads through an improperly rated opening.
How Fire Ratings Are Measured
Fire ratings are expressed in minutes and represent how long a door or panel assembly can withstand a standardized fire test (ASTM E119 / UL 263 for walls and floors; UL 10B/10C for door assemblies). The rating tells you how long the assembly maintains its integrity—preventing flames and hot gases from passing through—under controlled test conditions.
The Four Common FR Ratings
150FR – 1.5-Hour Fire Rating
A 150FR panel is rated for 1.5 hours (90 minutes). This is the most common rating for access doors installed in 1-hour and 1.5-hour rated wall and ceiling assemblies, which are typical in commercial corridors, tenant separation walls, and light commercial construction.
Use 150FR when: your wall or ceiling assembly is rated at 1 hour or 1.5 hours.
Shop KRP-150FR Fire Rated Access Doors
250FR – 2.5-Hour Fire Rating
A 250FR panel is rated for 2.5 hours (150 minutes). These are used in 2-hour rated assemblies found in occupancy separation walls, stairwell enclosures, and exit corridors in mid-rise commercial buildings.
Use 250FR when: your assembly is rated at 2 hours and local code requires a panel rated to exceed the assembly rating.
Shop KRP-250FR Fire Rated Access Doors
350FR – 3.5-Hour Fire Rating
A 350FR panel is rated for 3.5 hours (210 minutes). This rating is required in 3-hour rated assemblies, which appear in high-occupancy buildings, fire walls between structures, and certain industrial applications.
Use 350FR when: your project involves 3-hour fire walls or high-occupancy separation assemblies.
Shop KRP-350FR Fire Rated Access Doors
450FR – 4.5-Hour Fire Rating
A 450FR panel is rated for 4.5 hours (270 minutes). This is the highest commonly available rating, used in 4-hour fire walls that separate buildings or high-hazard occupancies. These are typically required by code in large industrial facilities, warehouses, and building-to-building separation walls.
Use 450FR when: your assembly is a 4-hour fire wall or the authority having jurisdiction (AHJ) requires the highest available rating.
Shop KRP-450FR Fire Rated Access Doors
Quick Reference: FR Rating Chart
| Rating | Duration | Typical Assembly | Common Applications |
|---|---|---|---|
| 150FR | 90 min | 1–1.5 hour walls/ceilings | Corridors, tenant separation, light commercial |
| 250FR | 150 min | 2-hour walls | Stairwells, exit corridors, occupancy separation |
| 350FR | 210 min | 3-hour walls | High-occupancy buildings, fire walls |
| 450FR | 270 min | 4-hour walls | Industrial, warehouse, building separation |
How to Confirm the Right Rating for Your Project
- Check the architectural drawings – The wall or ceiling assembly rating is specified on the plans, typically in the partition schedule or general notes.
- Consult the AHJ – The Authority Having Jurisdiction (local building department or fire marshal) has final say on required ratings.
- Match or exceed the assembly rating – The access door rating must meet or exceed the rating of the assembly it penetrates. Never install a lower-rated panel in a higher-rated assembly.
- Look for the label – Compliant fire-rated panels carry a permanent UL or WH label affixed to the door. Inspectors will look for this.
Shop All Fire-Rated Access Panels
Browse our full fire-rated collection, including both Karp and Elmdor options for walls and drywall surfaces:
